Planning of water quality monitoring systems

Planning of water quality monitoring systems
Technical
Report Series
No. 3
WMO-No. 1113
planning of water
quality monitoring systems
Technical
Report Series
No. 3
WMO-No. 1113
PLANNING OF WATER-QUALITY
MONITORING SYSTEMS
WMO-No. 1113
© World Meteorological Organization, 2013
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Contents
Page
Foreword.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Scope and objective. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Chapter 1. Processes affecting water quality and their effects .. . . . . . . . . . . . . . . . . . . 1.1 Effects of natural phenomena on water quality. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 Anthropogenic pressures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 Point loading and non-point loading. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 Spatial and temporal variations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 Variability of water quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1
2
4
5
7
Chapter 2. The importance of water-quality monitoring . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 Main purposes of a WQM programme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Monitoring for management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Hydrological monitoring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4 Types of WQM programmes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5 Early warning systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
8
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11
11
11
Chapter 3. Key elements of a water-quality monitoring programme . . . . . . . . . . . . . . . 13
Chapter 4. Strategies for meeting information needs of water-quality assessment.. . 4.1. Establishment of objectives of the monitoring programme. . . . . . . . . . . . . . . . . . 4.2. Water-quality monitoring information needs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Legislation and administrative setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
16
17
19
Chapter 5. Design of a monitoring programme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 Planning a monitoring network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Selection of sampling stations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3 Preliminary surveys. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4 Documentation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
20
21
22
23
Chapter 6. Selection of water-quality variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Classification of WQ variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Selection of variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.3 Hydrological variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
24
25
28
Chapter 7. Selection of water-quality monitoring methods and techniques. . . . . . . . . 7.1 Methods for field monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Frequency of sampling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3 Time of sampling. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
30
34
35
Chapter 8. Resources for a monitoring programme. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 Laboratory facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2 Inventory of field stations, monitoring wells, equipment and instruments. . . . . . 8.3 Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4 Staffing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5 Human-resources development and training. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.6 Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7 Estimation of costs of the programme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
37
38
38
40
41
42
42
iv
Planning of water-quality monitoring systems
Page
Chapter 9. Quality-assurance procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1 Components of quality assurance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.2 Laboratory facilities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3 Equipment maintenance, calibration and quality-control of fieldwork . . . . . . . . . 9.4 Analytical quality-control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.5 Quality assurance of data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6 WQ standards and indices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
45
46
46
47
48
48
Chapter 10. Data management and product development. . . . . . . . . . . . . . . . . . . . . . . . 10.1 Data handling and management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2 Data analysis and dissemination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3 Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
51
52
54
Chapter 11. International water-quality directives and guidance material. . . . . . . . . . . 11.1 International frameworks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Global databases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Related guidance material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
55
56
57
Chapter 12. Summary and future needs in water-quality monitoring. . . . . . . . . . . . . . . 59
Tables
Table 1 Categories and principal characteristics of water-quality
monitoring operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
Table 2 GEMS/Water variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Table 3 DPSIR framework for water quality of surface- and groundwater ecosystems. 64
Table 4 Selection of variables for assessment of water quality in relation to
non-industrial water uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Table 5 Selection of variables for the assessment of water quality in relation to some
key industrial uses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
Table 6 Selection of variables for the assessment of water quality in relation to
non-industrial pollution sources. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Table 7 Selection of variables for the assessment of water quality in relation to
some common industrial sources of pollution . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Table 8 Recommended annual sampling frequencies for GEMS/Water stations. . . . . 73
Table 9 Examples of responsibilities of staff on a water-quality
monitoring programme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74
Table 10 Management documents needed (ISO/IEC 17025, 2005) to implement
the quality assurance programme (quality manual) . . . . . . . . . . . . . . . . . . . . . 75
Annexes
Annex 1. Description of the main water-quality variables . . . . . . . . . . . . . . . . . . . . . . . . 1. General variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Nutrients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Organic matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Major ions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5. Other inorganic variables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6. Metals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7. Organic contaminants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8. Biological variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9. Microbiological indicators. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10. Sedimentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
76
80
81
82
82
83
84
85
87
87
Annex 2. Description of main water-quality monitoring methods and techniques. . . . 1. WQ monitoring equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2. Optical monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3. Simple field-measured variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4. Other important parameters that can be measured in situ . . . . . . . . . . . . . . . . . . . . . 89
89
89
90
91
Contents
v
Page
5. Traditional water-sampling for laboratory chemical and biological analysis. . . . . . . 93
6. Special sampling procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
7. Biological assessment and fish tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
8. Kits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
9. Remote-sensing (satellite, airborne or ground-based). . . . . . . . . . . . . . . . . . . . . . . . . 98
10. Advanced instrumental analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
11. Sampling procedures for isotopes in hydrological investigations. . . . . . . . . . . . . . . . 101
Appendices
Appendix 1.Summary of water-quality guidelines and standards by international
organization or country . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
Appendix 2 Key features of each chemical and physicochemical quality element (QE)
for lakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
Appendix 3. Key features of each biological quality element (QE) for lakes . . . . . . . . . . 108
References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
Acronyms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
Figures
Figure 1. Structure of water-quality monitoring operations. . . . . . . . . . . . . . . . . . . . . . . . Boxes
Box 1
Box 2
Box 3
Box 4
Box 5
Box 6
Box 7
Box 8
Box 9
14
Characteristics of spatial and temporal variations in water-quality. . . . . . . . . . . 6
Examples of the relationships between uses or functions and issues
in a river basin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Typical monitoring objectives. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Categories of water-quality parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Methods for field monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
Selected environmental variables that can be monitored automatically. . . . . . . 33
Biological, chemical and in situ water-quality monitoring: advantages and. . . . shortcomings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Main water-quality programme cost components. . . . . . . . . . . . . . . . . . . . . . . . . 43
Priorities to meet future needs for water-quality monitoring and assessment. . 60
Foreword
One of the United Nations Millennium Development Goals is to improve access to safe
water, which is an engine for socio-economic growth. In this context, the importance of
water- resources information systems cannot be overestimated in the socio-economic
development process of nations and the world environment.
World Meteorological Organization (WMO) Bulletin 61(1) (2012) states that the timing and
spatial distribution of surface water quantity – and the variability in quality of that water –
define how we design and build the infrastructure necessary for our energy, agriculture,
mining, transportation and industrial sectors. Safe drinking-water sources and entire
ecosystems depend on continuous improvements of our understanding of, and efforts to
protect, our water resources. One of the main messages from the Fifth Global Environment
Outlook (GEO-5, 2012) of the United Nations Environment Programme (UNEP) is that
addressing the most challenging water-resources issues facing society can be solved
equitably and efficiently with an integrated management approach directed to the
sustainable use of water.
In order to achieve this, it is essential that effective water-monitoring programmes,
together with sound data and information management, are operational globally.
Unfortunately, in many places in the world, such systems are not in place.
This Technical Report: Planning of Water Quality Monitoring Systems, has been developed
by WMO jointly with UNEP GEMS/Water in an effort to provide basic know-how and the
materials needed to plan, establish and operate water-quality monitoring systems on
national levels but also with a view to improving access to water-quality data and
information in transboundary basins and globally.
It is largely intended for use by water-agency managers whose dominant technical
background is in hydrology, meteorology, engineering or water-resources management,
rather than water quality, but who are responsible for the effective monitoring of
developments and trends in the state of inland waters. There is an extensive literature on
the setting-up and operation of water-monitoring programmes, so this Technical Report
should be viewed as a primer or basic tool to be used in conjunction with other more
detailed handbooks and academic literature.
It is hoped that national water managers and planners, as well as the international water
community, will find this report a useful tool that will lead to improved water-quality
networks in conjunction with hydrometric stations that will enhance water-quality
monitoring systems and a better assessment of the variability of water resources in terms
of both quality and quantity.
Acknowledgements
The Technical Report has been prepared as a team effort, involving a number of experts
from various fields of water-quality monitoring and management. In particular, the
following experts are acknowledged for their dedicated work and professional
contributions at various stages of its development:
Mr Antti Herlevi, provided the first draft document while working in the Hydrology and
Water Resources Branch of the WMO Secretariat and Mr Richards Robarts, former Director
of the UNEP GEMS/Water programme, and Ms Sabrina Barker, formerly with UNEP GEMS/
Water, provided the first full reviews and edits.
Highest appreciation is extended to the members of the editorial group who reviewed and
edited the document:
Mr Oscar E. Natale
National Water Institute
Argentina
Mr R.M. Bhardwaj
Central Pollution Control Board
India
Mr Isaac Hodgson
Achimota School
Ghana
Ms Jorma Niemi
Finnish Environment Institute
Finland
Special thanks go to Mr Julius Wellens-Mensah, former president of the Commission for
Hydrology (CHy), for his technical support and coordination and his relentless
encouragement to have the Technical Report published in the realm of CHy for the benefit
of all experts who are confronted with the rational development of water-quality
monitoring systems.
Planning of Water-Quality Monitoring Systems
Technical Report No.3
WMO in collaboration with UNEP GEMS/Water
Scope and objective
This publication discusses the monitoring of the quality of inland waters, including rivers
and streams of all sizes, from their source to tidal limit (i.e. the influence of saltwater
intrusion), canals and interconnecting river systems, lakes of all types and sizes, including
marshes and swamps, reservoirs and river impoundments and groundwater. These water
bodies comprise inland water resources which may be subject to anthropogenic influences
or are intentionally used for municipal or industrial supply, irrigation, recreation, cooling or
other purposes.
The target audience for this Technical Report comprises mainly managers of agencies
whose primary domain may not be water quality (WQ) but rather hydrology, meteorology,
engineering or water-resources management, and who have been tasked with undertaking
monitoring to support their main functions.
Many countries have a national WQ authority but also other agencies, whose primary
mandate has acquired an environmental dimension. The responsibility for WQ monitoring
and assessment is thus fragmented between different government departments, since the
information requirements and demands vary.
This Technical Report is intended to guide non-WQ officers through the process of setting
up monitoring programmes for the purpose of providing a valid database for water-quality
assessments, including general guidance to identify the purpose of the system, its
structure, choice of technology, institutional affiliation and expected results. The main
emphasis is on the strategies and objectives of the programme and general criteria for the
design of the monitoring network. Also described are the kinds of variables needed when
WQ is to be monitored for different purposes (such as agriculture/irrigation, drinking-water
sources, industrial water demand, livestock needs, etc.). Guidance on the selection of main
monitoring methods and techniques for the different variables is then provided. This is
followed by the definition of the resources required for the monitoring programme
(laboratory facilities, field stations, equipment and instruments, office and field staff and
the estimation of costs of the programme). Finally, the essential operational issues of
quality assurance and data handling, leading to the reporting and dissemination of results
and findings, are also covered.
The main thrust is on the setting-up or strengthening of WQ monitoring programmes for
the purposes of human consumption, agriculture/irrigation and industrial uses, etc.
Environmental WQ monitoring (e.g. biological systems, wetlands, etc.), although
mentioned, goes beyond the scope of this report and is therefore not described in detail.
A wealth of documentation is available on the subject of WQ monitoring and assessment,
some of which has been drawn heavily upon in this report, there being two major sources
of text: Bartram (1996)1 and several GEMS/Water publications2. Their use in conjunction
with the present Technical Report is therefore strongly recommended.
1
Bartram, J. and R. Ballance [Eds], 1996: Water Quality Monitoring: A Practical Guide to the Design and
Implementation of Fresh Water Quality Studies and Monitoring Programmes. Chapman & Hall, London.
2
These are available online at http://www.who.int/water_sanitation_health/resourcesquality/
waterqualmonitor.pdf and http://www.gemswater.org.
Planning of Water-Quality Monitoring Systems
ix
The structure of this treatise is illustrated in Chapter 3, Figure 1. It includes an indication of
the chapters where the relevant activities under each of the components of a WQ
monitoring programme are described. In addition, Chapter 11 contains a summarized
description of international WQ directives and relevant guidance material in related fields
that may be consulted as required for the various planning steps.
With a view to complementing the information and as technical support, Annexes 1 and 2
provide a detailed description of, respectively: (a) the main WQ variables; and (b) the
various WQ monitoring methods and techniques and monitoring equipment, as well as
traditional and special sampling procedures, etc. A summary of WQ guidelines and
standards by international organizations or countries is given in Appendix 1 and the key
features of each chemical and physicochemical element and each biological element for
lakes are given in Appendixes 2 and 3, respectively.
Planning of water-quality monitoring systems
Chapter 1. Processes affecting water-quality and their effects
Access to clean water for drinking and sanitary purposes is a precondition for human
health and well-being. Unpolluted water is also essential for ecosystems. Plants and
animals in lakes, rivers and seas react to changes in their environment caused by changes
in chemical water quality and physical disturbance of their habitat.
1.1 Effects of natural phenomena on water quality3
While the degradation of water quality (WQ) is almost invariably the result of human
activities, certain natural phenomena can result in WQ falling below the standard required
for particular purposes. Natural events such as torrential rainfall and hurricanes lead to
excessive erosion, landslides and mudflows, which, in turn, increase the content of
suspended material in affected rivers and lakes. Seasonal overturn of the water in some
lakes can bring water with little or no dissolved oxygen (DO) to the surface. These events
may be frequent or occasional and have increased as a result of climate change.
Permanent natural conditions in some areas may make water unfit for drinking or for
specific uses, such as irrigation.
Additionally, there are naturally occurring areas of high nutrients, trace metals, salts and
other constituents that can limit the use of water. Common examples are the salinization of
surface waters through evaporation in arid and semi-arid regions and the high salt content
of some aquifers under certain geological conditions. Many aquifers are naturally high in
carbonates (alkalinity), thus necessitating their treatment before use for certain industrial
applications. They may also contain specific ions (such as fluoride) and toxic elements
(such as arsenic IV, V) and selenium) in quantities that are harmful to health, while others
contain elements or compounds that cause other types of problems (such as the staining
of sanitary fixtures by iron and manganese).
The nature and concentration of chemical elements and compounds in a freshwater
system are subject to change by various types of natural processes – physical, chemical,
hydrological and biological – caused by climatic, geographical and geological conditions.
The major environmental factors are:
•
Distance from the ocean: extent of sea spray rich in Na+, Cl-, Mg2+, SO and other
ions;
•
Climate and vegetation: regulation of erosion and mineral weathering; concentration
of dissolved material through evaporation and evapotranspiration; increasing
turbidity and high silt load in rivers passing through hills of quaternary or recent
origin such as the Himalayan region;
•
Rock and sediment composition (lithology) and geological setting: these determine
the natural physical and chemical characteristics of the aquifers. The susceptibility of
rocks to weathering ranges from 1 for granite to 12 for limestone; it is much greater
for more highly soluble rocks (for example, 80 for rock salt);
•
Terrestrial vegetation: the production of terrestrial plants and the way in which plant
tissue is decomposed in soil affect the amount of organic carbon and nitrogenous
compounds found in water;
3
The content of this section is drawn verbatim from Bartram (1996), 23-25.
2
•
Planning of water-quality monitoring systems
Aquatic vegetation: growth, death and decomposition of aquatic plants and algae will
affect the concentration of nitrogenous and phosphorous nutrients, pH, carbonates,
DO and other chemicals sensitive to oxidation/reduction conditions. Aquatic
vegetation has a profound effect on the chemistry of lake water and a less
pronounced, but possibly significant, effect on river water;
Under the influence of these major environmental factors, the concentrations of many
chemicals in river water are liable to change from season to season. In small watersheds
(<100 km2) the influence of a single factor can cause a variation of several orders of
magnitude. WQ is generally more constant in watersheds greater than 100 000 km2, and
the variation is usually within one order of magnitude for most of the measured variables,
unless regulated. Regarding groundwater, changes in hydrodynamics and redox
(reduction-oxidation) conditions can change the interaction between the solid material and
the fluid resulting in change in the groundwater quality.
1.2 Anthropogenic pressures
Almost all human activities can and do have an adverse impact on water. WQ is
influenced by both non-point pollution from farming activities and point-source pollution
from sewage treatment and industrial discharge as principal sources. For agriculture, the
key pollutants are nutrients, pesticides, sediment and faecal microbes. Oxygenconsuming substances and hazardous chemicals are more associated with point-source
discharges.
According to the European Environment Agency (EEA): “the pollution can take many forms
and have different effects:
Faecal contamination from sewage makes water unsafe for human consumption and
aesthetically unpleasant and unsafe for recreational activities, such as swimming, boating
or fishing. Many organic pollutants, including sewage effluent, as well as farm and foodprocessing wastes, consume oxygen, suffocating fish and other aquatic life. Additionally,
this contamination can affect groundwater resources used for drinking-water purposes.
Nutrients, such as nitrates and phosphates, from farm fertilizers to household detergents,
can “overfertilize” the water, causing the growth of large mats of algae, some of which can
be toxic. When the algae die, they sink to the bottom, decompose, consume oxygen and
damage ecosystems. Additionally, due to the percolation of nutrients to shallow aquifers,
the chemical conditions in those aquifers can change.
Pesticides and veterinary medicines from farmland and some industrial chemicals can
threaten wildlife and human health. Some of these damage the hormonal systems of fish,
causing “feminization” (endocrine disruption).
Metals, such as zinc, lead, chromium, mercury and cadmium, are extremely toxic. Copper
complexes are less toxic, and cobalt and ferrous complexes are only weak toxicants.
Concentrations of cyanides in waters intended for human use, including complex forms,
are strictly limited because of their high toxicity.
Organic micropollutants, such as pharmaceuticals, hormones and chemical substances
used in products and households, can also threaten health.
Chlorinated hydrocarbons exist in the natural systems and several are highly toxic for
humans. These molecules persist in the environment for a longer time and threaten to
contaminate aquatic and soil systems.
Sediment runoff from the land can make water muddy, blocking sunlight and, as a result,
kill aquatic life. Irrigation, especially when used improperly, can bring flows of salts,
Chapter 1. Processes affecting water-quality and their effects
3
nutrients and other pollutants from soils into water. All these pollutants can also make the
water unsuitable for drinking purposes.”4
The physical management of rivers and aquifers and the wider hydrological and
hydrogeological environment of a river basin also influence ecological quality and WQ.
Changes and disruptions in natural habitats, such as bankside vegetation, can result from
the physical disturbance of damming; canalization and dredging of rivers; construction of
reservoirs; riverbank management and other changes to the hydrological flow; sand and
gravel extraction in coastal waters; bottom trawling by fishing vessels, etc. Pebble riffles
where salmon and other fish spawn can also be destroyed. Seasonal flow patterns that are
vital to many species can also be changed, as well as the connectivity between habitats –
an important factor for the functioning of aquatic ecosystems and the development of the
different life stages of aquatic organisms. In urban agglomerations, storm-water carrying
contamination from streets and roofs can contribute to water pollution if discharged
directly into water bodies.
Plants and aquatic life such as plankton and benthos in lakes, rivers and seas react to
changes in their environment caused by changes in chemical WQ and physical disturbance
of their habitat. Changes in species composition of organism groups such as
phytoplankton, algae, macrophytes, bottom-dwelling animals and fish can be caused by
changes in climate. They can also indicate changes in WQ caused by eutrophication,
organic pollution, hazardous substances or oil and a changing hydrological regime.
Over time, with the advent of industrialization and increasing populations, the range of
requirements for water has increased, together with greater demands for higher-quality
water, such as for drinking and personal hygiene, fisheries, agriculture (irrigation and
livestock supply), navigation for transport of goods, industrial production, cooling in fossil
fuel (and later also in nuclear) power plants, hydropower generation, heat/cold storage in
aquifers, recreational activities such as bathing or fishing and nature conservation,
e.g. wetlands. Fortunately, the largest demands for water quantity, such as for agricultural
irrigation and industrial cooling, require the least in terms of WQ (critical concentrations
may be set for only one or two variables, the most critical for the specific use of water,
such as salinity or nitrate contents for agricultural usage, etc.). Drinking-water supplies and
specialized industrial manufacturers exert the most sophisticated demands on WQ but
their quantitative needs are relatively moderate. In parallel with these uses, water has been
considered the most suitable medium to clean, disperse, transport and dispose of waste
(domestic and industrial waste, mine drainage waters, irrigation returns, etc.). It should be
noted that, in a natural water body, it would be better to consider the real pollutant load
and not only the pollutant concentration.
Each water use, including abstraction of water and discharge of waste, leads, however, to
specific and generally rather predictable impacts on the quality of the aquatic environment.
In addition to these intentional water uses, there are several human activities which have
indirect, undesirable – and sometimes devastating – effects on the aquatic environment.
Examples are uncontrolled land use for urbanization or deforestation and associated soil
erosion, accidental (or unauthorized) release of chemical substances and discharge of
untreated waste or leaching of noxious liquids from solid-waste deposits. Similarly, the
uncontrolled and excessive use of fertilizers and pesticides has long-term effects on
ground- and surface-water resources. Restoration of the natural WQ after such events
often takes many years, depending on the geographical scale and intensity of the event.
Pollution of groundwater arises commonly from the percolation of polluted water from the
surface, but also leaching from contaminated soil, dissolution from oil or dense
non-aqueous phase liquids. When polluted water penetrates to the point of abstraction, the
consequences are serious. Because of the slow rate of travel of the water in the aquifer and
the large volume of subterranean water, there is usually a considerable time-lag between
the casual activity and the appearance of the pollutant in the abstracted water. The rate of
4
EEA, State of Environment Report (SOE), 2005, 120-121.
4
Planning of water-quality monitoring systems
travel will depend upon pollutant persistence, hydraulic conductivity, hydraulic gradient
and porosity.
The continuing increase in socio-economic activities worldwide has been accompanied by
an even faster growth in pollution stress on the aquatic environment. Only after a
considerable time lapse, allowing for the public perception of WQ deterioration, have the
necessary remedial measures started to be taken.
1.3 Point loading and non-point loading
Discharges from wastewater-treatment plants and industry cause pollution by oxygenconsuming substances, nutrients and hazardous substances. The adverse impacts depend
very strongly upon the degree to which (if at all) such discharges are treated before
reaching waterways or whether such pollutants are degraded by the natural system itself.
By its very nature, the management of diffuse pollution is complex, requiring the careful
analysis and understanding of various natural and anthropogenic processes. The
estimation of non-point diffuse loading from the different processes to a water body is
not easy, because so many different factors affect quantity and spatial variations.
Modern-day agricultural practices often require high levels of fertilizers and manure,
leading to high-nutrient (e.g. nitrogen and phosphorus) surpluses that are transferred to
water bodies and groundwater through various non-point processes. Excessive nutrient
concentrations in water bodies, however, cause adverse effects by promoting
eutrophication, with an associated loss of plant and animal species. In high-nutrient
waters with sufficient sunlight, algal slimes can cover streambeds, plants can choke
channels and algae blooms can turn the water a murky green. Oxygen depletion, the
introduction of toxins or other compounds produced by aquatic plants, reduced water
clarity and fish kills can also result. Excess nutrient levels can also be detrimental to
human health.
Pesticides used in agriculture are transported to both surface water and aquifers. Not only
do they threaten wildlife and human health but excessive sediment runoff from
agricultural land results in turbid waters and the clogging of spawning areas. This, in turn,
leads to loss of aquatic habitats. Microbial pathogens from animal faeces can also pose a
significant health risk. High concentrations can restrict the recreational and water-supply
uses of water, cause illness and loss of productivity in cattle and limit shellfish
aquaculture in estuaries.
In urban areas, where surface runoff is not connected to treatment works, pollutants
deposited on impervious surfaces (e.g. roads or pavements) are washed into nearby
surface waters or percolate down to the shallow groundwater. Such pollutants include
metals, pesticides, hydrocarbons and solvents, as well as those derived from sources
such as the atmosphere and the abrasion of roads, tyres and brakes. In some urban areas,
surface runoff is discharged into sewers, which then mixes with sewage on its way to
treatment. During periods of heavy rainfall, the sewerage system is unable to cope with
the volume of water. As a result, the flow is directed away from the treatment works and
discharged as combined sewer overflow to surface water. This causes pollution from not
only sewer waste but also urban runoff.
Another important phenomenon is the so-called “internal loading” in dimictic lakes. In
many cases, it has been observed that, despite having totally stopped wastewater
discharge to a certain lake, the improvement of its ecological status has been extremely
slow. There are two main causes of internal loading:
•
Bottom sediments which, earlier, have deteriorated badly, owing to discharges of
insufficiently treated wastewater and which, during the purification process, transfer
Chapter 1. Processes affecting water-quality and their effects
5
extra nutrient reserves from the sediment to water, during an unusually long period;
and
•
Excessively dense fish stocks developed during the increasing eutrophication of
lakes, which usually comprise small roach, bream, etc. These are commonly
bottom-feeding and return sedimented nutrients, especially phosphorus, back to
the epilimnion in mineral form.
The atmosphere is the most pervasive means of transporting pollutants through the
global environment. Significant concentrations of certain contaminants (mercury and
persistent organic pollutants (POPs)) are even being observed in Arctic and Antarctic
snow and ice, with high levels of bioaccumulation magnified through the food chain to
mammals and native human populations. Sources of anthropogenic materials to the
atmosphere include:
•
Combustion of fossil fuels for energy generation;
•
Combustion of fossil fuels in automobiles, other forms of transport, heating in
cold climates and industrial needs (e.g. steel production);
•
Ore smelting, mainly sulphides, but also cadmium, zinc, lead, arsenic and copper;
•
Wind-blown soils from arid and agricultural regions; and
•
Volatilization from agriculture, waste disposal and previously polluted regions;
•
Emission of hydrogen sulphide (H 2S) and methane (CH 4 ) from municipal solidwaste disposable sites and sewage drains and open drains in developing
countries.
Together, these sources provide an array of inorganic and organic pollutants to the
atmosphere, which are then widely dispersed by weather systems and deposited on a
global scale. In the vicinity of industrial activity, these atmospheric depositions can
infiltrate the subsurface when rainwater recharges the aquifers and cause large-scale,
irreversible, groundwater contamination.
1.4 Spatial and temporal variations
Spatial variation in WQ is one of the main features of different types of water bodies
and is largely determined by the hydrodynamic characteristics of the water body. In
surface waters (lakes, streams, wetlands, reservoirs and rivers), WQ may vary in all
three dimensions, which are further modified by flow direction, discharge and time.
Consequently, WQ cannot usually be measured in only one location within a water
body but may require a grid or network of sampling sites. The questions to be
answered by water-quality assessment (WQA) would decide whether spatial or
temporal variation is the most important determinant needing to be monitored. The
water-quality monitoring (WQM) is then structured to cover fixed stations with
frequent samples to identify temporal variations or random locations sampled over a
short time period to identify spatial variation.
Two important features of groundwater bodies distinguish them from surface waters.
First, the relatively slow movement of water through the ground means that residence
times in aquifers are generally orders of magnitude longer than in surface waters.
Second, there is a considerable degree of physicochemical, chemical and biochemical
interdependence between the water and the material of the containing aquifer. There
is scope for WQ to be modified by interaction between the two, which is facilitated by
the long residence times.
6
Planning of water-quality monitoring systems
Box 1. Characteristics of spatial and temporal variations in WQ
Rivers
Lakes and reservoirs
Groundwater
Characteristics of spatial variations1
In fully mixed rivers variability
only in x
No variability at overturn2
In locations downstream
High variability in z for most
of confluences or effluent
systems3
discharges, variability in x and y
Usually high variability in x and y
In some multi-layer aquifers and
in the unsaturated zone, high
variability in x, y and z
High variability in x, y and z in
some irregularly shaped lakes
Characteristics of time variations
Depends on river discharge
regime
Some predictable variability
(hydrodynamic and biological
variations)
Low variability4
Medium-to-low variability in
large systems
Diurnal variation in
eutrophicated rivers
1x
Diurnal variation in
eutrophicated lakes
- longitudinal dimension; y - transverse dimension; z - vertical dimension
2
One sample can describe the whole water body
3
Two dimensions (x and z) if there is poor lateral mixing
4
Except for some alluvial aquifers and for karstic aquifers
Spatial variability differs between surface water and aquifers. It is most pronounced in
rivers and the ranges will be greater the nearer the sampling point is to the source or
sources of pollution. As the distance from the source increases, longitudinal mixing
smoothes out irregularities and fewer samples are needed to meet given confidence limits.
Thus, not only will there be a reduction in the range of variation but there will also be
dilution and some variables will be reduced by self-purification, deposition and adsorption.
These effects must be considered if a sampling station used for quality-control purposes is
located some distance from the area of point of use. Regarding groundwater, the system is
three-dimensional, with variability in all three dimensions, depending on the geological
setting of the area.
The temporal variation of the chemical quality of water bodies can be described by
studying concentrations (also loads in the case of rivers) or by determining rates such as
settling rates, biodegradation rates or transport rates. It is particularly important to define
temporal variability.
Five major types, as identified by Bartram (1996) 5 are considered here:
•
Minute-to-minute to day-to-day variability, resulting from water mixing, fluctuations
in inputs, etc., mostly linked to meteorological conditions and water-body size
(e.g. variations during river floods);
•
Diurnal variability (24-hour variations), limited to biological cycles, light/dark cycles
etc. (e.g. O2, nutrients, pH), and to cycles in pollution inputs (e.g. domestic waste);
•
Days-to-months variability, mostly in connection with climatic factors (river regime,
lake overturn, etc.) and to pollution sources (e.g. industrial wastewater, runoff from
agricultural land);
5
Bartram, 1996, 30
Chapter 1. Processes affecting water-quality and their effects
•
Seasonal hydrological and biological cycles (mostly in connection with climatic
factors); and
•
Year-to-year trends, mostly due to human influence.
1.5 7
Variability of water quality
The quality of water in various water bodies is rarely constant in time. While there may be
some relationship between the rates of change of different variables, others alter
independently. The larger the number of samples from which the mean is derived, the
narrower will be the limits of the probable difference between the observed and true
means. Variations in WQ are caused by changes (increase or decrease) in the concentration
of any of the inputs to a water-body system. Such changes may be natural or man-made
and either cyclic or random. Since it is possible for some changes to occur in combination,
the reasons behind variations may sometimes be obscured.
Random variations in the quality of water occur as a result of unpredictable events. Sudden
storms will lead to increased flows, followed by polluted runoff and leaching or to the
operation of sewer overflows. Rainfall effects may be modified by flood-control
arrangements. There may be accidental spillages and leakages. Any of these may occur at
any time and without warning.
Annual cycles may be the result of regular rainfall patterns, snowmelt and seasonal
temperature changes, among others. The seasonal growth and decay of vegetation will also
give rise to cyclical changes in the composition of the water, and rates of self-purification
and nitrification are strongly temperature-dependent. There may be daily cycles of natural
origin, particularly those caused by photosynthesis and affecting DO and pH. Industrial,
agricultural and domestic activities may cause cyclical changes due to cycles of discharge
and abstraction. Hydraulic manipulation of river flow, such as by river regulation and dam
management for power generation, navigation or other purposes, tends to be cyclical but
can occur randomly. River flows in tropical regions vary widely, especially where largescale diversions that are permanent in nature adversely affect water quality.
WQ variability in a river depends on the hydrological regime, i.e. water-discharge variability,
the number of floods per year and their magnitude, and the occurrence of low flows. During
flood periods, WQ usually shows marked variations, owing to the different origins of the
water: surface runoff, subsurface runoff (i.e. water circulation within the soil layer) and
groundwater discharge. Surface runoff is generally highly turbid and carries large amounts
of total suspended solids (TSS), including particulate organic carbon (POC). On the one
hand, subsurface runoff leaches dissolved organic carbon and nutrients (nitrogen (N) and
phosphorus (P)) from soils, whereas aquifers provide most of the elements resulting from
rock weathering. On the other hand, during low flows, a general deterioration of WQ can be
observed because of a higher concentration of pollutants.
The salinization of reservoirs in arid and semi-arid areas, where surface water is naturally
scarce, is a problem that can be aggravated by the leaching of salts from irrigated soils and
their transport in return flows to the reservoirs, as well as by highly seasonal rainfall in
these areas increasing the evaporative concentration of the ambient salinities in the water
bodies during the dry season. Sudden effects due to the acidification of water can also
occur after heavy rain and snowmelt, caused by airborne loading of different acidifying
compounds. Finally, thermal pollution of WQ is caused by the use of water as a coolant by
power plants and industrial manufacturers, when returned to the natural environment at a
higher temperature.
The various causes and origins of the deterioration of WQ that have been described above
require tailor-made approaches and solutions for the effective monitoring, management
and improvement of the quality of water bodies.
Chapter 2. The importance of water-quality monitoring
Water-quality monitoring (WQM) provides an understanding of: (a) water-quality
conditions in national streams, rivers, groundwater and aquatic systems; (b) how those
conditions vary locally, regionally and nationally; (c) whether conditions are changing
over time; (d) how natural features and human activities affect those conditions; and (e)
where those effects are most pronounced.
2.1 Main purposes of a WQM programme
Traditionally, the principal reason for monitoring WQ has been the need to verify whether
observed WQ is suitable for intended uses. Monitoring has evolved over time, however,
and the main purposes may be to:
•
Enable assessments of the current state of water quantity and quality and its
variability in space and time. Often, such assessments are appraisals of the
hydrological, morphological, physicochemical, biological and/or microbiological
conditions in relation to reference conditions, human-health effects and/or the
existing or planned uses of water. Such reference conditions may take into account
elevated concentrations of specific parameters due to “natural” geophysical and
geochemical processes;
•
Classify water in accordance with its individual pattern of physical and chemical
characteristics, determined largely by the climatic, geomorphological and
geochemical conditions prevailing in the drainage basin and the underlying aquifer;
•
Develop composite indexes6 to assess source WQ across a range of inland water
types, globally and over time;
•
Support decision-making and operational water management in critical situations.
When pollution events occur, reliable data are needed, which may require early
warning systems to signal when critical pollution levels are exceeded or toxic effects
occur. In these cases, models can often support decision-making. For transboundary
waters, information is usually gathered from the national monitoring systems (which
are established and operated according to national laws and regulations and
international agreements), rather than from monitoring systems specifically
established and operated by joint bodies7;
•
Determine trends in the quality of the aquatic environment and how the environment
is affected by the release of contaminants, by other human activities, and/or by waste
treatment operations, often known as “impact monitoring”. More recently, monitoring
has been carried out to estimate nutrient or pollutant fluxes discharged by rivers or
aquifers to lakes and oceans or across international boundaries. Background quality
6
As an example, the composite index developed by GEMS Water has a three-fold approach: (a) selecting
guidelines from WHO that are appropriate in assessing global water quality for human health; (b) selecting
variables from GEMStat that have an appropriate guideline and reasonable global coverage; and
(c) determining, on an annual basis, an overall index rating for each station using the water-quality index
equation endorsed by the Canadian Council of Ministers of the Environment. The index allowed
measurements of the frequency and extent to which variables exceeded their respective WHO guidelines at
each individual monitoring station included within GEMStat, allowing both spatial and temporal assessment
of global water quality.
7
National legislation, as well as obligations under international agreements and other commitments, should
be carefully examined in preparation for establishing, upgrading and running these systems (see Section 11.1
for details on international obligations).
Chapter 2. The importance of water-quality monitoring
9
monitoring of the aquatic environment is also widely carried out, as it provides a
means of comparing and assessing the results of impact monitoring;
•
Determine treatment options for polluted or undrinkable water;
•
Determine ecological flows;
•
Evaluate the effectiveness of water management/remedial measures;
•
To identify the low-flow conditions and estimate the compensation water flow. The
fundamental role of compensation water flow needs to be mentioned here, which,
in a river, is the link between water-quality and water-quantity problems;
•
To provide the basis of the formulation of science-based environmental policies and
also allow for evaluations of whether or not a policy has resulted in the desired
effect and been cost-effective;
•
For rational planning of pollution-control strategies and their prioritization;
•
To assess the nature and extent of pollution control needed in different water
bodies;
•
To evaluate effectiveness of pollution-control measures already in existence;
•
To evaluate water-quality trend over a period of time;
•
To assess assimilative capacity of a water body, thereby reducing costs of pollution
control;
•
To understand the environmental fate of different pollutants;
•
To assess the fitness of water for different uses.
2.2 Monitoring for management
When a WQM programme is being planned, water-use managers or similar authorities
can reasonably expect that the programme will yield data and information that will be of
value for management decision-making.
The analysis of water-management issues and objectives is the basis for specifying the
information needs. These are related to:
•
Uses (e.g. drinking-water, irrigation, recreation) and functions (maintenance of
aquatic life) of the watercourse or groundwater body that put requirements on the
quality and availability;
•
Issues (e.g. flooding, sedimentation, salinization, pollution) that hinder proper use
and functioning of the watercourse or groundwater body; and
•
Measures taken to address the issues or improve the use or functioning of the
watercourse or groundwater body, including environmental aspects.
Each country or water authority should take into account current or envisaged measures,
policies and action plans in water management. In specifying human uses and the
ecological functioning of water bodies and in identifying pressure factors, issues and
targets, the full range of qualitative and quantitative factors in river-basin management
should be considered (Box 2).
10
Planning of water-quality monitoring systems
Box 2. Examples of the relationships between uses or functions and issues in a river basin
Uses/
functions
Issues
Human Ecosystem
Recre– DrinkingIndustrial Hydro- Transport NaviFisheries
Irrigation
health functioning
ation
water
use
power medium1 gation
Flooding
X
X
Scarcity
X
X
Erosion/
sedimentation
X
X
X
X
X
X
X
X
X
Biodiversity
X
X
X
River continuity
X
X
X
Salinization
X
Acidification2
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Organic pollution3
X
X
X
X
X
Eutrophication
X
X
X
X
X
X
X
Pollution (hazardous
substances4)
X
X
X
X
X
X
X
X Major impacts on functions/uses (problematic issues)
1
2
Transport of water, ice, sediments and wastewater
Dry/wet acid deposition
3
Organic matter and bacteriological pollution in wastewater discharges
4
Hazardous substances, including radionuclides, heavy metals, toxic organic compounds and pesticides
The various functions and uses of water bodies – both ecological and human – must be
considered. Uses may compete or even conflict, particularly if water is scarce or its
quality deteriorating. A multi-functional approach tries to strike a balance between all
desired uses, including ecosystem functioning. This allows the introduction of a
hierarchy of uses, providing flexibility for the different levels of water-resource
management-policy development and for prioritization in scheduling.
Management plans should also consider various land-use issues, including
deforestation, erosion and the non-point pollution of water. They should preferably
also include an analysis of other information needs, as well as strategies for tailormade monitoring and assessment, the sharing of information among riparian countries
and assessment of the effectiveness of the measures within them.
Finally, monitoring and assessment of water quality and quantity require adequate
financial resources. Those responsible for these activities, therefore, need to
demonstrate both the benefits of monitoring for integrated water-resources
management and the possible costs, in terms of environmental degradation and other
impacts, of not monitoring. It is well known that the prevention of an environmental
problem is often less costly than its remediation. While solutions for many
environmental problems are expensive and technically challenging, what is often not
recognized is that the cost of well-designed monitoring programmes is generally much
less than either the cost of policy implementation or the monetary benefits associated
with the environmental improvement (Lovett et al., 2007). This is particularly crucial for
countries in which monitoring activities are still insufficiently funded.
Chapter 2. The importance of water-quality monitoring
2.3 11
Hydrological monitoring
As an important part of any WQM programme, all basic components of the hydrological
cycle should be measured or estimated, taking into account temporal and spatial aspects
of hydrological and hydrogeological processes (for more details, see Section 6.3).
In addition, hydrological modelling, both of surface- and groundwater and forecasting are
also a necessary component in the WQ assessment process. Operational simulation and
forecasting models have proved efficient in drainage-basin management and, in the case
of international lakes, they can play an important role. Hydrological monitoring and
modelling (of groundwater and surface water) can form supplementary elements for
linking with decision-support systems, as well as ecological modelling and assessment.
Water-level and flow forecasts should be provided daily for many functions and uses,
including water supply, navigation, ecological functions and river-channelling work, the
operation of reservoirs and flood prevention and protection. As the speed of movement of
accidental pollution in a river system depends mainly on flow characteristics, provision
should be made to use hydrological forecasts when accident or emergency warnings are
issued (see also Section 2.5). Forecasting is also important during periods of drought,
when river flows are low and the supply of water is inadequate to satisfy different users.
2.4 Types of WQM programmes
In principle, there could be as many types of monitoring programmes as there are
objectives, water bodies, pollutants and water uses, as well as any combination thereof. In
practice, assessments are limited to nine different types of operations: trend monitoring;
basic survey; operational surveillance; background monitoring; preliminary surveys;
emergency surveys; impact surveys; modelling surveys; and early warning surveillance),
as shown in Table 1. It should be noted that, in the past, many countries or water
authorities installed multi-purpose or multi-objective monitoring programmes without
conducting the necessary preliminary surveys. Critical scrutiny of results after several
years of operation has led to a second generation of programmes with more differentiated
objectives such as impact assessment, trend analysis or operational management
decisions.
For surface water, background monitoring (principally in unpolluted areas) has usually
been developed to help the interpretation of trend monitoring (time variations over a long
period) and the definition of natural, spatial variations. Models and their related surveys
have usually been set up to predict WQ for management purposes prior to pollution
treatment, or to test the impact of a new water-pollution source and are thus closely
connected to operational surveillance and impact surveys. Early warning surveillance is
undertaken for specific uses in the event of any sudden and unpredictable change in WQ,
whereas emergency surveys of a catastrophic event should be followed in the mediumand long-term by impact surveys.
As regards groundwater, monitoring normally includes the testing for long-term changes
in WQ in major aquifers so as to provide a basis for statistical identification of the possible
causes of observed conditions and to provide the statistical basis for the identification of
trends.
2.5 Early warning systems
The ability to provide early warnings is important for entire river basins which may be
affected by pollution events, including lakes and reservoirs. The effects of accidents such
as oil and chemical spills in one part of a river basin will inevitably spread downstream and
12
Planning of water-quality monitoring systems
eventually to the sea. It is therefore recommended that early warning systems covering
accidents and other emergencies should be set up for whole river basins wherever a use of
water (e.g. a water-supply intake), potentially threatened by accidental pollution, can be
safeguarded through emergency measures. River-basin early warning systems have four
main elements:
•
Accident emergency warning systems;
•
Hazard identification through databases;
•
Models to be used during emergencies; and
•
Local screening of river water.
Prior to the establishment of an early warning system8, potential sources of accidental
pollution and all available emission data should be inventoried to find out which accidental
pollutants could be threats. Risk analysis should highlight the critical risk factors to the
functions and uses of the river.
Such inventories and risk analyses should specify a list of priority pollutants to be the
subject of early warning procedures.
The establishment of an accident emergency warning system is recommended as the first
step in providing an early warning system for a river basin, which should include:
•
A network of alert centres in the river basin, where emergency messages from
national or regional authorities can be received and processed without delay on a
24-hour basis;
•
Agreements on alerting procedures;
•
A reliable international communications system through which emergency messages
can be forwarded to alert centres in riparian countries; and
•
Finally, early warnings should provide enough time for emergency measures to be
taken, both as regards surface- and groundwater pollution.
8
Section 6.2 provides additional information on this issue.
Chapter 3. Key elements of a water-quality monitoring programme
The process of water-quality monitoring and assessment is a sequence of related
activities, starting with the definition of objectives and information needs and ending with
the dissemination of the information product for use by communities, scientists and
decision-makers to effectively allow the protection and sustainable management of
national and transboundary water resources.
The structure of a WQM programme includes the following main elements:
•
Objectives;
•
Preliminary surveys:
•
Monitoring design;
•
Field monitoring operations;
•
Hydrological monitoring (surface water and groundwater);
•
Laboratory activities;
•
Quality-assurance procedures;
•
Data management and product development.
The linkage of these components is schematically summarized in Figure 1 with an
indication of the chapters where the relevant activities under each of the components are
described.
These components and their linkages need to be adequately considered during the
planning process of a WQM system, so as to ensure that the implementation of the
programme will meet with success and generate the required information products. This
planning process encompasses three main subsequent phases.
The first phase consists in defining the need for, and establishing the objectives of,
monitoring (such as in support of management or research and policy) and what WQ
issues are to be addressed. With the objectives defined, it can then be decided what data
are needed and how they will be used.
The second phase comprises the design of the monitoring programme, which should
consider and include:
•
The planning of a monitoring network with the choice of location for the sampling
operations, supported by preliminary investigations (inventories and surveys) needed
before the programme is started, so that issues, problems and risk factors can be
clearly identified and evaluated;
•
The selection of physical (e.g. temperature, suspended solids, conductivity),
chemical, biological and microbiological variables, i.e. which variables to monitor for
different uses – municipal or industrial supply, irrigation, recreation, cooling, drinkingwater supply, livestock needs etc. – and in relation to different pollution sources;
14
Planning of water-quality monitoring systems
•
The definition of sampling procedures and operations, such as in situ measurements
with different devices, manual or automated measurements, for sampling appropriate
media (water, biota, particulate matter), sample pre-treatment and conservation,
identification and shipment;
•
The planning of field measurements (frequency); and
•
The definition of the resources required for the monitoring programme, e.g. the
available national laboratory facilities, the inventory of field stations and
groundwater-observation wells, equipment and instruments, vehicles and other
Objectives (Chapters 1, 2)
• Pollutant sources
• Water uses
Institutional setting (Chapters 4, 11)
• Legislation and policies
• Administrative setting
Strategy (Chapters 1, 2, 4)
• Objectives
• Information needs
• Deliverables
Preliminary survey (Chapter 5)
• Snapshot surveys
• WQ variability
• Types of pollutants
• Technical feasibility
Resource estimation (Chapter 8)
• Laboratory facilities
• Field stations and wells
• Transport
• Staffing
Monitoring design (Chapter 5)
Network (Chapter 5)
• Station number
• Station location
• Sampling
frequency
Variables (Chapters 5, 6)
• Priorities
• Water uses
• Pollution sources
Monitoring methods (Chapter 7)
• In situ measurements
• Physical, chemical biological
laboratory analysis
Quality assurance (Chapter 9)
• Laboratories
• Fieldwork
• Quality control
Data management (Chapter 10)
• Data handling
• Data analysis
Recommended actions
• Water-use management
• Pollution control
Reporting (Chapters 10, 11)
• Dissemination
Figure 1 – Structure of water-quality monitoring operations
Chapter 3. Key elements of a water-quality monitoring programme
15
transportation means, office and field staff involved in WQ activities, humanresources development and training required, internal and external communication
needs and, finally, the estimated costs of the programme.
The third phase comprises the actual operations (implementation) of the programme, with:
(a) the setting up of a quality-assurance system at the strategic/organizational, tactical and
operational levels, essential for ensuring the reliability of information obtained by
monitoring, covering field and laboratory work, data handling and analysis, as well as the
application of WQ standards and indices; and (b) the management of data and
development of products, leading to the reporting and dissemination of results and
findings.
Chapter 4. Strategies for meeting information needs of water-quality
assessment
The monitoring of water quality to provide reliable and usable data involves many distinct
activities and can be expensive. Thus, the first step in planning the establishment of such
a system should be to define the objectives of monitoring (such as in support of
management, research or policy) and what WQ issues are to be addressed. With the
objectives defined, it can then be decided what data are needed and how they will be
used.
4.1. Establishment of objectives of the monitoring programme
In accordance with the goals, answers or information that are sought, WQM and
assessment can be looked at from different perspectives in terms of basic variables and
present status, time trends and spatial differences, uses, pollution impacts and
management needs for information for decisions and action.
All this will result in different approaches to the design and implementation of monitoring
programmes, the selection of variables to be measured, the frequency and location of
measurements, the additional information needed for interpretation and the way in which
information is generated and presented to meet particular information requirements.
When establishing monitoring objectives, the intended uses of the water are particularly
important. The environment, aquatic life, drinking-water sources and bathing areas require
high-quality requirements, while navigation and water for cooling of industrial processes
or cold/heat storage have lower-quality requirements. In the case of livestock watering,
irrigation, boiler water and fisheries, each demands a specific level of quality and has its
own relative economic importance. To help with the establishment of objectives, the
following questions might be addressed:
•
Why is monitoring going to be conducted? Is it for basic information, planning and
policy information, management and operational information, regulation and
compliance, resource assessment, or other purposes?
•
What information is required on WQ for various uses? Which variables should be
measured, at what frequency and in response to which natural or man-made events?
•
What is practical in terms of the human and financial resources available for
monitoring? (There is little point in setting unrealistic objectives.)
•
Which agency is responsible for the different elements of monitoring?
•
Who is going to use the monitoring data and what is the intended use of the
information?
•
Will monitoring results be used to support management decisions, ensure
compliance with standards, identify priorities for action, provide early warning of
future problems or detect gaps in current knowledge?
A list of monitoring objectives that might be used as the basis for the design of sampling
networks, was identified by Bartram (1996) 9, and is shown in Box 3. It is not intended to be
exhaustive but merely to provide some examples.
9
Bartram, 1996, 38-39.
Chapter 4. Strategies for meeting information needs of water-quality assessment
17
Box 3. Typical monitoring objectives
• Identification of baseline conditions in the watercourse system
• Detection of any signs of deterioration in WQ
• Identification of any water bodies in the watercourse system that do not meet the desired
WQ standards
• Identification of any contaminated areas (surface- and/or groundwater)
• Determination of the extent and effects of specific waste discharges
• Estimation of the pollution load carried by a watercourse system and groundwater
• Estimation of the polluting status and its trends in the water body in order to evaluate the
effectiveness of a WQM intervention
• Development of WQ guidelines and/or standards for specific water uses
• Development of regulations covering the quantity and quality of waste discharges
• Development of adequate quality assurance/quality control (QA/QC) processes
• Development of a water-pollution control programme
It is particularly important that the objectives are clearly stated and recorded. Written
objectives are an effective way of communicating with sponsors and provide assurance
that the monitoring programme has been systematically planned. They are also important
when the programme is being evaluated to determine whether or not the objectives are
being met.
It is rare for a monitoring programme to have a single objective. Programmes and projects
may combine multiple objectives and the data used for different purposes. The
implementation of the WQ assessment programme objectives may focus on: (a) regular
monitoring with good spatial distribution of quality (high number of monitoring stations);
(b) trends (high sampling frequency); or (c) pollutants (in-depth inventories). The focus
may also be on a snapshot or near-real-time monitoring of selected variables or on an
interest in transport of the load or mass of contaminants (fixed-station moderate sampling
frequency). Full coverage of all these requirements is virtually impossible and very costly.
Consequently, preliminary surveys are necessary to determine the focus of an operational
programme (see Section 5.2).
Countries with economies in transition often stress their difficulties in complying with the
recommendations of monitoring and assessment guidelines to enable them to collect the
type of data which permit useful assessment and coherent environmental management
and which can guide investment decisions. To make the best use of available resources
and knowledge, a step-by-step approach is often recommended. This entails identifying
and agreeing on priorities for monitoring and assessment and progressively proceeding
from general appraisal to more precise assessments and from labour-intensive methods to
higher-technology ones.
4.2. Water-quality monitoring information needs
The specific purpose of the water must be the initial concern when determining the
monitoring information required and no programme should be started without critically
scrutinizing the real needs for quality information. Since water resources are usually put to
several competing uses, monitoring should reflect the data needs of the various water
users involved. These can be grouped into three large categories: communities, scientists
and decision-makers. The availability of information accessible to the public and decisionmakers is a vital pre-condition for the protection and sustainable use of national and
transboundary waters and the support of decision-making.
18
Planning of water-quality monitoring systems
Definition of information needs
A WQ system should be designed so that it can provide information at all levels,
i.e. international, national (federal), regional and local. The requirement for additional
information coming from other programmes or agencies will also define the level of
assessment to be undertaken. The national (or federal) level can include data taken from
other agencies, as well as from regional and local levels. It is necessary to define clearly
what information is needed and already available and to identify gaps that need to be
filled. Objectives which are too vague, information needs which are inadequately analysed
and information gaps which are poorly identified could result in the production of
non-useful data.
To specify information needs, information users and producers should interact closely,
with the direct involvement of the institutions responsible for protection and sustainable
use of the water bodies. The needs should be specified, based on an analysis of the water
management of a river basin and the subsequent identification of relevant issues. A
distinction should be made between information used for: (a) policy preparation or
evaluation; and (b) operational water management. Inventories and preliminary surveys
can help significantly in the process of problem identification and specification of
information needs (see also Section 5.2).
In summary, the specified information needs should lead to the definition of:
•
Appropriate variables to be monitored;
•
Criteria for assessment (e.g. indicators, early warning criteria for floods or accidental
pollution);
•
Specified requirements for reporting and presenting information (e.g. presentation in
maps, graphs, geographical information systems (GIS), degree of aggregation);
•
Relevant accuracy for each monitoring variable;
•
Degree of data reliability;
•
Specified response time (the period of time within which the information is needed),
such as for flood forecasts or early warning systems (e.g. minutes/hours), for trend
detection (e.g. number of weeks after sampling), for survey of groundwatercontamination plume (e.g. months/years), etc.; and
•
Priority of the information (e.g. if the same information need arises from a variety of
water problems, collecting it once makes it possible to address a variety of issues).
All this will allow the adequate design of a monitoring and assessment programme. The
relevant accuracy and the degree of data reliability are decisive factors in the selection of
monitoring sites, the determination of monitoring frequencies and the choice of
technology and methodologies for data management.
Risk assessment can also be used to determine whether the chosen monitoring strategy will
fully meet the information needs. Statistical modelling to help optimize monitoring design
(spatial density and sampling frequency) implies an element of risk analysis. For example, it
provides information on whether the resulting decreased level of information will still meet
all previously specified information needs should either density or frequency be reduced.
Integrated water-management strategies
While strategies should be developed and become integrated with effective land
management and the linkages between water systems and the atmospheric system must
Chapter 4. Strategies for meeting information needs of water-quality assessment
19
be given more attention, WQ cannot be isolated from water quantity (see also Section 2.2).
The current direction is that regional/national river WQM networks, groundwater-quality
networks and associated databases should be designed and operated in parallel with those
for water quantity. Ideally, they should be managed together.
It should also be recognized that continuity is needed in order to produce time-series that
make it possible to detect significant and reliable trends. Environmental monitoring
programmes should always be seen as requiring long-term commitment. This is especially
the case for groundwater as processes (groundwater flow and chemical reactions) in the
subsurface take much more time than in surface water.
4.3 Legislation and administrative setting
In general, national legislation sets out obligations and responsibilities for relevant
agencies, such as hydrometeorological services, environmental and health agencies,
geological surveys and operators of water-regulation structures and industrial installations
to monitor and assess various components of the environment and report on the results.
As river basins usually stretch over different administrative and geographical units and
State borders, cooperation between actors is needed. Hydrometeorological services play
an essential role in providing water-quantity data and early warning information for
extreme hydrological events. Organizations which operate response systems for
emergencies involving water-regulation structures and industrial plants are important
partners in providing data to mitigate the adverse impacts of failures of such installations.
Industrial enterprises that monitor their own water abstractions and wastewater
discharges provide data for compliance purposes (in some countries, this part of the
national WQM network is substantial). Assessment of watercourses and groundwater
bodies also requires socio-economic data, including population and economic statistics,
which are collected by statistical offices.
Where WQ legislation is weak or non-existent, the water authority’s mandate may be to
develop legislation and regulations appropriate to the country’s economic development
plans. In this case, the monitoring objectives will probably focus, in the first instance, on
acquiring background information on WQ. The objectives will change as information on
WQ is accumulated, as problems emerge and solutions are developed and as new
demands are made on the water resources. As a rule, national assessment systems are
designed and operate under the supervision of government agencies responsible for
environmental protection and the rational use of water resources, often with the active
participation of research institutions belonging to these agencies. In a number of
countries, however, there are several government agencies which are responsible for
different aspects of WQ protection and management. In this case, the government
normally appoints the particular agency responsible for the organization of the national
assessment system. Although the legal framework comes from the government, the
monitoring and interpretation of results can be outsourced in some cases and carried out
by private companies, provided the quality-assurance and public access procedures are in
place.
Multilateral environmental agreements (such as the United Nations Economic Commission
for Europe (UNECE) conventions and protocols, European Union directives), as well as
transboundary-water agreements, contain obligations for countries to monitor and assess
watercourses and to report, as appropriate, to a specific body, such as an international
commission, secretariat or organization (see Section 11.1). In January 2009, a resolution
was adopted by the United Nations on the law of transboundary aquifers, recommending
States to make appropriate bilateral or regional arrangements for the proper management
of their transboundary aquifers on the basis of the principles enunciated in the articles
(resolution A/RES/63/124). Such cooperative arrangements and institutional frameworks
greatly influence the efficiency of monitoring and assessment and can help in the planning
phase of the national WQM network.
Chapter 5. Design of a monitoring programme
With the objectives of the WQM programme defined and the decision taken on what data
are needed and how they will be used, the sampling locations and frequencies are then
chosen with a view to obtaining the required information, while ensuring that the
resources are employed to best advantage.
5.1 Planning a monitoring network
A monitoring programme commonly covers the watercourse system of a catchment10 area
(i.e. a main river and all its tributaries, streams, brooks, ditches, canals, etc., as well as any
lakes or ponds that discharge into the river or tributaries) or it can comprise an
administrative unit, e.g. a province. In some cases, groundwater enters the watercourse
system from an aquifer or a system of aquifers, all or part of which may lie outside the
topographic one. Surface and groundwater catchment areas often do not coincide.
The level of detail that monitoring can provide depends on the density of the network, the
frequency of sampling, the size of the basin and the issues under investigation. For
example, when a station at the outlet of a river basin reports WQ changes, a more detailed
monitoring network is often needed to reveal the source, causal agent and the pathways of
pollutants. The interaction between surface and aquifers may also be different in the upper
and lower parts of the basin. In these cases, information is needed for smaller sub-basins.
The different sources of WQ pollution, such as point source (e.g. sewage, industrial
leakage to subsurface) or non-point sources (e.g. agricultural runoff/percolation) also need
to be considered.
The monitoring and assessment of groundwater quality is often more complicated
because of: (a) the complex structure and composition of aquifers; (b) the recharge and
abstraction conditions of the aquifer; and (c) the relatively long timescales of groundwater
movement and residence.
Monitoring networks, the frequency of measurements, the selection of parameters, as well
as assessment methodologies, should be adapted to all these conditions. To facilitate this,
a conceptual model of the river basin might be developed, so that the whole system is well
understood, establishing whether interactions between surface- and groundwater exist or
not, so that water quantity and quality can be taken into account.
Monitoring alternatives
At the planning stage, the following alternatives should be considered:
•
Fixed-site network, useful for public information and broad policy issues; should be
limited to drinking-water sources that require regular monitoring;
•
Flexible survey approach, more convenient for regulatory purposes, determining
management options in cases of pollution and related investment decision-making;
•
Decentralized monitoring alternatives instead of a national network operated by a
central agency; and
10
The catchment area is defined as the area from which all water flows to the watercourse. The land surface
that slopes in such a way that precipitation falling on it drains towards the watercourse is called the
topographic catchment area.
Chapter 5. Design of a monitoring programme
21
Monitoring of the quality of the aquatic environment should be coupled with the
appropriate hydrological monitoring.
•
When starting a monitoring programme, it is better to have a complete record of reliable
data concerning WQ at a few sampling stations rather than many data of questionable
quality from many sampling stations. When reported data are not reliable, the programme
and its staff will lose credibility and poor or incorrect decisions may be made with
potentially serious and costly consequences.
5.2 Selection of sampling stations
Processes affecting water quality and their impacts should be taken into account when
sampling sites are selected. This requires consideration of: (a) the monitoring objective(s);
(b) some knowledge of the geography of the watercourse system; (c) actual and potential
water uses; (d) actual and potential sources of pollution; (e) water-control operations; and
(f) local geochemical conditions and type(s) of the water body/bodies. In many cases, the
precise location of a sampling station can be made only after a field investigation (see
Section 5.3).
In the specific case of groundwater-monitoring programmes, the fundamental requirement
is to define the distribution of water quality in three dimensions. This requirement is the
same, regardless of the specific objectives of the programme. Thus, in all cases, the
objective is to obtain representative samples which fully reflect the conditions of the
groundwater in situ at a specific point, periodically at known times. Having established the
objectives of quality assessment, the next step is to design the sampling network. This is
essentially a function of the sampling-point type, density and location, sampling method
and frequency and choice of parameters (see also Annex 1, Section 6).
The essential factors to consider for the location of sampling sites, among others, are
described in the field operations manual for WQM (WMO, 1988)11.
As regards the types of sampling sites, the GEMS/Water global monitoring network12
defines the following three types of monitoring station:
•
Baseline stations are typically located in headwater lakes, undisturbed upstream river
stretches, and in aquifers where no known direct diffuse or point-sources of
pollutants are likely to be found. They are used to establish the natural water-quality
conditions; provide a basis for comparison with stations having significant direct
human impact (i.e. trend and global river-flux stations); and determine, through trend
analysis, the influence of long-range transport of contaminants and climatic changes;
•
Trend stations are typically located in major river basins, lakes or aquifers. They are
used to follow long-term changes in water quality related to a variety of pollution
sources and land uses and provide a basis for the identification of causes or
influences on measured conditions or identified trends. Since trend stations are
intended to represent human impacts on water quality, the number of trend stations
is relatively higher than the other categories of stations, in order to cover the variety
of water quality issues facing various basins. Ideally, each country should cover all
major human influences on water quality. Most of the stations are located in basins
with a range of pollution-inducing activities. Some stations, however, are located in
basins with single, dominant activities. Some trend stations may also serve as global
river-flux stations;
11
WMO Manual on Water Quality Monitoring, 1988; WMO Operational Hydrology Report, No. 27, WMO-No. 680,
World Meteorological Organization, Geneva, 197 pp.
12
Verbatim GEMS/Water, 2005, 12
22
Planning of water-quality monitoring systems
Flux stations are located at the mouth of rivers as they exit to the coastal
environment. They are used to determine integrated annual fluxes of critical
pollutants from river basins to oceans or regional seas, thereby contributing to
geochemical cycles. For the calculation of chemical fluxes, it is essential that waterflow measurements be obtained at the location of the global river flux stations. It is
for this reason that station co-location is encouraged with those designated stations
of WMO’s Global Runoff Data Centre (GRDC) (see Section 11.2).
•
Finally, in large programmes involving several parties, institutional issues are important.
Sampling sites may be operated by different entities that might not be cooperating. Such
issues should preferably be resolved in the early stages in order to streamline national
monitoring and enable the best possible data-sharing.
5.3 Preliminary surveys
Preliminary investigations such as inventories and surveys are needed before any
monitoring programme is started, so that issues, problems and risk factors can be clearly
identified and evaluated with the overall aim of establishing the monitoring systems as
effectively as possible. These are short-term, limited activities to determine WQ variability,
specific issues in lakes, river basins and groundwater, the type of monitoring media and
pollutants to be considered and the technical and financial feasibility of a complete
monitoring programme. Inventories and in-depth surveys should provide: (a) relevant
background information with respect to the uses of water; (b) the possible presence of
pollutants not previously monitored; (c) toxicological factors; (d) the natural background
concentrations of components in groundwater; and (e) the spatial and temporal variability
of pollutant distributions. Finally, national surveys, together with land-use maps, can
provide a rapid overview of possible pressures in the basin. In this context, it is useful to
consider homogeneous areas where these preliminary investigations are to be undertaken.
Inventories should bring together all the available data, even when scattered around
different agencies or institutions. This can involve the registering of historical data,
licenses, etc. in administrative databases, as well as a general screening and interpretation
of all the relevant information. For inventories of pollution sources, this will involve
examining information at source, such as figures concerning production processes and the
use of raw materials, as well as the investigation of suspect incidents through additional
questioning.
WQ surveys provide a preliminary insight into the functioning of the aquatic ecosystem,
the geochemical characteristics of groundwater and the occurrence of pollution and
toxicity in water. The ecological status of a river, lake or estuary can be assessed by
investigating the qualitative and quantitative structures of the biotic13 components of the
ecosystems. Chemical screening of surface water, sediment and effluents at hot spots and
key locations can be performed with the supporting analyses. Any specific target
compounds that inventories suggest might occur can also be analysed and toxic effects in
surface water. Sediments and effluents can also be investigated at such locations.
Preliminary surveys also help to refine the logistical aspects of monitoring. For example,
access to sampling stations is tested and can indicate whether refinements are necessary
to the site selection (a certain site may be found impractical for a variety of reasons,
e.g. transport difficulties). Similarly, operational approaches may be tested such as on-site
testing techniques or sample preservation and transport methods can be evaluated.
Sample volume requirements and preservation methods can then also be refined.
13
Phytoplankton, macrophytes, the macroinvertebrate community, fish populations
Chapter 5. Design of a monitoring programme
23
As a final result of the inventory, a listing of sampling sites should be prepared and
sampling stations or wells selected during the design of the monitoring programme (see
also Section 8.2).
5.4 Documentation
During the design phase of a WQM programme, it is essential that full documentation is
compiled. This should initially cover the description of a monitoring area comprising, as a
minimum: (a) the definition of the extent of the area where water conditions are to be
monitored; (b) a summary of the environmental conditions and processes (including
human activities) that may affect WQ; (c) the availability of meteorological and
hydrological information; (d) a description of the existing water bodies; and (e) a summary
of actual and potential uses of water. Subsequently, the initial steps of the planning
process should then be recorded, starting with the monitoring objectives through the
choice of sampling locations.
Additional guidelines on documentation requirements are provided in Section 10.3.
Chapter 6. Selection of water-quality variables
The parameters which characterize WQ comprise physical properties, redox conditions,
inorganic and organic chemicals and biological components (both microbiological and
macrobiotic), which can indicate the ecological health of the aquatic environment. The
parameters selected for evaluation at a station or observation well will be determined
largely by the objectives of the monitoring programme.
Water bodies can be fully characterized by the three major components: hydrodynamics,
physicochemistry and biology. A complete assessment of WQ therefore needs to be based
on appropriate monitoring of these components.
The selection of variables for any WQ assessment programme should be indicative of
functions and issues in river basins. The selection must therefore consider known
characteristics of the water resource and the polluting sources. The purpose of this chapter
is to provide information to assist the selection of variables, i.e. which variables to monitor
for different uses (municipal or industrial supply, irrigation, recreation, cooling, agriculture,
drinking-water supply, livestock needs, etc.) and in relation to different pollution sources.
6.1 Classification of WQ variables
Annex 1 provides a detailed description of the main WQ variables, ranging from: general
variables, such as nutrients, organic matter and major ions; other inorganic variables, such
as metals and organic contaminants; and biological variables, such as microbiological
indicators and sedimentation.
The WQ variables may be listed, grouped and classified in different ways14. As an example,
a number of broad categories under which parameters may be grouped are shown in Box 4.
River-basin management and water-pollution control have long relied on aggregate
parameters, such as biochemical oxygen demand (BOD) and chemical oxygen demand
(COD), indicators widely used to assess the amount of organic oxygen-consuming
pollution in rivers. For human consumption and public water supply, a set of
microbiological indicator organisms (e.g. faecal coliform bacteria) have been identified and
are now commonly applied to determine the hygienic suitability of water for drinking.
Typically, drinking-water quality is assessed by comparing water samples to drinkingwater quality guidelines or standards. Many countries set such guidelines, based on those
of the World Health Organization (WHO) and may modify or tailor them to their domestic
context. Appendix 1 provides a summary of international and national WQ guidelines and
standards by a number of international organizations (WHO, EU) and selected countries15
(see also Section 9.6).
14
In the GEMS/Water publication Water Quality for Ecosystem and Human Health (2006), the parameters are
described following water-quality categories: physical and chemical characteristics of a water body, major
ions, nutrients, metals, organic matter, biological components, organic contaminants and hydrological
variables. The variables and indices according to the definition of “ecological status” in the EU Water
Framework Directive (WFD) are grouped as follows: chemical and physicochemical elements, biological
elements, harmful substances, microbiological quality and sediments.
15
Australia, Canada, New Zealand, Japan and USA
Chapter 6. Selection of water-quality variables
25
Box 4. Categories of WQ parameters
• Basic parameters, e.g. water temperature, pH, conductivity, DO and discharge, used for a general
characterization of WQ
• Suspended particulate matter, e.g. suspended solids, turbidity and organic matter (total organic
carbon (TOC), BOD and COD
• Indicators of pollution with oxygen-consuming substances e.g. DO, BOD, COD and ammonium
• Indicators of pollution with nutrients and eutrophication effects, e.g. nitrogen and phosphorus,
and various biological effect variables, e.g. chlorophyll and Secchi-disc transparency
• Indicators of retention time in a slow-changing water body (lakes, reservoirs, impoundments)
• Indicators of acidification, e.g. pH, alkalinity, conductivity, sulphate, nitrate, aluminium,
phytoplankton and diatom sampling
• Indicators for forecasting the future eutrophication state of water bodies
• Specific major ions, e.g. chloride, sulphate, sodium, potassium, calcium and magnesium: these
are essential factors in determining the suitability of water for most uses, such as public water
supply, livestock watering and crop irrigation
• Specific minor ions, e.g. arsenic and fluoride: above certain concentrations, these ions are toxic
to human health
• Metals, e.g. cadmium, mercury, copper and zinc
• Organic micropollutants, such as pesticides and the numerous chemical substances used in
industrial processes, products and households
• Indicators of radioactivity, e.g. total alpha and beta activity, 137Cs, 90Sr
• Microbiological indicator organisms e.g. total coliforms, faecal coliforms and faecal streptococci
bacteria
• Biological indicators of the ecological quality, e.g. phytoplankton, zooplankton, zoobenthos, fish
and macrophytes
A wealth of information (including parameters, pressures in the basin, variability,
sampling, instrumentation, usage, standards, advantages, disadvantages and
recommendations) on the key features of each chemical and physicochemical, and
biological quality element for lakes can be found in Appendices 2 and 3, respectively.
6.2 Selection of variables
The variables to be measured as part of any given sampling programme should reflect a
consideration of the uses to which the water is put, as well as any known or anticipated
impacts on the water quality. In addition, the selection of variables to be included in a WQ
assessment should be related to the objectives of the programme. Assessments can be
divided broadly into two categories – use- and impact-orientated – as described below.
They can, however, also be based on the widely accepted DSPIR16 (Drivers-PressuresState-Impact-Responses) framework to guide state and trend assessments of surface- and
groundwater ecosystems, shown in Table 3. The following services and uses are covered:
human health and drinking-water, agriculture, municipal/industrial, energy, ecosystem
stability, structure and health, and tourism and recreation.
For many variables, existing literature on their occurrence in the environment, and
particularly in freshwater systems, can provide guidance in prioritization. As an example,
the revised list of basic variables used in the GEMS/Water programme (e.g. stations in
rivers, lakes/reservoirs, aquifers and global river-flux monitoring stations) are presented in
Table 2.
16
UNEP GEMS/Water Technical Advisory Paper No. 2, May 2005
26
Planning of water-quality monitoring systems
There may be a need for those responsible for assessments to decide which monitoring
activities have the highest priority. By using risk-assessment techniques (and recording
how these were applied), this could be done using the concept of “expected damage”,
i.e. determining what goes wrong when there is insufficient information because of lack of
monitoring, or what losses are incurred when less-than-optimal decisions are made as a
result.
Selection of variables in relation to water use17
Use-oriented assessment indicates whether WQ is satisfactory for specific purposes, such
as drinking-water supply, industrial use or irrigation. Many water uses have specific
requirements with respect to physical and chemical variables or contaminants. In some
cases, therefore, the required quality of water has been defined by guidelines, standards or
maximum allowable concentrations (see summary in Appendix 1).
These consist of recommended (as in the case of guidelines) or mandatory (as in the case
of standards) concentrations of selected variables which should not be exceeded for the
prescribed water use. Existing guidelines and standards define the minimum set of
variables for inclusion in assessment programmes. Table 4 presents a selection of
variables for assessment of WQ in relation to non-industrial water use, covering
background monitoring, aquatic life and fisheries, drinking-water sources, recreation and
health, agriculture, irrigation and livestock watering. The suggested variables are
appropriate to the specific water uses and can be used where guidelines are not available.
The selection should include only those most appropriate to local conditions and it may be
necessary to include other variables not indicated under the respective headings.
Other variables can also be monitored, if necessary, according to special conditions related
to the intended use. Acceptable WQ is also related to water availability. When water is
scarce, a lower level of quality may have to be accepted and the variables measured can be
kept to a minimum.
The requirements of industry for WQ are diverse, depending on the nature of the industry
and the individual processes using water within it. Table 5 summarizes some of the key
variables for some major industrial uses or processes, such as heating, cooling, power
generation, iron and steel, pulp and paper, petrol and food processing. Although some
proposed guidelines exist, they need to be considered in relation to the specific industrial
needs and water availability.
Selection of variables in relation to pollutant sources18
WQ assessment often examines the effects of specific activities on WQ. Typically, such an
assessment is undertaken in relation to effluent discharges, urban or land runoff or
accidental pollution incidents. The selection of variables is governed by knowledge of the
pollution sources and the expected impacts on the receiving water body. It is also desirable
to know the quality of the water prior to anthropogenic inputs. This can be obtained, for
example, by monitoring upstream in a river or prior to the development of a proposed
waste-disposal facility. When this cannot be done, background WQ from an adjacent,
uncontaminated, water body in the same catchment can be used.
Appropriate variables for assessing WQ in relation to several major sources of pollutants
are given in Table 6, which shows a selection of variables for the assessment of WQ in
relation to non-industrial pollution sources, comprising sewage and municipal wastewater,
urban runoff, agricultural activities, waste disposal to land, solid hazardous municipal
chemicals and long-range atmospheric transport. Table 7 provides information on the
17
Taken mainly from D. Chapman [Ed.], 1996
18
Taken mainly from D. Chapman [Ed.], 1996
Chapter 6. Selection of water-quality variables
27
selection of variables for the assessment of WQ in relation to some common industrial
sources of pollution. These cover food processing, mining, oil extraction/refining,
chemical/pharmaceutical, pulp and paper, metallurgy, machine production and textiles.
There are also accidents related to leakage to groundwater, e.g. at petrol stations.
The suggested variables for different types of assessment given in this section are based
on common situations and should be considered as guides only. The final selection
depends on the products manufactured or processed, together with any compounds
present in local industrial effluents. Any standards or guidelines for specific variables
should also be taken into account. The full selection of variables must be made in relation
to assessment objectives and specific knowledge of each individual situation.
Most of the variables can be measured by various methods and techniques, depending on
the resources available, time constraints (how quickly the results are needed) and the
accuracy of the results required. These issues will be discussed in Chapter 7.
Selection of variables for early warning systems19
The appropriate indicative variables to be monitored for early warnings will vary and
should be selected on the basis of:
•
The past history of pollution emergencies (frequently occurring local risk substances);
•
Issues specific to the river basin (e.g. DO, pH);
•
Any additional need to detect specific micropollutants, such as heavy metals, harmful
organic compounds or pesticides, using advanced technologies; and
•
Any additional need to detect specific micropollutants which may accumulate in living
organisms and generate chronic diseases.
Variables should also be selected for early warning systems according to the availability of
equipment for in situ measurements and other cost-benefit considerations, due to the high
investment, operating and maintenance costs for automatic measuring devices. Acute
toxic effects may also be recognizable with the help of biological systems examining
species from different trophic levels and with various functions.
Any potentially hazardous pollutants that frequently occur in a river basin in
concentrations that may jeopardize water uses should be targeted by early warning
systems. Simple indicative parameters such as DO, pH or oily substances can be routinely
measured by automatic in situ sensors. If specific problematic micropollutants such as
pesticides need to be detected, more advanced analytical systems can be used, although
investment, operating and maintenance costs are high. Toxicological effects in organisms
at various trophic levels can be measured with automated biological early warning
systems.
Early warnings should provide enough time for emergency measures to be taken. The
location of early warning WQM sites, including their observational infrastructure (stations),
should therefore be determined with regard to the response time (the interval between the
moment of sampling and the issue of an alarm) and the time any contaminant plume in a
river will take to flow from the warning station to any site downstream where the water is
used, such as a water-supply intake. The diffusion of contaminants may be crucially
affected by high river discharges. Sampling points should also be carefully located to
ensure that the presence of all the relevant pollutants is observed.
19
See also Section 2.5.
28
Planning of water-quality monitoring systems
The frequency of measurements should be determined by the expected size of
contaminant plumes so that no significant pollution is missed. Plumes will inevitably
disperse to some extent between their discharge source and the sampling location,
according to the characteristics of the river. Furthermore, sampling frequencies should
allow sufficient time for action to be taken in the event of an emergency. Additional and
intensified sampling is recommended after the first indication of accidental pollution. One
example of a river-basin alarm system is that of the River Rhine.
Regarding contamination plumes in groundwater, observations wells should be monitored
at specific locations to verify that the plume is not reaching some potential receptors such
as deeper aquifers, rivers or the surrounding groundwater system.
6.3 Hydrological variables
The main hydrological and hydrometeorological characteristics, such as precipitation,
snow cover, water level, river flow, sediment discharges (suspended sediment and bed
load), evaporation and evapotranspiration, soil moisture, recharge, groundwater head20,
temperature and data on ice conditions, should also be measured and estimated as an
important part of any WQM programme.
In general, a sufficient number of hydrological or river gauging stations should be located
along the main river to permit interpolation of water level and discharge between the
stations. In addition, water balances require sufficient observation stations at small
streams and tributaries. Gauges on lakes and reservoirs are normally located near their
outlets, but sufficiently upstream to avoid the influence of drawdown. Continuous riverflow records are necessary in estimating the sediment or chemical loads of streams,
including pollutants.
Regarding groundwater, a sufficient number of observation or monitoring wells should be
set up through the area at specific locations. As groundwater quantity and quality have to
be defined in three dimensions, measurements and sampling should also take place at
different depths, which should be chosen according to the characteristics of the aquifer
system.
The factors controlling the water balance of a lake should either be measured directly or
calculated by means of regional assessment or the water-balance equation. For the latter,
the key hydrological variables are typically regional precipitation, lake inflow, lake-water
level and evaporation and lake outflow. Measurement of water level is necessary for
mass-flow calculations in lakes and aquifers and must be measured at the time and place
of water-sampling. Snow cover and groundwater storage are also important factors in
many cases. Important physical hydrological phenomena, such as sediment transport,
erosion, water temperature and ice phenomena, can also affect chemical and biological
processes in lakes.
The morphological characteristics of the lake itself are of key importance. A bathymetric
map – preferably in a data system format – can be used for the definition of the
morphological features, as well as for various physical, chemical and biological studies.
The velocity (sometimes referred to as the flow rate) of a water body can significantly
affect its ability to assimilate and transport pollutants. Thus, measurement of velocity is
extremely important in any assessment programme. It enables the prediction of
movement of compounds (particularly pollutants) within water bodies, including aquifers.
20 Groundwater
head is the water pressure expressed in units of length measured in a well. The distribution of
hydraulic head determines the direction of groundwater flow.
Chapter 6. Selection of water-quality variables
29
For example, knowledge of water velocity enables the prediction of the time of arrival
downstream of a contaminant accidentally discharged upstream. Regarding groundwater,
the flow velocity enables the prediction of the time of arrival of the contamination or a
derived one to a production well.
Finally, hydrological modelling and forecasting are a useful component in the WQ
assessment process. Modelling the hydrological cycle of a river system is a relatively
straightforward process. Operational simulation and forecasting models have proved
efficient in drainage-basin management and, in the case of international lakes, can play an
important role. Hydrological monitoring and modelling can form supplementary elements
for linking with decision-support systems, as well as ecological modelling and assessment.
As the speed of movement of accidental pollution in a river system depends mainly on
flow characteristics, provision should be made to use hydrological forecasts when accident
or emergency warnings are issued.
Flood forecasting is more intensive and requires more frequent observations and data
transmission. More observation sites and a wider range of information (e.g. on reservoir
operation, dyke failures and emergency measures) are needed. Forecasts can then be
issued more frequently and include additional characteristics, such as the timing and
magnitude of flood peaks.
Some important water-use data can be calculated by using hydrological observations.
Examples include flows at industrial or municipal intakes and outlets, releases from
reservoirs and other main diversions to and from lakes. This information can be used for
lake regulation or the allocation of water during extreme situations or normal operations.
Low-flow conditions can disrupt the use or consumption of water and the ecological status
of a water body. Long-term series of data on hydrological parameters and the
corresponding climatic factors are needed for the statistically reliable estimation of
drought conditions. During droughts, more frequent exchange of information and data on
reservoir operation, diversions and water uses may be necessary, in addition to
hydrological and meteorological data. In this regard, it is suggested that suitable methods
be developed or adopted in order to calculate or – at least to evaluate –the compensation
water flow that is required as minimum flow to maintain a healthy river environment.
Chapter 7. Selection of water-quality monitoring methods and
techniques
There are a variety of monitoring methods and different levels of technology (from
low-cost to very expensive instruments) and techniques available and being developed to
address the quality of water resources around the globe. There is no single, simple
method which can be applied across the board, in every aquatic situation. The challenge
for water managers is in the efficient use of a mixture of technologies specifically to
address each particular situation.
7.1 Methods for field monitoring
Traditionally, water-sampling operations include in situ measurements, sampling of
appropriate media (water, biota and particulate matter), sample pre-treatment and
conservation, identification and shipment. The various alternative methods that may be
chosen are shown in Box 5. Protocols to ensure the comparability of results and to prevent
sample contamination should be established for all monitoring methods.
Box 5. Methods for field monitoring*
•
•
•
•
•
•
•
•
•
•
In situ measurements with different devices
Manual or automated measurements
Continuous or snapshot monitoring
Water-sampling, including grab sampling
Depth-integrated sampling
Time-proportional composite sampling
Space-composite sampling
Water-quality kits
Vacuum-pumping techniques
Remote-sensing
* For more details, see Annex 2.
Methods of measuring are determined by a number of factors: the type of material
being monitored – surface- or groundwater; bottom or suspended sediment;
groundwater-well sampling; the type of sample – grab, composite or integrated; the
quality parameter being analysed; the amount of sample; whether the sample is
analysed on the spot or sent back to a laboratory.
This chapter 21 summarizes the different monitoring methods and their main
advantages and disadvantages. The purpose is to give guidelines so that the manager
may be able to choose the most suitable (reliable, cost-effective) methods for the
monitoring programme. The process of choosing the variables to be monitored and
the methods to be used is iterative, since certain variables may be difficult or
expensive to monitor and alternative solutions have to be found.
The methods employed to measure the selected variables depend on access to
sampling equipment and reagents, availability of technical staff and their degree of
expertise and the level of accuracy required by the objectives of the programme.
Detailed descriptions of sampling and analytical methods are available in a number of
21 A
detailed description of the main water-quality monitoring methods and techniques is provided in
Annex 2.
Chapter 7. Selection of water-quality monitoring methods and techniques
31
guides and reference material published by various authors, international
organizations and national agencies. 22
Traditional water-sampling for laboratory chemical and biological analysis provides
accurate results if performed with care and sufficient quality-assurance procedures
are used. In many cases, they are also the only acceptable method when high
precision is required. Laboratory analyses may, however, be expensive and
time-consuming.
Existing groundwater-quality assessment programmes with a range of objectives
depend entirely on samples taken from the pump discharge as it comes to ground
level. Samples from boreholes and wells are the basis of background and trendmonitoring programmes. Existing boreholes selected for such programmes should be
those with the most reliable information, so that a short screen length over the most
appropriate depth interval of aquifer and most comprehensive geological log, facilitate
subsequent interpretation of the results.
In situ monitoring may be either manual or automated and has to be selected on the
basis of specific monitoring objectives, programme resources and suitability of sites.
The method selected must be appropriate for programme goals and technically
feasible. Automated methods may be more appropriate than manual ones in situations
where:
•
Highly variable WQ occurs in an hourly/daily time frame;
•
Infrequent transient events occur and affect WQ; or
•
It is not possible to sample manually or it is difficult to maintain the required
sampling frequency.
WQM equipment
In situ and portable WQM devices are often used as there is an increasing need to
monitor large areas in short time intervals. These devices and methodologies can
range from simple, inexpensive devices to capital-intensive, sophisticated equipment.
Field measurements reduce the time between sampling and measuring, allowing for
real- or near-real-time analyses.
There are instruments for simple field-measured variables such as thermometers or
thermistors, portable pH and conductivity meters, DO meters or optodes, optical
turbidity meters, fluorometers, etc.
Electrodes are small, low-weight sensors, which can be submerged in the water to be
monitored. The advantages are that they provide simple, rapid measurements with
high precision in a wide concentration range. Among their disadvantages are their low
sensitivity to the single parameter under investigation and malfunctioning arising
from clogging, coating, etc. Optical absorption and reflectivity spectrometers are also
available for a number of substances. Although these methods are simple, they are
limited in their concentration range with only medium sensitivity compared with
standard laboratory analysis. The biosensors are fast and efficient for measuring BOD
but are rather heavy. UV-absorption devices and fluorometers are often used to
measure dissolved organic load. These methods are simple, sensitive and rapid and
do not use chemicals. The biofluorometer uses the changes in fluorescence properties
of standard solutions, whereas other biosensors are based on the bioluminescence of
bacteria when exposed to toxic substances.
22 Guidebook
by Bartram and Ballance, 1996
32
Planning of water-quality monitoring systems
Partly owing to resource and time constraints to establish well-equipped WQ testing
laboratories in sufficient numbers and partly owing to the dynamic nature of WQ,
simplified WQ field test kits have been developed in an overall approach to WQM,
especially in developing countries. Kits can accomplish the initial screening and periodical
monitoring of waters. Such tests are relatively inexpensive and can be conducted at
water-user level, thereby improving the potential for involving user communities. Results
can be supported by detailed analysis of problem sources in proper laboratories.
There are field kits (discs, test strips, drop test kits, dipslides) that allow qualitative testing
for E-coli and bacterial contamination in general, DO, pH, electrical conductivity,
temperature difference, turbidity and level of nitrite, nitrate and orthophosphate ions,
arsenic, fluoride, iron, residual chlorine, chloride, alkalinity, hardness and aluminium.
The advantages of portable devices for field measurements are readily apparent. They
have the potential to reduce operator and analysis error when proper training and
operation are performed. The ability of a portable monitoring device to provide an
immediate result has application in isolated and developing areas where the safety of
drinking-water supplies is of paramount concern.
Automatic measurements
Recent years have seen a significant increase in automated measurements of physical
parameters, such as temperature, conductivity/salinity, pressure/depth, with other
measurements such as pH, turbidity, transparency and DO and colour-supplemented by
water-sampling for offline laboratory analysis. A significant driver for improved sensing of
inland waters is reduction of the labour costs involved in water-sampling, sensor
maintenance and servicing. Thus, sensors that require less frequent attention are a
priority requirement and are becoming more widely used.
In situ sensors play an integral role in the overall data-generation process, which is the
first link in the information-management system. They allow for the continuous or
intermittent collection of WQ parameter data in real- or near-real-time. High density of
measurements over relatively short periods can be critical because water-quality
conditions can vary widely, such as before, during and after storms. Sensors can be
cost-effective because they minimize costly field visits by scientists and technicians. The
monitoring devices may also include flow-through systems that enable rapid
measurements, either as continuous stationary measurements or used on a moving
platform (boat). In addition, real-time measurements for temperature, conductance and
turbidity can be correlated with other important water-quality properties, such as
bacteria, that are more costly and difficult to monitor and analyse. These new aspects
provide new possibilities for WQM.
It should be stressed, however, that the use of these special, multi-parametric, portable
instruments and automatic WQ stations still require regular – and sometimes
sophisticated and expensive – maintenance.
Box 6 lists available and reliable variables, suitable for incorporation into an automated
WQM programme.
Advances related to monitoring technology are needed to support future water-quality
issues successfully. They include, for example, continued development and testing of WQ
probes, monitors, data-recorders and telemetry equipment that allow the monitoring of
water-quality variables. Sensors can be cost-effective because they minimize costly field
visits by scientists and technicians. In addition, real-time measurements for temperature,
conductance and turbidity can be correlated with other important properties, such as
bacteria, that are more costly and difficult to monitor and analyse. Development, testing
and deployment of a new generation of real-time sensors for WQ have the potential
greatly to increase the level of information available at a given level of funding.
33
Chapter 7. Selection of water-quality monitoring methods and techniques
Box 6. Selected environmental variables that can be monitored automatically
Automatic measurements
Electronic
Temperature
x
Conductivity/salinity
x
Chlorophyll a
Optical
x
Cyanobacterial
x
pH
x
DO
x
x
Turbidity
x
Suspended solids
x
DOC
x
TOC
x
Nitrate
x
x
Nitrite
x
x
COD
Water level
x
x
Hydrocarbons
Water speed/direction
x
x
Environmental monitoring
Organisms living in aquatic environments are sensitive to changes, whether these be
man-made disruptions or natural environmental fluctuations. The reactions may be
subtle, in the form of reduced reproductive capacity and inhibition of specific enzymes
necessary for normal metabolism, or the reaction may be extreme, resulting in the
death of the organism or complete migration to another habitat. Unlike physical/
chemical analyses, which are conducted on water samples, biological indicators yield
cumulative information about both past and current situations. This is an ecosystem
approach to environmental monitoring, dealing with biological communities and not
simply a single, measured, WQ parameter.
Remote-sensing
The knowledge of the spatial distribution of different biological, chemical and physical
variables is essential in environmental water studies as well as for resource
management. Hence, coupled with advanced processing methods and improved
sensor capabilities, recent years have seen increasing interest and research in remotesensing of the quality of inland and coastal waters. Unless a water body is sufficiently
instrumented by in situ sensors, remote-sensing is the only satisfactory method to
detect the quality of remote and large inland waters. Thermal remote-sensing, for
example, can be used to define groundwater-discharge zones.
Remote-sensing technology provides an emerging capability that can significantly
augment or replace traditional in situ methods but the field is relatively new,
especially in addressing optically complex waters. Satellite-image archives exist,
dating back to 1970, enabling change detection of previously unmeasured or
unmonitored water bodies. Remote-sensing is a suitable technique for coarse-scale
monitoring of inland and coastal WQ. It provides a synoptic view of the spatial
distribution of different biological, chemical and physical variables of both the water
column and, if visible, the substrate.
34
Planning of water-quality monitoring systems
Advantages and shortcomings of the different monitoring methods
As a conclusion and to serve as guidance, the advantages and shortcomings of biological,
chemical and in situ WQM are summarized in Box 7.
Box 7. Biological, chemical and in situ WQM: advantages and shortcomings
Biological monitoring
Sampling for chemical
laboratory analysis
In situ sensors
Advantages
Good spatial and temporal
integration
Possibility of very fine
temporal variations
Relatively low cost
Good response to chronic, minor
pollution events
Possibility of precise pollutant Possibilities for continuous
determination
surveillance
Signal amplification
(bioaccumulation,
biomagnification)
Determination of pollutant
fluxes
Real-time studies
Real-time studies (in-line bioassays)
Measures the physical degradation
of the aquatic habitat
Valid for all water bodies,
including aquifers
Standardization possible
Valid for all water bodies,
including aquifers
Possibility of very fine
temporal variations and good
spatial coverage
General lack of temporal sensitivity
High detection limits for
many routine analyses
(micropollutants)
No precise pollutant or trace
element determination
Many semi-quantitative or
quantitative responses possible
No time-integration for water
grab samples
General precision lower
Standardization difficult
Possible sample
contamination for some
micropollutants (e.g. metals)
Advanced technology needed
Not valid for pollutant flux studies
High costs involved in
surveys
Not yet adapted to aquifers
Limited use for continuous
surveillance
Shortcomings
7.2 Frequency of sampling
The processes – natural and societal – that affect WQ have random features superimposed
on the hydrological, climatic and possibly other cyclic factors. The sampling schedule
should permit the adequate evaluation of the contribution of each of these factors to WQ at
a given location. The common approach in establishing the frequency of sampling is
statistical, based on the variability of the data, the concentrations to be measured and the
changes to be detected. In the absence of sufficient background data, an arbitrary
frequency is chosen, based on some knowledge of local conditions. After sufficient data
have been collected to evaluate the variability, the frequency is adjusted to reflect this.
Frequency is also influenced by the relative importance of the station and whether or not
the concentrations approach critical levels for some of the substances measured.
The frequency of sampling should be determined by balancing ecological needs with
economic possibilities. In the routine monitoring of a lake, the samples will usually be
taken several times during one year. The most important monitoring period is summer
stratification time. The primary production processes are then at their highest and the
decomposition of organic matter is most active. Especially in eutrophied or polluted lakes,
several samplings should be performed during the respective summer periods in the
northern and southern hemispheres.
Chapter 7. Selection of water-quality monitoring methods and techniques
35
Lakes exhibit a wide range of hydrological characteristics, from fast-flushing drainage
lakes to seepage lakes with a long residence time. Sampling frequency should be
designed to characterize the annual variability of lakes. Monthly samples are
recommended for most fast-flushing lakes, whilst more frequent sampling may be
required occasionally in lakes that undergo short-lived acidic episodes, algal blooming
or nitrate peaks. Also, where flow data are available for calculations of yearly
transport values of elements from catchments, increased sampling frequency in flood
periods is recommended.
Quarterly or seasonal sampling is likely to be adequate in lakes with long residence
times. In remote areas where frequent sampling is impossible for practical and
economical reasons, even one sample per year may be useful for long-term
monitoring. Such samples must be taken each year at the same time, usually at the
end of summer stratification, but in case of monitoring the acidification trend,
preferably shortly after autumn overturns.
Riverine fluxes of material are highly variable in time at a given sampling station.
Generally, TSS fluxes vary more than water discharge, while most major ion fluxes
vary less (owing to decreasing concentrations with increasing discharge).
Consequently, the optimum frequency for discrete sampling for flux determination is
influenced by these relationships. The optimum sampling frequency is the one above
which there is no significant gain in the accuracy of the flux determination with
respect to other errors involved (e.g. analytical error and errors arising from the
non-uniformity of the river section). For any given basin, the range of optimum
sampling frequency is affected by the basin relief and climatic influences; steep,
heterogeneous and dry basins need greater sampling frequencies than lowland,
homogeneous and humid basins of the same size. In small basins, more than four
samples a day may be necessary, whereas for large rivers such as the Amazon,
Mekong, Nile, Plata and Zaire, a single sample a month may be sufficient.
For groundwater, the sampling frequency is usually much lower – one to four times a
year – depending on the purpose of the monitoring. In specific cases, in aquifers with
high-flowing rates or in specific areas that are polluted or vulnerable to pollution, the
sampling frequency can become much higher.
The recommended annual sampling frequencies for stations in the GEMS/Water global
network are given in Table 8.
If the time of greatest variability or criticality of water quality is known, it may be
desirable either to increase the rate of sampling at such times or to divert a larger
proportion of the monitoring effort to those times. In rivers, such increased sampling
may be desirable during low-flow conditions in hot and dry seasons, or at times of
seasonal or other regular industrial and agricultural activities. Lakes are particularly
subject to regular periods of rapid change as a result of thermal stratification and
overturning. Aquifers may exhibit regular patterns of quality but rates of change are
relatively slow, except for highly permeable aquifers (see also Section 1.6).
7.3 Time of sampling
If, when cyclic variations occur, the samples are taken at constant intervals coinciding
with the period of the cycle and therefore at the same point on the cycle, the
successive results will be directly comparable for the purposes of assessing changes
in WQ. Such samples are not, however, representative in time and give no indication
of what is happening during the rest of the cycle.
The sampling programme may stipulate random sampling times but they should be
spread more or less evenly throughout the year. It is usually easier to organize the
36
Planning of water-quality monitoring systems
cyclic variations. For example, whatever time interval is decided, it could be based on
a multiple of 7 days + 1 day so that the sampling day advances or retreats throughout
the week. The samples may also roll through the 24 hours by using successive times
based on 24 + 1. Rolling programmes can lead to problems concerning rest days and
night work for both the sample collector and the analyst and some compromises may
be needed.
Chapter 8. Resources for a monitoring programme
The available national laboratory facilities, the inventory of field stations, equipment and
instruments, vehicles and transportation means and the office and field staff involved in
WQ activities, together with the financial means, constitute the main resources required
for a monitoring programme.
8.1 Laboratory facilities
Laboratory activities for WQ include concentration measurements and biological
determinations, which could also comprise the preparation of sample-collection devices
and sample containers, calibration of in situ meters prior to use in the field, quality-control
checks, collating data, etc.
Laboratories should be selected or set up to meet the objectives of each programme, with
attention being paid mainly to the choice of analytical methods. The range of
concentrations measured by the chosen methods must correspond to the concentrations
of the variable in a water body and to the concentrations set by any applicable WQ
standards.
During the initial stages of development of a national monitoring system, the focus should
be on the basic quality variables which, as a rule, do not require expensive, sophisticated
equipment. Gradually, the number of variables measured can be increased in relation to
the financial resources of the monitoring agency. The elaborate equipment and technical
skills necessary for the measurement of complex variables are not needed in every
laboratory.
In Bartram (1996) 23 a number of options are highlighted that may be available for
conducting analyses of water samples. The agency responsible for the monitoring
programme may have its own laboratory or laboratories, the facilities of another agency or
of a government ministry may be available or some or all of the analytical work may be
done under contract by a private laboratory. Some analytical work will inevitably be done
in the field, using either field kits or a mobile laboratory. Regardless of the options chosen,
the analytical services must be adequate for the volume of work expected and for the
quality of data required by the project’s data-quality objectives. Some of the relevant
considerations in this context are given below.
Variables to be analysed
If only a few simple tests are required, analyses can be undertaken in the field using field
kits. More complex testing programmes may require the services of specialized
laboratories.
Sampling frequency and number of sampling stations
The frequency with which samples must be taken and the number of sampling stations
involved will obviously influence the volume of work necessary and the staff and facilities
required.
23
The rest of this section is taken verbatim from Bartram (1996).
38
Planning of water-quality monitoring systems
Existing laboratory facilities
Laboratory facilities may be under the direct control of the monitoring agency or be
associated with another agency (e.g. the health ministry, a regional hospital or a
college or university). The major concern is that the laboratory is sufficiently close to
the sampling stations to permit samples to be delivered without undue delay.
On-site testing
Some analyses must be performed in the field. On-site monitoring instruments and
field-test kits are available that permit analyses of a wide range of variables. This
makes it possible to run a monitoring programme without the need for a fixed
laboratory but raises certain problems of analytical quality-control.
Temporary laboratories
If a monitoring programme is expected to be of short duration, it may be expedient to
set up a temporary laboratory. Sufficient space, water and electricity supplies are
essential but equipment and supplies can be brought in and then removed after the
monitoring programme is completed.
Mobile laboratories
It is possible to set up a laboratory in a suitable motor vehicle: truck, van, boat or even
an airplane. In effect, this is a variant of on-site testing, but may provide better
facilities than field kits.
In practice, the usual arrangement is for the agency responsible for WQM to establish
its own central laboratory, which can be organized to also provide training and
supervision of staff, equipment repair and various other services. If the monitoring
area is large or transportation is difficult, however, regional laboratories may be set
up or field kits used for certain analyses. Analyses that require expensive and
sophisticated equipment or that can be undertaken only by highly trained personnel
are performed solely at the central laboratory (e.g. analysis for heavy metals, using
atomic absorption spectrophotometry (AAS) and analysis for pesticides and
herbicides, using gas chromatography).
Whatever arrangements are finally chosen, it is essential that procedures are
established for quality-control of analytical work (described in Section 9.4). This is
important in all aspects of fieldwork, including sampling, sample handling and
transport, as well as on-site testing. Comparability of WQ data from different
laboratories can only be ensured if identical or, at least, similar methods are used or
through interlaboratory performance evaluation studies or proficiency testing in
accreditation schemes 24 .
There are many comprehensive standard manuals and guidebooks describing
laboratory methods in detail, such as Analytical Methods for Environmental Quality
(UNEP GEMS/Water, 2004). Their use helps to ensure the compatibility of data
supplied to national and global monitoring systems.
24
Bartram, 1996, 60-61
Chapter 8. Resources for a monitoring programme
8.2 39
Inventory of field stations, monitoring wells, equipment and instruments
A list of sampling sites (surface- and groundwater) will have been made and sampling
stations will have been chosen during the design of the monitoring programme. As indicated
in Section 5.2, an inventory of the sampling stations should be prepared that includes:
•
A map of the general area showing the location of the site and directions for getting
there;
•
A description of the sampling station or observation well and means of access, times
of day when samples are to be obtained, special equipment (e.g. ropes, lifebelts) and
clothing (e.g. waders) that are required when sampling at this station, tests that are to
be made on-site, travel time from the site to the nearest laboratory, etc.
There are numerous modern field instruments in many different price classes, which can
be used on-site for snapshot or continuous monitoring of several parameters (see also
Section 7.1 and Annex 2). The type of instrument relevant for the chosen programme
must be investigated.
Steps should be taken to ensure sufficient and stable financing, as well as the supply
of the stations with required spare parts or their replacement, the provision of up-todate equipment for laboratory devices, adequate means for sampling and sample
transport from remote stations. Adequate funding would also prevent departure of
qualified staff.
Plans to upgrade existing networks or to re-activate previously existing ones should be
based on a thorough analysis of the prevailing WQ situation and information needs, so
that informed decisions can be taken. There is also a need to set priorities which have
been agreed jointly with the major actors, both nationally and in the transboundary
context.
Regarding the sampling of groundwater, drilling holes to set up monitoring wells is
expensive. It is important to investigate the area and the presence of existing wells and
prepare a sound monitoring location plan so that future adjustments to the network are
avoided. If groundwater quality is measured at a spring, this should be effectively
protected, as the location cannot be changed.
8.3 Transport
The types of vehicle needed for field-sampling operations depend, to a large extent, on
the ease of access to the various sampling stations. If access is difficult, a four-wheel
drive vehicle may be necessary and, in some remote or rural areas, a light motorcycle
can be useful for transporting one person (with a minimum of equipment, e.g. portable
kit), although it is important to consider the safety aspects of the latter arrangement.
When measuring and sampling are carried out by a specialized team, it is desirable that
the means of transportation can also be used as a mobile “laboratory” for filtration, field
measurements and sample storage. When working in lakes and reservoirs, different
types of vessels, including small boats, may be used. Special ships with on-board
laboratories are only justified for large water bodies for which the travel time exceeds 48
hours and/or if systematic investigations of high intensity are required.
In countries or regions where reliable public transport is available, it may be possible to
arrange for samples to be transported to the laboratory by bus or train. Local agents,
appropriately trained and supplied with the necessary equipment, can take samples at
prescribed times and send them to the laboratory. This system requires careful
supervision and particular attention to sample quality-control.
40
Planning of water-quality monitoring systems
8.4 Staffing
Staff on a monitoring programme fall into four broad categories: programme
management, field staff, laboratory staff and data processors. The numbers required
in each category will depend on the size and scope of the programme and one person
may take part in several types of activity. In resource planning, it should be taken into
account that the need for qualified and experienced staff will place further demands
on the budget.
Programme manager
The manager will probably require the assistance of several technical and
administrative staff members during the design and planning phases of the
programme. Once the implementation stage has been reached, some of these can be
transferred to operations, possibly as supervisors of field and laboratory work.
Others, together with the programme manager, will assume responsibility for data
manipulation, preparation of reports, staff training and programme coordination (if
other agencies are involved in the programme).
The coordination tasks may become quite complex if programme implementation
depends on other agencies, part-time staff, temporary or rented facilities and public
transport. A possible description of the responsibilities of a programme manager is
presented In Table 9 as an example of what may be expected, although it may not be
complete for any specific situation.
Field staff
The personnel in charge of field measurements, sample collection and field handling
may not have had previous experience in WQM and must be specially trained for these
activities. The choice depends on a number of factors, which include the geographical
features of the region and the system of transportation. In large countries which have
a poor transportation system, relatively more personnel are required and more
automated systems are preferable. In this situation, specialists from
hydrometeorological and hydrological stations, for example, may be used, although
these personnel often do not possess the necessary training in water-sampling for
WQM.
For staff recruited for fieldwork and sampling, new observation and sampling methods
or procedures might need to be introduced from time to time. A short period of
training is, therefore, appropriate. Assuming that candidates have a good general
education, a well-organized training session that includes practical fieldwork will
require one to two weeks. If field testing is also to be carried out, the training period
will have to be somewhat longer. Staff should be evaluated after training and, if
satisfactory, should work under fairly close supervision until they are sufficiently
experienced to require this only on occasion. Periodic short-term training sessions
should be arranged for reviewing, reinforcing or extending knowledge. The
responsibilities of field staff are also shown in Table 9.
Laboratory staff
Two, or possibly three, categories of laboratory staff may be required to undertake the
required chemical, microbiological and biological analyses of the programme:
•
Laboratory chiefs : in liaison with the programme manager, the chiefs of each
type of laboratory would typically be responsible for laboratory management,
with tasks as given in Table 9;
Chapter 8. Resources for a monitoring programme
41
•
Laboratory technician (analyst) : laboratory technicians will usually have had
formal training and possibly practical experience in analytical work. Working
under the direction of the laboratory chief, a technician will be responsible for
preparing and carrying out analytical work in the laboratory. The technicians will
teach the assistants how to use laboratory equipment and carry out analyses;
and
•
Laboratory assistants : this category of staff might have had some formal training
but are usually untrained and often learn on the job. Their duties (see Table 9) are
performed under the direct supervision of the laboratory technician(s). In time,
and with appropriate training and experience, an assistant can be promoted to a
higher level of laboratory work. The assistants will use various items of
laboratory equipment, prepare reagent solutions and carry out certain analyses.
Quality assurance officer
It is considered good practice to designate a staff member as quality assurance officer
(QAO). Where financial/organizational constraints do not allow the appointment of a
specific QAO, the responsibility for QA may be delegated to a member of staff, in
addition to existing duties. QA is dealt with in more detail in Chapter 9.
8.5 Human-resources development and training
The quality of data produced by a programme depends on the quality of the work
done by field and laboratory staff. It is therefore important that staff are adequately
trained for the work to be done. As a result, monitoring agencies often develop
training programmes that are specific to their needs. Their content and extent depend
on the previous training and experience of staff, the range of activities involved in the
monitoring programme and whether analytical work will be done at a central
laboratory or regional laboratories and the extent to which analyses will be performed
in the field. These types of activity may also include capacity-building.
For large, permanent monitoring programmes, a comprehensive strategy for
personnel development is advisable. It should include:
•
Clear lines of responsibility and accountability;
•
Job descriptions;
•
Recruitment guidelines (qualifications, experience, skill requirements, etc.);
•
Career structures;
•
Mechanisms for enhancing the motivation of staff at all levels;
•
Systems for staff appraisal and feedback; and
•
Use of standardized training packages, procedure manuals and training manuals
as appropriate to the work of all staff (e.g. field and laboratory staff, regional and
national managers).
Training should be a continuing process: ideally, there should be a basic framework of
courses for staff at all levels, followed by short courses, seminars and workshops.
Supervision of work, in both the laboratory and the field, is essential and contributes
to in-service training. It is particularly valuable because it permits staff to gain
“hands-on” experience, thus reinforcing what was learned in formal training sessions.
42
Planning of water-quality monitoring systems
Training should be flexible, responding to experience and feedback and taking account
of the specific needs of individual staff members. In-house training can be readily
tailored to local requirements but needs staff familiar with the necessary training
techniques (usually senior laboratory and field staff – which also makes heavy
demands on them). Training may also generate significant demands on financial
resources and requires access to classrooms, fieldwork sites and training laboratories
with appropriate equipment. Many agencies will therefore make use of courses
already available at local education centres, supplementing these as needed with
short courses, workshops and refresher-training in specific topics.
In its broadest sense, training should also be understood to include encouraging staff
to join appropriate professional organizations, attend conferences and symposia and
communicate with peers in technical schools, colleges, universities and similar
establishments.
8.6 Communication
Good communication is important, not only for achieving programme outputs, but
also to ensure that wider aims (such as increasing awareness of environmental issues
and ensuring that staff of all types see their role positively) are met. It is also indirectly
important as a means of ensuring continued outside interest in, and support for, the
work being undertaken.
It is good practice to ensure that responsibilities for communication are identified in
staff job descriptions. Communication may be general, aimed at a wide audience, such
as writing reports or speaking at a seminar, or more specific, such as communicating
results from analyst to laboratory chief or the discussion of fieldwork plans between
coordinator and field staff.
Communication with external agencies is especially important if these play a role in
national or international assessments and if they provide other types of support (such
as training or equipment). For consistency, any liaison with such agencies should be
the specific responsibility of an identified member of staff. Internal communication in
the form of short discussions, such as lunch-time seminars or workshops, are a good
means of ensuring that staff are kept informed about issues and are aware of
programme progress and findings.
Representatives of monitoring programmes may attend committees at both local and
national levels. This representation is important as a means of communication, and
maintaining the profile of the programme should also be the specific responsibility of
an identified member of staff. Communication functions, such as those noted above,
may demand a significant proportion of time and this should be borne in mind when
preparing job descriptions.
8.7 Estimation of costs of the programme
The costs of monitoring should be estimated before programmes begin or when major
revisions are planned. If the information needs are well defined, the estimate can be
rather detailed. Monitoring costs can be divided into a number of components, as
shown in Box 8.
The costs associated with administration, as well as assessment and reporting, are
largely fixed and almost independent of the extent of the network. In contrast, the
costs of other activities are strongly influenced by the number and types of sampling
points, the frequency of sampling and the range of parameters to be analysed. The
Chapter 8. Resources for a monitoring programme
43
Box 8. Main water-quality programme cost components
• Network administration, including design and revision
• Capital costs of monitoring and sampling equipment, automatic measuring stations and datatransmission systems, construction of observation wells or surface-water-sampling sites and
gauging stations, transport equipment, data-processing hardware and software
• Labour and associated operating costs of:
– Sampling, field analysis of WQ variables and field measurements of water levels and discharge
characteristics
– Laboratory analyses
– Data storage and processing
• Operating costs of online data transmission systems (e.g. water levels, accidental water
pollution)
• Laboratory performance evaluations and proficiency testing
• Assessment and reporting: production of outputs, including GIS or presentation software and
report-printing costs
number of sampling points can be multiplied with frequency and parameters to obtain
rough cost estimates.
The most resource- and labour-intensive phase in monitoring is the one that includes
sampling, in situ physicochemical analysis and water-quantity-related measurements, and
laboratory analysis. This phase also entails high risks in producing reliable and accurate
data. It is therefore important to employ qualified and experienced personnel and comply
with guidelines and standards. It is also important to ensure that the supporting
infrastructure, such as reliable power and water supply, is in place.
It is important not to underestimate the labour and operating costs of sample collection
and field analysis, laboratory analysis and data processing, interpretation, reporting and
output production. A lack of knowledge or inadequate assessments of these costs may
lead to a cessation of activities, should sufficient funds be lacking.
The projected cost of what is considered to be the best proposal may often be too high for
the agency planning to carry out the monitoring. When faced with such a situation, some
of the possible solutions are a re-examination of:
•
Objectives of the programme, deleting some of the less important and/or relaxing
some of the conditions, e.g. changes to be detected;
•
Proposed sampling locations, eliminating some of the less important sites (e.g. those
at which WQ can be inferred from data already existing or from data collected at other
points in the system);
•
A proposed list of parameters to be analysed, deleting, for instance, those that can be
predicted from other measurements or that have a small or no environmental
significance at a given site; and
•
Frequency of sampling, especially when objectives of the monitoring have been
changed.
Programme funding
Because of the continuous character of monitoring, a long-term commitment to funding is
crucial to ensure the sustainability of monitoring and assessment activities. This means
that funding should come mainly from the national budget.
44
Planning of water-quality monitoring systems
Water users, such as municipalities, water and waste utilities, industries, farmers and
irrigation systems, should contribute to funding the programmes. Funds may also be
raised by using income from water-abstraction fees or by invoking the polluter-pays
principle.
Additional sources of funding might also be explored, a possibility being through
international assistance projects. These should be embedded in the national plans and
with system requirements adapted to countries’ needs, so that operations can continue
after a project is completed. Donor-funded projects concerning transboundary
watercourses and aquifers should be coordinated with national authorities to ensure the
continuity of monitoring activities that have been established in the project.
Chapter 9. Quality-assurance procedures
Quality assurance (QA) is a management method defined as “all those planned and
systematic actions needed to provide adequate confidence that a product, service or
result will satisfy given requirements for quality and be fit for use”. It is also defined as
“the sum total of the activities aimed at achieving that required standard” (International
Organization for Standardization (ISO), 1994).
Any monitoring programme or assessment must aim to produce information that is
accurate, reliable, comparable and adequate for the intended purpose. This means that a
clear idea of the type and specifications of the information sought must be known before
the project starts, i.e. there must be a data-quality objective. These objectives are
qualitative and quantitative specifications that are used to design the system that will
limit uncertainty to an acceptable level within the constraints allowed. They are often set
by the end-users of the data (usually those funding the project) in conjunction with the
technical experts concerned.
QA for a water-monitoring programme will, apart from helping to ensure that the results
obtained are correct, increase the confidence of funding bodies and the public. It extends
to all aspects of data collection from surveys to laboratory procedures. Unless the data
can be checked, they should not be included in any assessment; unconfirmed
observations have little value and can result in misclassification.
The purpose of this chapter is, therefore, to provide general guidance on the setting-up
of a quality system essential for ensuring the reliability of information obtained by
monitoring. It should be organized around all elements of the monitoring and
assessment cycle, starting with documenting procedures for the specification of
information needs and developing an information strategy. To assist this process, there
are standards, established under the auspices of ISO, the European Committee for
Standardization (CEN) and other organizations for sample collection, transport and
storage and laboratory analysis, as the basis for the quality system. Protocols for data
validation and storage and exchange, as well as data analysis and reporting, should be
established and documented.
It is essential to stress that the trend is to strengthen laboratory QA in a step-by-step
approach: from simple internal quality-control measures to laboratory accreditation and,
finally, to the application of international standards, such as ISO/IEC 17025, covering
general requirements for the competence of calibration and testing laboratories.
9.1 Components of quality assurance
These are often grouped under three levels:
•
Strategic or organizational level (dealing with quality policy, objectives and
management and usually produced as a quality manual);
•
Tactical or functional level (dealing with general practices such as training, facilities,
operation of QA); and
•
Operational level (dealing with the standard operating procedures (SOPs),
worksheets and other aspects of day-to-day operations).
46
Planning of water-quality monitoring systems
The quality manual is composed of a number of management documents needed to
implement the QA programme (ISO/IEC 17025, 2005), covering a whole range of areas
from quality policy statement to final procedures for audit and review. The list of
documents is provided in Table 10.
SOPs are the documents detailing all specific operations and methods, including sampling,
transportation, analysis, use and calibration of equipment, production of reports and
interpretation of data. They are the internal reference manual for the particular procedure
and should detail every relevant step. Anybody with the appropriate training level should
be able to follow the SOP.
Laboratories should use test methods which meet the needs of the customer and are
appropriate for the tests they undertake25. Method SOPs may have originated from a
number of organizations26 or from the instructions that come with the test kit when a
commercially produced method is used. Such SOPs have the advantage of not requiring
verification and save time in writing “in-house” SOPs. If they are applied, however, they
must be used without modification. Sometimes, in-house methods are preferred and it is
vital that they are appropriate for the intended use and fully validated. In order to maintain
the QA system, it is necessary to check periodically each area of the system for
compliance.
9.2 Laboratory facilities
It is essential that any laboratory facilities are adequately equipped to deal with the
analyses required and convenient for the delivery of samples. Small-scale organizations
responsible for monitoring may find it more convenient to use outside facilities for analysis
and sometimes for sampling. In these cases, the use of a laboratory belonging to an
accreditation scheme is advisable and, moreover, the laboratory should be inspected for
compliance by an experienced member of the monitoring programme. An inspection
should take into account the following features: (a) the lines of communication between
staff and management; (b) staff training and qualifications; (c) resources; (d) equipment
maintenance and calibration; (e) SOPs; (f) traceability of results; and (g) sample handling
and storage.
Where in-house facilities are used, it is essential that the monitoring work does not
overload the laboratory. Resources (staff, space, equipment and supplies) must be
sufficient for the planned workload. The laboratory must be well managed and conform to
all relevant health-and-safety guidelines. All analyses performed must be within the remit
and expertise of the facility and SOPs must be in operation for all analyses.
9.3 Equipment maintenance, calibration and quality-control of fieldwork
All equipment, whether field, office or laboratory, must be maintained on a regular basis as
documented in the relevant SOPs, codes of practice and manufacturers’ guidelines.
Laboratories must apply standards within the limits established for the care of a particular
piece of equipment: this applies to general equipment, as well as to sophisticated
analytical instruments and vehicles, and especially to field equipment. Equipment should
be checked for contamination, using blanks to ensure that it does not contribute to the
sample concentration or could be the source of cross-contamination between sampling
locations.
25
ISO/IEC 17025:2005, clause 5.4.2
26
For example: ISO, British Standards Institute, American Standard Technical Method
Chapter 9. Quality-assurance procedures
47
The care and cleaning of equipment are important to ensure analytical quality. Regular
internal and external calibration checks must be performed on equipment such as balances,
pipettes and all in situ sensors. The frequency of these checks depends on the stability of the
equipment in question but should be based on established practice and their form and
frequency should be documented in the relevant SOPs. Calibration and maintenance records
should be kept for all equipment, thus allowing the repair status to be monitored.
All automated sampling equipment must be calibrated and bench-tested prior to field
deployment. Calibration ensures that readings from instruments will be representative of
environmental conditions. Bench-testing provides the assurance that all components of
the system are functional. Each instrument will have a duty cycle that defines the period
between calibrations for which there should be confidence in the data. This cycle, which is
dependent on instrument type and deployment environment, must be determined for each
monitoring programme. For each instrument, a log of the calibration date and the next
calibration should be maintained and entered into the water-quality data-management
system. Each installation will also have a specific service cycle or the period between
required maintenance to be adhered to in order to maintain the functionality of the
instrumentation.
QA is critical in all fieldwork. If a good, practical, field QA programme is put into operation,
confidence in the data collected should be ensured (WHO/UNEP/VKI, 1997). Conditions in
the working area should not expose the operator to any undue risk. Standardized and
approved methodologies must be used at all times. If a method proves unworkable on-site,
then an alternative must be found and agreed by all involved. Operators must not change
procedures without referral to the management procedure. Where unavoidable changes
are made (e.g. in adverse weather conditions), they must be fully documented.
Nevertheless, a sampling plan should make provisions for such situations.
The quality of data generated in a laboratory depends primarily on the integrity and
representativeness of the samples that arrive at the laboratory. Consequently, the field
staff must take the necessary precautions to protect samples from contamination and
deterioration. In addition to standardized field procedures, field-quality control requires the
submission of blank and duplicate samples to: (a) test the purity of chemical preservatives;
(b) check for the contamination of sample containers, filter papers, filtering equipment or
any other equipment that is used in sample collection or handling; and (c) detect other
systematic and random errors occurring from the time of sampling to the time of analysis.
Replicate samples must also be collected to check the reproducibility of the sampling. The
timing and frequency of blank, duplicate and replicate samples are established in the
project design.
9.4 Analytical quality-control
This consists of two elements: internal quality control (IQC) and external quality control
(EQC). IQC consists of the operational techniques used by the laboratory staff for
continuous assessment of the quality of the results of individual analytical procedures.
EQC – or interlaboratory control – is carried out periodically and checked by the laboratory
responsible for the monitoring system. Whereas QA strives to achieve quality by
regulating procedures using management techniques, IQC focuses on the individual
method and tests its performance against mathematically derived quality criteria.
A summary of the IQC programme recommended by the GEMS/Water programme is
described in more detail in the GEMS/Water Operational Guide (WHO, 1992).
EQC is a way of establishing the accuracy of methods and procedures by comparing the results
of analyses made in one laboratory with the results obtained by others conducting the same
analyses on the same material. This is usually accomplished by one laboratory sending out sets
of samples, with known and unknown concentrations of variables, to all the specified
48
Planning of water-quality monitoring systems
laboratories. These analyse the samples for the specified variables and report the results to
the reference laboratory. The results from all participating laboratories are collated by the
organizers of the EQC programme and then subjected to detailed statistical analysis. A
report to each laboratory is generated, giving a target value for the reference sample or
samples (usually consensus mean or median), a histogram illustrating distribution of results
for each material and an individual performance score relating the individual laboratory
results to the target value. The calculations of performance indicators are often quite
complex because multiple specimens have to be considered and the method varies with the
concentration of the variable and its chemical status (i.e. Fe(III) or Fe(IV)). Nevertheless, the
general principle of providing a method of performance comparison remains the same in all
EQC exercises.
9.5 Quality assurance of data
Data QA is an important element of data analysis and use. While effective quality-control
procedures during sampling and analyses help to eliminate sources of error, a second
series of data checks and precautions should be carried out to identify any problems that
might lead to incorrect conclusions and costly mistakes in management or decisionmaking. The procedures involved commonly rely on the identification of outlying values
(values that fall outside the usual distribution) and procedures such as ensuring that data
fall within the limits of detection of a particular method of measurement.
QA should be applied at all stages of data gathering and subsequent handling. For the
collection of field data, design of field records must be such that sufficient necessary
information is recorded with as little effort as possible. Pre-printed record sheets requiring
minimal and simple entries are essential. Analytical results must be verified by the analysts
themselves checking, where appropriate, the calculations, data transfers and certain ratios or
ionic balances. Laboratory managers must further check the data before they allow them to
leave the laboratory. Checks at this level should include a visual screening and, if possible, a
comparison with historical values of the same sampling site. The detection of abnormal values
should lead to a further check of the analysis, related computations and data transcriptions.
The QA of data-storage procedures ensures that the transfer of field and laboratory data
and information to the storage system is done without introducing any errors. It also
ensures that all the information needed to identify the sample has been stored, together
with the relevant information about sample site, methods used, etc.
Data analysis and interpretation should be undertaken in the light of the results of any QA
checks. A data-storage and retrieval system must, therefore, provide access to the results
of these checks. This can be done in various ways, such as:
•
Accepting data into the system only if they conform to certain pre-established quality
standards;
•
Storing the QA results in an associated system; and
•
Storing the quality-control data together with the actual WQ data.
The choice of one of these methods depends on the extent of the QA programme and on
the objectives and magnitude of the data-collection programme itself.
9.6 WQ standards and indices
Monitoring and assessment of WQ is performed against existing standards and guidelines
that serve as reference and may predetermine which measures have to be undertaken to
Chapter 9. Quality-assurance procedures
49
improve WQ. In addition to many national standards are those of an internationally
recognized nature such as the WHO standard on drinking-water. Indices, such as measured
by aggregate parameters (BOD, COD, DOC and others) serve to characterize the overall
status of WQ that can then be documented in maps.
Typically, drinking-water quality is assessed by comparisons of samples to drinkingwater quality guidelines or standards. There is a distinction between these two terms.
The WHO Drinking-water Quality Guidelines provide international norms on WQ and
human health that are used as the basis for regulation and standard-setting in
developing and developed countries worldwide. They are adopted by countries as
national guidelines to follow, even if they are not necessarily enforceable by law. In
contrast, drinking-water quality standards are primarily set by nations and can be
enforceable by law. For example, the US Environmental Protection Agency has two sets
of standards: primary standards, that directly link human safety to drinking-water and are
enforceable by law; and secondary standards, that relate to aesthetic effects and are not
legally required.
Another example of binding standards is the EU Water Framework Directive (WFD), under
which drinking-water parameters are provided that include an obligation for EU countries
to inform the consumer on drinking-water quality and measures to be taken to comply
with the requirements of this Directive (see also Section 11.1). EU members have agreed
to comply with these parameters.
In addition, ISO publishes a series of approved International Standards, which includes
methods for determining WQ.
Appendix 1 provides a summary of international and national drinking-water quality
guidelines and standards by a number of international organizations (WHO, EU) and
selected countries27 (see also Section 6.2).
Many countries set drinking-water-quality guidelines based on the WHO guidelines but
may modify them, taking into account what is achievable in-country. For example, the
financial requirements and infrastructure needed to monitor and assess drinking-water
quality can be a constraint in some developing countries. For these and other reasons,
the guidelines may also vary between rural areas and urban centres within a country.
Composite indexes have also been developed to assess source WQ across a range of
inland water types, globally and over time. An example is the composite index developed
by GEMS/Water, with a three-fold approach: (a) selecting guidelines from WHO that are
appropriate in assessing global water quality for human health; (b) selecting variables
from GEMStat that have an appropriate guideline and reasonable global coverage; and
(c) determining, on an annual basis, an overall index rating for each station, using the
WQ index equation endorsed by the Canadian Council of Ministers of the Environment.
The index allows measurements of the frequency and extent to which variables exceed
their respective WHO guidelines at each individual monitoring station included within
GEMStat, allowing both spatial and temporal assessment of global water quality.
Important criteria for selecting indicators include:
•
Communication: indicators should be suitable for all users;
•
Simplification: indicators should provide insight, without giving too much
unnecessary detail; and
•
Availability of data: enough data must be available to formulate reliable indicators.
27
Australia, Canada, Japan, New Zealand and USA
50
Planning of water-quality monitoring systems
The Indicators for Sustainable Development devised by the United Nations (UN, 2001) and
the list of indicators in the EEA’s Environmental Signals 2001 (EEA, 2001) report are of
great assistance in selecting suitable indicators.
Finally, efforts are now being made to develop and apply indicators of WQ stress and
long-term change. Indicators can be used to relate WQ to environmental stressors
(e.g. expanding population, climate change, industrialization and sanitation).
Chapter 10. Data management and product development
Data produced by monitoring programmes should be validated, archived and made
accessible. The goal of data management is to convert data into information that will
meet needs and the associated monitoring objectives. The combined use of data from
multiple sources places high demands on data exchange and data-management systems.
To safeguard the productive future use of the data collected, four data-management
steps are required before the information can be properly used:
•
Data should be analysed, interpreted and converted into defined forms of
information, using the appropriate data-analysis techniques;
•
Data should be validated or approved before they are made accessible to users or
archived;
•
Information should be reported to users for decision-making, management
evaluation or in-depth investigation. Information should also be made accessible to
the public and presented in tailor-made formats for different target groups;
•
Data needed for future use should be stored and the exchange of data should be
facilitated at all other appropriate levels (international, regional, river basin, etc.), as
well as within the monitoring body itself.
It is of utmost importance that policymakers and planners are fully aware of the various
steps in data management. This will facilitate data exchange among the institutions
undertaking the monitoring and assessment, including joint bodies. The purpose of this
chapter is therefore to provide general guidance on each of the above four datamanagement steps to allow a proper use of the information obtained by monitoring.
10.1 Data handling and management
The first archiving of monitoring data generally takes place at the monitoring agency. To
facilitate the comparability of data, clear and precise agreements should be made on the
coding of data and meta-information. Standardized software packages for data
management should be applied where data are to be stored, with storage formats used
to allow for data exchange. Framework agreements regarding the availability and
distribution of data can further facilitate their exchange. The relevant data terminology
should be jointly compiled and agreed, including definitions of terms used during the
exchange of information or data.
Furthermore, a sufficient amount of the secondary data – metadata – needed to interpret
the data should also be stored. Details of the times and places of sampling, the type of
sample and any preconditioning and analytical techniques used are commonly stored for
these purposes. If monitoring is performed in any media other than water (e.g. in
suspended solids or biota), relevant metadata such as the total amounts of substances in
different media and particle size distributions should be recorded.
GIS are important tools for the integrated interpretation of data, together with any other
information (e.g. maps, satellite images, land-use data, etc.) that may be needed to
assess water quality and quantity or, in the event of accidental pollution, flooding, etc.
52
Planning of water-quality monitoring systems
This allows models to be used with controlled access to the system given to a range of
information users and reports adapted to suit the recipients.
Over the past few years, GIS technology has also been increasingly used for
groundwater-quality data collection.
The data needed for purposes such as the assessment of the ecological state of a water
body or for load calculations are often produced by separate monitoring programmes
run by various laboratories or agencies. Data from other sources are often indispensable
for assessment purposes, in addition to the monitoring data. Special attention should be
paid to the validation and quality-control of the process of data collection from these
multiple sources. Steps should also be taken to ensure interoperability of the WQ data
from different observation platforms and networks.
Databases should be suitably harmonized. Standardized interfaces should be used to
interconnect databases and provide for integration with a GIS. Relational databases
should preferably be used to facilitate integration with GIS and models. Data processing
based on jointly accepted, compatible standards will make assessment and reporting
comparable, even when the software used in the various countries differs.
The scope and nature of computerized data-handling processes will be dictated by the
objectives of the WQM programme. However, a database offers the best means of
handling large quantities of data and should be capable of exporting data in formats that
are accepted by all good statistical, spreadsheet and GIS packages.
Designing a WQ data-storage system needs careful consideration to ensure that all the
relevant information is stored such that it maintains data accuracy and allows easy
access, retrieval and manipulation of data. While it is difficult to recommend one single
system to serve all agencies carrying out WQ studies, some general principles may serve
as a framework for designing and implementing effective WQ data-storage and retrieval
systems which will serve the particular needs of each agency or country.
For international data-storage purposes, a central system may be considered. This task
could be given to joint bodies, including representatives of the national authorities of the
riparian countries concerned. Guidelines and tools developed within the framework of,
for example, the common Water Information System for Europe (WISE) 28, supports such
activities.
10.2 Data analysis and dissemination
In monitoring programmes where large amounts of different data are collected
continuously over several years, statistical methods are needed to summarize effectively
the results of monitoring. In particular, different types of trend calculations are being
used to assess monitoring data. In interpreting trends, particular attention should be
paid to water-quantity data, since hydrology strongly affects WQ. It is also necessary to
be able to give some indication of the “confidence” the user may have in the statistical
outputs.
Data analysis should be embedded in a data analysis protocol (DAP) that clearly defines
an analysis strategy, taking into account the specific characteristics of the data
concerned, such as missing data, detection limits, censored data and outliers,
non-normality and serial correlation. The adoption of a DAP gives the data-gathering
agency a certain flexibility in its data analysis but requires that the procedures be
documented.
28
http://water.europa.eu
Chapter 10. Data management and product development
53
Production and display of graphical material can be made in several ways, depending on
the analysis underway. Typically, XY, scatter time-series and regression plots are
desirable for displaying data to identify preliminary WQ conditions. Graphs can reveal
patterns in sets of data and are often more illustrative than statistical computations. By
using the tailor-made software, graphical output can be included in map format. This
type of presentation is useful for producing reports on environmental conditions.
Groupings of stations within a watershed, nation or region can be accomplished by
retrieving and aggregating data.
Statistical tests, including regression analysis, can be used for both data-quality scans
and trend identification. Long-term changes relative to specific criteria can provide
indications of emerging environmental issues that could be addressed prior to largerscale difficulties in water usage presenting themselves. In investigating long-term
changes in river WQ, time-series analyses of instantaneous discharge records in
combination with one or more specific parameters can easily depict dependent and/or
independent relationships. Data summaries in the form of statistical tables can provide
the necessary information for many components of environmental assessments.
The use of water-classification systems to assess watercourses is common. Some of
these are based on physical-chemical variables, but biological approaches (such as
ecological classification under the WFD) are also used. For transboundary water
assessments, whether based on classification systems or on other assessment methods,
it is important to strive for comparability of results rather than unification of methods.
WQ issues are basically site-specific, but local actions and regional activities can greatly
benefit from linkages at the global level, such as: (a) sharing experiences between sites
and regions; (b) exchanging data and information on global scientific and Internet
developments; and (c) situating WQ data within a broader geo-spatial context for
analysis and assessment. Data exchange is important in WQ studies. Data-exchange
protocols exist for national and international purposes, one useful example being the
WMO policy on the exchange of hydrological data and products (Resolution 25 (Cg-XIII) –
Exchange of hydrological data and products).
Many policy- and decision-makers at local, national and regional levels are concerned
about investing adequately in data-collection systems. Many governments around the
world are becoming increasingly interested in developing national data and information
systems, as well as in ensuring their interoperability. This refers to the ability of a
database or system to exchange information and to use the information that has been
exchanged. This is often achieved using open Web services.
Unfortunately, long-term monitoring records are rare because of the lack of resources
available to sustain them, but they are extremely valuable when available. The GEMS/
Water Programme collects WQ data on a global scale and maintains an online database
(GEMStat) with almost four million entries covering the period 1965-2009 (www.gemstat.
org, see also Section 11.2). GEMStat provides environmental WQ data and information
with high integrity, accessibility and interoperability. These data serve to strengthen the
scientific basis for global and regional water assessments, indicators and early warnings.
The success of the database depends on the important role that participating countries
play in regional and global water-information systems, to ensure the widest coverage
possible and, consequently, the ability to share data and information. The International
Groundwater Resources Assessment Centre (IGRAC, www.igrac.net) currently provides
information on groundwater quality on a global scale on fluoride, arsenic and salinity.
Additionally, a database on guidelines and protocols for groundwater data acquisition
with about 400 documents is available via the Internet 29.
29
http://www.igrac.net/publications/128
54
Planning of water-quality monitoring systems
10.3 Reporting
This is the final step in the processing of information and links the process to the
information users. The main issue is to present the interpreted data in an accessible way.
How this information is to be presented depends greatly on the audience to be addressed.
The several different types of reports that are possible have certain elements in common,
including the statement of objectives and the description of the study area. To avoid any
misunderstandings, it is important that all elements of the monitoring programme are
precisely and clearly described. There are four principal types of reports:
•
The study plan report defines the objectives of the monitoring programme, including
the questions to be addressed and the present understanding of the environment to
be studied. It also defines the sampling and data review strategy that will be followed
to meet the objectives;
•
The protocol and methods report, also defined as the SOP, describes methods and
equipment in sufficient detail for other scientists to be able to assess the scientific
validity of the results reported;
•
The data report, whose primary purpose is to transmit information assembled in a
well-organized format so that the reader can easily review it; and
•
The interpretative report, which provides a synthesis of the data and recommends
future actions. Interpretative reports should be produced regularly to ensure that
programme objectives are being met and are currently valid.
In general, reports should be prepared on a regular basis. They need not necessarily be
printed but can take other forms, such as oral reports or digital presentations. Their
content, which may involve transferring data analyses or merely give a brief overview of
conclusions and frequency and level of detail, will depend on how the information is to be
used. Technical staff will need reports more frequently than policymakers, for instance.
Reporting has to be tailored to meet the needs of those who request the information.
Public authorities, including joint bodies, usually request information in a formalized
manner. In such cases, the content and frequency of reports are defined in reporting
protocols. Such reports are usually presented in writing to ensure that results are clearly
understood.
National authorities may also receive ad hoc requests (e.g. from individuals, environmental
groups or organizations) for information which is not routinely included in reporting
protocols, but which may be related to specific, current water-management issues. Raising
the awareness of progress in water management will increase governmental and public
support for governmental interventions.
Quality status reports or environmental indicator reports should provide concise
information to support decision-making in water management. These reports typically
provide information on the functions of water bodies, describe problems and the pressures
to which they lead and give insight into the intended impacts of corrective measures. They
are much more useful for decision-making purposes where simplifying indicators and
visuals are used.
Standardization of reports is encouraged within river basins and at the international level.
Joint river-basin quality status reports should preferably be produced. National and
international reporting obligations should be inventoried to ensure all reporting
requirements laid down in water-management legislation are fulfilled. For example, the
EEA’s Reporting Obligations Database includes an overview of many international
reporting obligations. This database may be complemented with reporting obligations
under national, bilateral or multilateral legislation.
Chapter 11. International water-quality directives and guidance
material
Multilateral environmental agreements, international conventions and transboundary
water agreements contain obligations for countries to monitor, assess and report on the
water-quality status of their watercourses and groundwater. Coupled with international
guidance material on the subject, these should assist in steering and guiding related
national activities.
11.1 International frameworks
Multinational environmental agreements, conventions and protocols, directives and
bilateral and multilateral transboundary water agreements contain obligations for
countries to monitor and assess watercourses and groundwater and to report, as
appropriate, to a specific body, such as an international commission, secretariat or
organization. Such cooperative arrangements and institutional frameworks greatly
influence the efficiency of monitoring and assessment and help in the planning phase of
the monitoring network. Ideally, these obligations should become part of the national
legislation to steer the activities of competent national bodies. Regional, national and
international legislation and policies can determine the main objectives for WQ
assessments. In some countries, WQ standards or guidelines may be laid down by national
legislation. It is, however, not realistic to expect all countries to amend their national
legislation in the short term. A few examples are described below.
The EU WFD legislation and Infrastructure for Spatial Information in the European
Community (INSPIRE, http://inspire.jrc.ec.europa.eu/) provide a major tool for defining
how European waters should be used, protected and restored. EU Member States are
solely responsible for the implementation of the requirements set in water-related
directives. The most important where monitoring is concerned is the WFD. Its main aims
are to prevent further deterioration in aquatic ecosystems, while protecting and enhancing
their status, to promote sustainable water use and to mitigate the effects of floods and
droughts. The environmental objective of the WFD is to ensure that the ecological and
chemical status of all waters within the EU is at least good by 2015 at the latest. The
programme is based both on the use of hydrobiological characteristics, supported with
some key physicochemical variables, and on surveillance of certain harmful substances,
including priority substances. The WFD also takes into account hydrological variations
during the monitoring period.
The Groundwater Daughter Directive (GWD)30 to WFD establishes specific measures as
provided for in Article 17(1) and (2) of Directive 2000/60/EC in order to prevent and control
groundwater pollution. These measures include, in particular: (a) criteria for the
assessment of good groundwater chemical status; and (b) criteria for the identification and
reversal of significant and sustained upward trends and for the definition of starting points
for trend reversals. The GWD also complements the provisions preventing or limiting
inputs of pollutants into groundwater, already contained in Directive 2000/60/EC, and aims
to prevent the deterioration of the status of all bodies of groundwater. For some
groundwater-quality assessments, specific threshold values or standards exist for the
different objectives (Blum et al., 2009). A description of different methodological aspects
of trend analysis in relation to the GWD can be found in Broers at al., 2009.
30
http://rod.eionet.europa.eu/instruments/625
56
Planning of water-quality monitoring systems
Finally, the Nitrates Directive31 (91/676/EEC) has the objective of reducing water pollution
caused or induced by nitrates from agricultural sources.
The INSPIRE Directive (May 2007) establishes an infrastructure for spatial information in
the European Community to support environmental policies and policies or activities
which may have an impact on the environment. It addresses 34 spatial data themes
needed for environmental applications, with key components specified through technical
implementing rules.
As regards transboundary waters and international lakes, one essential basis for the
required monitoring and assessment activities is the 1992 UNECE Convention on the
Protection and Use of Transboundary Watercourses and International Lakes (Water
Convention). The Convention aims to establish effective systems for monitoring and
assessing situations likely to result in outbreaks or incidents of water-related disease,
along with suitable response-and-prevention procedures. This will include inventories of
pollution sources, high-risk area surveys regarding microbiological contamination and
toxic substances, and reporting on water-related diseases. Parties to the Protocol on Water
and Health will also develop integrated information systems covering long-term trends in
water and health, focusing on both current concerns and past problems and their
successful solutions, whilst ensuring that such information is provided to the relevant
authorities. Moreover, comprehensive national and local early warning systems are to be
established, improved or maintained. In January 2009, a resolution was adopted by the
United Nations on the law of transboundary aquifers32, recommending States to make
appropriate bilateral or regional arrangements for the proper management of their
transboundary aquifers on the basis of the principles enunciated in the articles (Resolution
A/RES/63/124).
Outside Europe, a large number of new bilateral and multilateral water agreements33,
governing basins in Asia, Africa, the Middle East and North and South America were
concluded during the 1990s. Provisions concerning information exchange, monitoring and
evaluation are included in many treaties and a growing percentage of agreements address
some aspect of WQ management in international rivers. Some significant examples are the
Mekong River Initiative, the Nile Basin Initiative and the Zambezi Water Agreement. The
International Joint Commission has been implementing the Boundary Waters Treaty in
North America since 1909.
11.2 Global databases
Monitoring and assessment activities under the auspices of UN organizations and
programmes produce valuable information which can be used for carrying out
assessments of national and transboundary watercourses and groundwater. The UNEP
GEMS/Water Programme is a primary source of global WQ data and provides information
on the state and trends of regional and global water quality. GEMS/Water receives WQ
data derived from national focal points in participating countries from their ongoing
national monitoring programmes and from collaborating focal points at universities,
international partner agencies and organizations such as transboundary water-basin
authorities. These data are housed in GEMStat, a global database with almost four million
WQ data from lakes, rivers and groundwater in more than 100 countries. Information on
aquifers can be obtained from the International Shared Aquifer Resources Management
programme, which aims to develop methods and techniques for improving understanding
of the management of shared groundwater systems, taking into consideration both
31
32
33
http://ec.europa.eu/environment/water/water-nitrates/directiv.html?lang=_e
In the Netherlands, there is at least one case of sampling at the border to prevent inflow of contaminated
groundwater.
http://www.waterencyclopedia.com/St-Ts/Transboundary-Water-Treaties.html#ixzz0VueDqySO
Chapter 11. International water-quality directives and guidance material
57
technical and institutional aspects. IGRAC, which facilitates and promotes the worldwide
exchange of groundwater knowledge to improve assessment, development and
management of groundwater resources, is another important source of information.
Regarding groundwater quality, IGRAC’s focus relates to fluoride, arsenic in groundwater
and saline groundwater. The Global Groundwater Monitoring Network (GGMN) aims to
collect aggregated groundwater-quantity and quality data to assess the status of
groundwater worldwide.
The Statistical Office of the European Commission (Eurostat) collects statistics on water
resources, water abstraction and use and wastewater treatment and discharges through
the Eurostat/OECD joint questionnaire. One important source of information on the status
of rivers, lakes and groundwater bodies is WISE, created by the EEA. It is being further
developed to comply with the recommendations on the strengthening of national and
transboundary environmental monitoring and information systems in countries of eastern
Europe, the Caucasus and Central Asia.
The National Meteorological and Hydrological Services of Members of WMO operate more
than 475 000 hydrological stations worldwide. National databases are good sources of
water-quantity data and related information. WMO’s GRDC is a worldwide, digital
depository of discharge data and associated metadata and serves as a facilitator between
data providers and data users.
Data on water-related disease can be accessed through the Health for All Database of
WHO. This database includes data on diarrhoeal diseases, viral hepatitis A and malaria
incidence, as well as the number of people being connected to water-supply systems and
having access to sewerage systems, septic tanks or other hygienic sewage-disposal
systems. Supporting data are available from the Joint Monitoring Programme (JMP),
carried out under the auspices of WHO and the United Nation’s International Children’s
Fund (UNICEF). The goal of JMP is to report on the status of water supply and sanitation in
the context of meeting the UN Millennium Development Goals.
11.3 Related guidance material
A wealth of experience has been accumulated and is available through a number of other
guidebooks and reports on the basic methods, procedures, techniques, field equipment
and analytical instruments, etc. required to monitor water quality and quantity. Their use in
conjunction with the present Technical Report is therefore strongly recommended. A
summarized description of relevant guidance material34 in various related fields that may
be consulted as required for the various planning steps follows.
UNEP GEMS/Water aims to improve the understanding of emerging WQ issues around the
world, its main goals being monitoring, assessment and capacity-building. The
implementation of GEMS/Water involves several UN agencies active in the water sector, as
well as various authorities, institutions and organizations. GEMS/Water has based its
monitoring operations on a practical guidebook, the GEMS/Water Operational Guide
(GEMS/Water, 1992/2004) which provides detailed information on site selection, sampling,
analysis, quality control and data processing.
There are many comprehensive standard manuals and guidebooks describing laboratory
methods in detail, such as the GEMS/Water Analytical Methods for Environmental Quality
(UNEP GEMS/Water, 2004). Their use helps to ensure the compatibility of data supplied to
national and global monitoring systems.
34
As appropriate, reference has been made to this material throughout the text of this Technical Report.
58
Planning of water-quality monitoring systems
Although analytical reference methods are given in several general publications, it is also
convenient to consult the ISO Standard Methods series of publications and the WHO Water
Quality Guidelines and to refer to recognized national publications, such as the standard
methods produced by the American Public Health Association (APHA, 1989), the German
Institute for Standardization35 (DIN) and those of the former USSR State Committee for
Hydrometeorology and Environmental Control (1987, 1989) which are now used in the
Russian Federation and other countries of the Commonwealth of Independent States.
It should be noted, however, that, while most chemical analyses required for WQM are
adequately covered in the above reference guidance material, non-standardized methods
for biological monitoring have to be developed for local or regional situations.
Hydrological measurements are an indispensable accompaniment to any surface WQM
operation. Groundwater-quality data also require adequate hydrological information for
any meaningful interpretation. WMO has developed practical guidelines for hydrological
practices (WMO, 1994) and the United Nations Educational, Scientific and Cultural
Organization (UNESCO) has also issued groundwater hydrology guidebooks. These
publications contain methodology for WQ data collection, interpretation and presentation.
With respect to the field operations for WQM, a practical manual was produced by WMO
(WMO, 1988), of which several main items are still valid. It describes essential factors to
consider in monitoring, for example: the location of sampling sites, the collection of
surface-water samples, field measurements, sampling for biological analysis, shipment of
samples, field safety and training programmes related to all of the above.
IGRAC has developed a database on guidelines and protocols for groundwater data
acquisition with about 400 documents.
35
DIN 38414-11, August 1987: German standard methods for the examination of water, wastewater and sludge;
sludge and sediments (group S); sampling of sediments (S 11).
Chapter 12. Summary and future needs in water-quality monitoring
Despite some progress over the last 15 years, inadequate freshwater supplies and the lack
of sanitary wastewater systems continue to plague vast regions and populations of the
planet. Approximately 1.1 billion people lack access to clean drinking-water, while
2.6 billion people suffer from inadequate sanitation. As a result, diarrhoeal diseases
associated with tainted water and inadequate sanitation kill 1.8 million people annually –
mostly children.
Building the capacity of communities, local, regional and national governments, NGOs and
enterprises to manage and deliver water and sanitation services are key challenges in
meeting the UN Millennium Development Goals for water.
While capacity-building encompasses financial, educational and social goals, there is also
a technological element, in which WQM and analysis equipment must be deployed on an
increasingly wide scale in developing countries where water supply and wastewater
treatment are inadequate.
In addition to many of the ongoing problems associated with WQ that have as yet not been
solved, the world is also facing new environmental problems that threaten aquatic and
terrestrial ecosystems. Climate variability, biotic invasions and the introduction of new
chemicals and microbes to water bodies continuously pose new threats to aquatic
ecosystem health that must be addressed by regulatory authorities on local, national and
global scales (Water Quality Outlook, GEMS/Water, 2007).
Changes in average temperature, precipitation levels and rising sea level are expected to
occur over the coming decades, partially in response to changes in atmospheric circulation
indices such as the El Niño Southern Oscillation and North Atlantic Oscillation. These are
likely to influence both the quantity and quality of inland waters (rivers, lakes, reservoirs
and groundwater). Long-term monitoring records for lakes and reservoirs worldwide show
increases in temperature over the last three decades. The success of local, regional and
global efforts to curb rates of WQ degradation can only be measured if sufficient data are
available to track trends over time and space. New approaches and techniques need to be
developed and applied to address emerging issues and to provide decision-makers with
relevant and accurate assessment data and information.36
WQ issues in developed countries have increased in complexity as a result of the move
from point-source controls, focusing on “end-of-pipe” site-specific data, to investments in
WQ protection and enhancement, focusing on non-point-source pollution and a wholewatershed approach. Eight priorities have been identified to meet future needs for WQM
and assessment (see Box 9). A commitment to these priorities will provide the critical
scientific basis for the multitude of decisions involving the increasing number of
competing demands for safe drinking-water, irrigation, industry, aquatic ecosystem health,
wetland protection, the preservation of native and endangered species, and recreation.
In addition to the importance of being able to access existing WQ data sources, new
technologies for WQM that are rapid, quantitative, field-deployable, comprehensive, simple
to use and cost-effective are needed to increase the availability of worldwide WQ data.
Currently, data gaps exist in many regions without national WQM programmes, while
existing surveys do not necessarily provide essential quantitative information on source or
end-user WQ. Furthermore, the need for new WQ assessment tools is not limited to
developing countries.
36
GEMS/Water 2007.
60
Planning of water-quality monitoring systems
Box 9. Priorities to meet future needs for WQM and assessment37
Page
• Understanding the relations between WQ conditions and the natural landscape, hydrological
processes, the subsurface and the human activities that take place on the landscape within
watersheds
• Assessing WQ in a “total resource” context
• Evaluating WQ in concert with water quantity
• Evaluating WQ in concert with biological systems
• Monitoring over long timescales, taking care to place measurements in a historical, hydrological
context
• Early warning of accidental pollution
• Moving from monitoring to prediction and applying the understanding of the hydrological
system and water-quality conditions to non-monitored, yet comparable areas
• Investing resources to gather ancillary information on landscape and human factors controlling
WQ
• Advancing monitoring technology, such as that for measuring WQ in real-time
Current WQM information and assessment are based mainly on in situ data. One exciting
future prospect is that such assessments can benefit from other sources of data,
particularly space-based observations, in a reliable and operational manner. Linking the
two sources of data would be a valuable scientific resource because of potentially
extending the scope, scale and replicability of data gathering for assessment purposes, as
well as of developing new models and methodologies.37
In conclusion, the important results to be expected of successful WQM programmes may
be summarized as follows:
•
Identification of management and policy information needs;
•
Linkage to institutional arrangements with regulatory ability (i.e. to establish
standards);
•
Improved coordination among the organizations involved in water, sanitation and
ecosystems and human health;
•
Definition of data and information needs and the subsequent design of the monitoring
network to meet them;
•
Reliable and timely data collection and reporting;
•
Co-location of WQ and quantity stations for the calculation of fluxes;
•
An adequate number of monitoring stations strategically located to have accurate and
reliable country/basin coverage, i.e. stations at headwaters and where a river enters
the marine environment or a large inland groundwater body or crosses an
international border;
•
Response to unexpected problems and emerging issues;
•
Addressing country needs by building capacity and empowerment;
37
3Source: Hirsch et.al., 2006
Chapter 12. Summary and future needs in water-quality monitoring
•
Strengthening existing network infrastructure and institutions rather than creating
new ones;
•
Promotion of free access to information through the interoperability and
comparability of methods; and
•
Systems kept up to date (IT, analytical etc.).38
61
All this should lead to providing the needed basis for decision-makers effectively to allow
the management and protection of water resources across nations and in specific
geographical areas, now and in the future.
38
GEMS/Water 2005.
Tables
Table 1. Categories and principal characteristics of water-quality monitoring operations
Type of
operation
Multi-purpose
monitoring
Station
density and
location
Sampling or
observation
frequencies
Number of
variables
considered
Duration
Interpretation
lag
Medium
Medium
(12 per year)
Medium
Medium
(> 5 years)
Medium
(1 year)
Other common water-quality operations
Low for single
objective; high
for multiple
objective
> 10 years
> 1 year
High
Depending on
media
considered
Medium to high
Once per
year
to once every
4 years
1 year
Low: at
specific uses
Medium
Specific
Variable
Short
(month/week)
Low: major
uses and
international
stations
Very high
Basic survey
Operational
surveillance
Trend
monitoring
Specific water-quality operations
Background
monitoring
Low
Low
Low to high
Variable
Medium
Preliminary
surveys
High
Usually low
Low to medium
(depending on
objectives)
Short < 1
year
Short (months)
Emergency
surveys
Medium to
high
High
Pollutant
inventory
Very short
(days-weeks)
Very short
(days)
Limited
downstream
pollution
sources
Medium
Specific
Variable
Short to
medium
Short
Instantaneous
Impact
surveys
Modelling
surveys
Specific
(e.g. profiles)
Specific (e.g.
diel cycles)
Specific
(e.g. DO, BOD)
Short to
medium, two
periods:
calibration
and
validation
Early warning
surveillance
Very limited
Continuous
Very limited
Unlimited
Source: D. Chapman (Ed.), 1996
The levels (high, medium, low) of all operation characteristics (frequency, density, number of variables,
duration and interpretation lag) are given in relation to multi-purpose monitoring, which has been taken as a
reference. Important monitoring characteristics are emphasized in bold.
63
Tables
Table 2. GEMS/Water variables
General water quality
Organic matter
Particulate matter
Water discharge/level
Total suspended
solids (R)
Temperature
pH
Electrical conductivity
DO
Transparency (L)
Organic carbon, dissolved
Organic carbon, particulate
BOD
COD
Chlorophyll a (R,L)
Aluminium, particulate (GRF)
Arsenic, particulate (GRF)
Cadmium, particulate (GRF)
Chromium, particulate (GRF)
Copper, particulate (GRF)
Iron, particulate (GRF)
Lead, particulate (GRF)
Manganese, particulate (GRF)
Mercury, particulate (GRF)
Selenium, particulate (GRF)
Zinc, particulate (GRF)
Dissolved salts
Calcium
Magnesium
Sodium
Potassium
Chloride
Fluoride (GW)
Sulphate
Alkalinity
Ionic balance
Sum of cations
Sum of anions
Sodium adsorption ratio
Nutrients
Nitrate plus nitrite
Ammonia
Organic nitrogen, dissolved
Organic nitrogen, particulate
Total phosphorus, dissolved
(R,L)
Total phosphorus, particulate
Total phosphorus, unfiltered
(R,L)
Silica reactive (R,L)
Microbial pollution
Faecal coliforms
Total coliforms
Inorganic contaminants
Aluminium, dissolved
Aluminium, total
Arsenic, dissolved
Arsenic, total
Boron, dissolved
Boron, total
Cadmium, dissolved
Cadmium, total
Chromium, dissolved
Chromium, total
Copper, dissolved Copper, total
Iron, dissolved
Iron, total
Lead, dissolved Lead, total
Manganese, dissolved
Manganese, total
Mercury, dissolved
Mercury, total
Nickel, dissolved
Nickel, total
Selenium, dissolved
Selenium, total
Zinc, dissolved
Zinc, total
Basic variables to be monitored at all GEMS/Water stations:
R - Basic variables for river stations only
L - Basic variables for lake/reservoir stations only
GW - Basic variables for groundwater stations only
R,L - Basic variables for river, lake/reservoir stations only
GRF - Essential for Global River Flux monitoring stations
Organic contaminants
Aldicarb
Aldrin
Altrazine
Benzene
2, 4-D
DDTs
Dieldrin
Lindane
Total hydrocarbons
Total chlorinated hydrocarbons
Total polyaromatic
hydrocarbons
PCBs
Phenols
64
Planning of water-quality monitoring systems
Table 3. DPSIR39 framework for water quality of surface- and groundwater ecosystems
Service
and use
(drivers)
Pressures
Parameter
State
Impact
Human health,
drinking-water
Pollution
Agriculture
Municipal/
industrial, energy
Ecosystem
stability,
structure and
health
Tourism and
recreation
Runoff,
pollution from
fertilizer and
pesticide use
Pollution from
effluents,
construction and
other supporting
infrastructural
impacts
Human
activities;
climate
change and
variability
Pollution
Total coliform
Salinity
Nutrients
Temperature
Parasites
Faecal coliform
Nutrients
Temperature
pH
Pathogens
Pathogens
Chlorophyll a
DO
Conductivity
Chlorophyll a
POPs
Pathogens
Pathogens
Major ions
Nutrients
DOC
Pesticides
Organic
contaminants
DO
Chlorophyll a
Suspended
solids
Other contaminants
such as metals
Nitrogen
Turbidity
Trace metals
BOD and COD
Phosphorus
Heavy metals
(particularly
in sediment),
radioactivity, acid
mine drainage
Suspended
solids
Gastrointestinal
outbreaks;
potential death
especially of
vulnerable
persons
Lost
productivity
and economic
losses
Water
guidelines and
standards
Response
Treatment
plants
Eutrophication,
pesticide
and faecal
contamination
of receiving
waters
Thermal and
contaminant
pollution of
receiving waters
affect food
chains, biological
productivity
and species
composition
Loss of
species,
altered food
webs
Green belts
and riparian
buffer strips
Guidelines and
standards
Prevention of
direct inputs
contaminants
Treatment facilities
Appropriate
practices to
minimize
impacts
Polluter pays
principle
Appropriate
treatment
facilities for
point sources
but limited
responses
for climate
change and
variability
Source: UNEP GEMS/Water Technical Advisory Paper No. 2, May 2005
39
Drivers-Pressures-State-Impact-Responses
Increased/
decreased
biological
productivity
Closed
beaches,
leisure
boating
restrictions
and effects
on other
water uses
Guidelines
and
standards
Water-use
advisories
65
Tables
Table 4. Selection of variables for assessment of water quality in relation to .
non-industrial water use
Background
monitoring
Aquatic life
and fisheries
Temperature
xxx
xxx
Colour
xx
Drinkingwater
sources
Recreation
and health
Agriculture/
irrigation
Livestock
watering
General variables
Odour
Suspended
solids
x
xx
xx
xx
xx
xxx
xxx
xxx
xxx
Turbidity/
transparency
x
xx
xx
xx
Conductivity
xx
x
x
x
x
x
xxx
Total dissolved
solids
pH
xxx
xx
x
DO
xxx
xxx
x
x
xx
x
xx
xx
Ammonia
x
xxx
x
Nitrate/nitrite
xx
x
xxx
Phosphorus or
phosphate
xx
Hardness
Chlorophyll a
x
x
xx
x
xx
Nutrients
xx
Organic matter
TOC
xx
COD
xx
xx
x
BOD
xxx
xxx
x
xx
Major ions
Sodium
x
x
Potassium
x
Calcium
x
Magnesium
xx
x
Chloride
xx
x
Sulphate
x
x
xxx
x
x
xxx
x
Other inorganic variables
Fluoride
xx
Boron
Cyanide
x
x
x
x
xx
x
66
Planning of water-quality monitoring systems
Table 4 continued
Aquatic life
and fisheries
Drinkingwater
sources
Heavy metals
xx
Arsenic and
selenium
Background
monitoring
Recreation
and health
Agriculture/
irrigation
Livestock
watering
xxx
x
x
xx
xx
x
x
Oil and
hydrocarbons
x
xx
x
x
Organic solvents
x
xxx
x
Trace elements
Organic contaminants
xx
Phenols
x
xx
x
Pesticides
xx
xx
x
Surfactants
x
x
x
Faecal coliforms
xxx
xxx
xxx
Total coliforms
xxx
xxx
x
Pathogens
xxx
xxx
x
x
Microbiological indicators
xx
X – XXX - Low to high likelihood that the concentration of the variable will be affected and the more important it
is to include the variable in a monitoring programme. Variables stipulated in local guidelines or standards for a
specific water use should be included when monitoring for that specific use.
Source: D. Chapman [Ed.], 1996
67
Tables
Table 5. Selection of variables for the assessment of water quality in relation to some key
industrial uses
Heating
Cooling
Power
generation
Iron and
steel
Pulp and
paper
xxx
x
Petrol
Food
processing
General variables
Temperature
Colour
xxx
xxx
x
x
xx
Odour
xxx
Suspended
soils
xxx
Turbidity
xx
Conductivity
x
x
Dissolved
solids
xx
xx
xxx
pH
x
xxx
DO
xxx
Hardness
xxx
xxx
xx
xx
x
xxx
xx
xx
xx
xx
xx
xxx
x
xxx
xxx
xx
xx
xxx
xxx
x
xxx
x
xxx
xx
xxx
xxx
xxx
x
xx
Nutrients
Ammonia
xxx
x
x
Nitrate
Phosphate
x
Organic matter
COD
x
xx
xxx
xxx
x
xxx
x
x
x
xxx
x
xxx
xxx
x
x
Major ions
Calcium
Magnesium
Carbonate
components
xx
Chloride
x
Sulphate
x
xx
xx
x
xxx
xxx
x
xx
xx
xx
x
xxx
Other inorganic variables
Hydrogen
sulphide
xxx
x
Silica
xx
xx
xx
x
x
Fluoride
x
x
x
xx
x
xx
Trace elements
Aluminium
Copper
x
x
x
x
Iron
xx
x
x
x
Manganese
xx
x
x
x
Zinc
x
xx
68
Planning of water-quality monitoring systems
Table 5 continued
Heating
Cooling
Power
generation
Iron and
steel
x
x
x
Pulp and
paper
Petrol
Food
processing
x
x
Organic contaminants
Oil and
hydrocarbons
x
Organic
solvents
x
Phenols
x
Pesticides
Surfactants
x
x
x
x
x
Microbiological indicators
Pathogens
xxx
X – XXX - Low to high likelihood that the concentration of the variable will be affected and the more important it
is to include the variable in a monitoring programme. The precise selection of variables depends on the required
quality of the water in the individual industrial processes and any standards or guidelines that are applied.
Source: D. Chapman (Ed.), 1996
69
Tables
Table 6. Selection of variables for the assessment of water quality in relation to
non-industrial pollution sources
Sewage and
municipal
wastewater
Urban
runoff
Agricultural
activities
Waste
disposal to
land
Solid
hazardous
municipal
chemicals
Long-range
atmospheric
transport
General variables
Temperature
x
x
x
Colour
x
x
x
Odour
x
x
x
Residues
x
x
x
xxx
xxx
xx
Suspended
solids
xxx
xx
xxx
xx
xx
Conductivity
xx
xx
xx
xxx
xxx
xxx
pH
x
x
x
xx
xxx
xxx
Redox
potential (Eh)
x
x
x
xxx
xxx
xxx
xxx
xxx
x
x
x
Ammonia
xxx
xx
xxx
xx
Nitrate/nitrite
xxx
xx
xxx
xx
Organic
nitrogen
xxx
xx
xxx
xx
Phosphorus
compounds
xxx
xx
xxx
x
Alkalinity
DO
Hardness
xx
xxx
x
x
Nutrients
xxx
x
Organic matter
TOC
x
x
x
COD
xx
xx
x
xxx
xxx
BOD
xxx
xx
xxx
xxx
xx
Sodium
xx
xx
xx
Potassium
x
x
x
Calcium
x
x
x
Magnesium
x
x
x
xx
xx
Major ions
Carbonate components
Chloride
xxx
xx
xxx
Sulphate
x
x
x
xx
x
xxx
Other inorganic variables
Sulphide
xx
Silica
x
Fluoride
x
Boron
x
x
70
Planning of water-quality monitoring systems
Table 6 continued
Sewage and
municipal
wastewater
Urban
runoff
Agricultural
activities
Waste
disposal to
land
Solid
hazardous
municipal
chemicals
Long-range
atmospheric
transport
Trace elements
Aluminium
xx
Cadmium
x
xxx
xxx
x
Chromium
x
xxx
xx
x
xxx
xx
x
xxx
xx
x
xx
Copper
x
x
Iron
xx
xx
Lead
xx
xxx
Mercury
x
xx
Zinc
xx
xxx
xx
xxx
xxx
xxx
xx
xxx
xx
x
x
Arsenic
x
xxx
xx
xxx
Selenium
x
xxx
x
x
Organic contaminants
Fats
x
x
Oil and
hydrocarbons
xx
xxx
xx
x
Organic
solvents
x
x
xxx
xxx
Methane
Phenols
xxx
x
Pesticides
Surfactants
x
xxx
xx
xx
xx
xx
xxx
x
xxx
x
Microbiological indicators
Faecal
coliforms
xxx
Other
pathogens
xxx
xx
xx
xxx
xx
xxx
X – XXX - Low to high likelihood that the concentration of the variable will be affected and the more important it
is to include the variable in a monitoring programme.
The final selection of variables is also dependent on the nature of the water body.
71
Tables
Table 7. Selection of variables for the assessment of water quality in relation to some
common industrial sources of pollution
Food
processing
Mining
Oil
extraction/
refining
Chemical/
pharmaceutical
Pulp
and
paper
Metallurgy
Machine
production
Textiles
General variables
Temperature
x
x
x
x
x
x
x
x
Colour
x
x
x
x
x
x
x
x
Odour
x
x
x
x
x
x
x
x
Residues
x
x
x
x
x
x
x
x
Suspended
solids
x
xxx
xxx
x
xxx
xxx
xxx
xxx
Conductivity
xxx
xxx
xxx
x
xxx
xxx
xxx
xxx
pH
xxx
xxx
x
xxx
x
xxx
x
x
x
x
x
x
x
x
x
x
xxx
xxx
xxx
xxx
xxx
x
x
xxx
x
x
x
x
x
xx
x
x
xx
xx
x
x
x
x
xx
x
x
x
Redox
potential (Eh)
DO
Hardness
Nutrients
Ammonia
xxx
Nitrate/nitrite
xx
Organic
nitrogen
xx
x
Phosphorus
compounds
xx
xx
x
x
x
x
x
Organic matter
TOC
x
x
x
xx
xxx
x
x
x
COD
x
x
x
xxx
xxx
x
x
x
BOD
xxx
x
xxx
xx
xxx
x
x
xxx
Major ions
Sodium
x
x
x
x
x
Potassium
x
x
x
x
x
Calcium
x
x
x
x
x
xx
x
x
x
x
Magnesium
x
x
x
x
Carbonate
components
x
x
x
x
x
Chloride
xx
xxx
xx
xx
x
x
x
xxx
Sulphate
x
x
xx
xx
xxx
x
x
x
Sulphide
x
xxx
xxx
xxx
xxx
Silica
x
x
Other inorganic variables
Fluoride
x
x
xx
Boron
x
Cyanide
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
xxx
xxx
xx
Trace elements
Heavy metals
xxx
xx
xx
x
Arsenic
x
x
x
Selenium
x
x
x
x
x
x
72
Planning of water-quality monitoring systems
Table 7 continued
Food
processing
Mining
Oil
extraction/
refining
Chemical/
pharmaceutical
Pulp
and
paper
Metal
lurgy
Machine
production
Textiles
Organic contaminants
Fats
xx
Oil and
hydrocarbons
xx
xxx
Organic
solvents
Phenols
x
Pesticides
x
xx
xx
xx
xxx
xxx
xxx
xxx
x
xxx
xxx
x
xxx
x
x
xxx
x
x
x
x
xxx
Other
organics
Surfactants
xx
xx
x
xx
X – XXX - Low to high likelihood that the concentration of the variable will be affected and the more important it
is to include the variable in a monitoring programme. The final selection of variables to be monitored depends
on the products manufactured or processed together with any compounds present in local industrial effluents.
Any standards or guidelines for specific variables should also be taken into consideration.
73
Tables
Table 8. Recommended annual sampling frequencies for GEMS/Water stations
Station types
Baseline
Type of water
Rivers/streams
Lakes/reservoirs
Minimum – 4,
including high- and
low-water stages
Minimum – 1 at
turnover (sampling at
lake outlet)
Optimum – 24,
i.e. fortnightly
sampling, and weekly
for total suspended
solids
Optimum – 1 at
turnover and 1 vertical
profile at end of
stratification period
Aquifers
Minimum – 12 for large Eutrophication issue –
Minimum – 1 for
drainage area
12, including twice
large, stable aquifers
(c. 100 000 km2)
monthly during summer
Trend
Maximum – 24 for
small drainage area
(c. 10 000 km2)
Other issues
Minimal – 1 at turnover
Maximal – 2: 1 at
turnover and 1 at
maximum thermal
stratification
Maximum – 4 for
small, alluvial aquifers
Karstic aquifers: same as
rivers
Large basins (> 200 000 km2) (1); 6 for some
particulate metals (2); 12 for all other variables
Global river flux
Small basins (< 200 000 km2) (1) 24 for basic
monitoring variables (3); 12 for expanded
nutrients, organic contaminants and some
expanded metal monitoring (4); 6 for some
particulate analysis (2)
(1) For global river flux stations: continuous record of water discharge and weekly sampling for TSS are
recommended.
(2) For particulate arsenic, cadmium, chromium, copper, lead, mercury, selenium, zinc
(3) For temperature, pH, electrical conductivity, DO, calcium, magnesium, sodium, potassium, chloride,
sulphate, alkalinity, nitrate plus nitrite, total phosphorus filtered and unfiltered, silica, chlorophyll a, dissolved
and particulate organic carbon, dissolved and particulate organic nitrogen
(4) For dissolved and particulate fractions of aluminium, iron and manganese; and for dissolved arsenic,
cadmium, chromium, copper, lead, mercury, selenium and zinc
Source: GEMS/Water Operational Guide v.3.1
74
Planning of water-quality monitoring systems
Table 9. Examples of responsibilitie40 of staff on a water-quality monitoring programme
Responsibilities of the programme manager
• Planning of water-quality monitoring activities
• Coordination with regional centres, collaborating agencies, participating laboratories and others
not under his/her direct control
• Procurement of necessary equipment and consumable supplies
• Arranging suitable transport
• Recruitment of staff
• Training of staff
• Preparation of training manuals
• Safety in the field and in the laboratory
• Preparation of SOPs
• Organizing and managing central office facilities for the storage, handling, interpretation and distribution of data
• Supervising and evaluating the performance of all staff
• Reviewing and evaluating procedures
• Preparation of reports and dissemination of the findings of the monitoring programme
Responsibilities of field staff
• Undertaking sampling expeditions in accordance with a planned programme
• Obtaining samples according to SOPs
• Sample handling: labelling sample bottles, preparing samples, etc.
• Performing on-site measurements with proper devices
• Maintenance of equipment used in the field
• Performing field tests for selected variables
Responsibilities of laboratory staff
Laboratory chief
• Responsible for laboratory management
• Determining and procuring the equipment and supplies needed
• Ensuring that SOPs are being followed
• Quality-control of analytical procedures
• Enforcing safety precautions and procedures
Laboratory technician (analyst)
• Preparation and carrying-out of analytical work in the laboratory
• Teaching the assistants how to use various items of laboratory equipment and carry out certain
analyses
Laboratory assistant
• Use of various items of laboratory equipment
• Preparation of reagent solutions
• Carrying out of certain analyses
40
Examples of what may be expected of the different types of staff, although it may not be complete for any
specific situation.
Tables
75
Table 10. Management documents needed (ISO/IEC 17025, 2005) to implement the
quality-assurance programme (quality manual)
• A quality policy statement, including objectives and commitments
• The organization and management structure of the project, its place in any parent organization
and relevant organizational charts
• The relationship between management, technical operations, support services and the quality
system
• Procedures for control and maintenance of documentation
• Job descriptions for key staff and reference to the job descriptions of other staff
• Identification of approved signatories
• Procedures for ensuring traceability of all paperwork, data and reports
• The laboratory’s scope for calibrations and tests
• Arrangements for reviewing all new projects to ensure that there are adequate resources to
manage them properly
• Reference to the calibration, verification and testing procedures used
• Procedures for handling calibration and test items
• Reference to the major equipment and reference measurement standards used
• Reference to procedures for calibration, verification and maintenance of equipment
• Reference to verification practices, including interlaboratory comparisons, proficiency testing
programmes, use of reference materials and internal quality-control schemes
• Procedures to be followed for feedback and corrective actions whenever testing discrepancies or
departures from documented procedures are detected
• Complaints procedure
• Procedures for protecting confidentiality and property rights
• Procedures for audit and review
Annex 1. Description of the main water-quality variables
1. General variables
Temperature
The temperature of surface waters is influenced by latitude, altitude, season, time of day, air
circulation, cloud cover and the flow and depth of the water body. In turn, temperature
affects physical, chemical and biological processes in water bodies and, therefore, the
concentration of many variables. As water temperature increases, the rate of chemical
reactions generally increases, together with the evaporation and volatilization of substances
from the water. Increased temperature also decreases the solubility of gases in water, such
as oxygen (O2), carbon dioxide (CO2), nitrogen (N2), methane (CH4) and others. The metabolic
rate of aquatic organisms is also related to temperature and, in warm waters, respiration
rates increase, leading to increased oxygen consumption and increased decomposition of
organic matter. Growth rates also increase (this is most noticeable for bacteria and
phytoplankton, which double their populations in very short time periods), leading to
increased water turbidity, macrophyte growth and algal blooms, when nutrient conditions
are suitable.
Measurements of temperature are required in studies of the self-purification of rivers and
reservoirs and for the control of waste-treatment plants. They are important in relation to
fishlife and other biological activity and are also necessary for cooling purposes, for process
use in industry and heat/cold storage for thermal energy. Identification of the water source,
such as deep wells, is often possible by temperature measurement alone. The temperature
of drinking-water has an influence on its taste. It is also important in connection with bathing
and agricultural irrigation.
Colour
The colour and turbidity of water indicate the depth to which light is transmitted. This, in
turn, controls the amount of primary productivity that is possible by controlling the rate of
photosynthesis of the algae present. The visible colour of water is the result of the different
wavelengths not absorbed by the water itself or the result of dissolved and particulate
substances present. It is possible to measure both true and apparent colour in water.
Minerals such as ferric hydroxide and organic substances such as humic acids give true
colour to water. True colour can be measured in a sample only after filtration or
centrifugation. Apparent colour is caused by coloured particulates and the refraction and
reflection of light on suspended particulates. Polluted water may, therefore, have quite a
strong apparent colour.
Different species of phyto- and zooplankton can also give water an apparent colour. A dark
or blue-green colour can be caused by blue-green algae, a yellow-brown colour by diatoms
or dinoflagellates and reds and purples by the presence of zooplankton such as Daphnia
sp. or copepods.
Taste and odours
Water odour is usually the result of labile, volatile organic compounds and may be
produced by phytoplankton and aquatic plants or decaying organic matter. Industrial and
human waste can also create odours, either directly or as a result of stimulating biological
activity. Organic compounds, inorganic chemicals, oil and gas can all impart odour to
water, although an odour does not automatically indicate the presence of harmful
substances. Regarding groundwater, hydrogen sulphide (H2S), has a strong odour, which is
easily recognized by the human sense of smell.
Annex 1. Description of the main water-quality variables
77
Residue and total suspended solids
The term “residue” applies to the substances remaining after evaporation of a water
sample and its subsequent drying in an oven at a given temperature. It is approximately
equivalent to the total content of dissolved and suspended matter in the water since half
the bicarbonate (the dominant anion in most waters) is transformed into CO2 during this
process. The term “solids” is widely used for the majority of compounds which are present
in natural waters and remain in a solid state after evaporation (some organic compounds
will remain in a liquid state after the water has evaporated). TSS and TDS correspond to
non-filterable and filterable residue, respectively.
Suspended matter, turbidity and transparency
The type and concentration of suspended matter control the turbidity and transparency of
the water. Suspended matter consists of silt, clay, fine particles of organic and inorganic
matter, soluble organic compounds, plankton and other microscopic organisms.
Such particles vary in size from approximately 10 nm in diameter to 0.1 mm in diameter,
although it is usually accepted that suspended matter is the fraction that will not pass
through a 0.45 μm pore diameter filter. Turbidity results from the scattering and absorption
of incident light by the particles and the transparency is the limit of visibility in the water.
Both can vary seasonally, according to biological activity in the water column and surface
runoff carrying soil particles. Heavy rainfall can also result in hourly variations in turbidity.
At a given river station, turbidity can often be related to TSS, especially where there are
large fluctuations in suspended matter. Therefore, following an appropriate calibration,
turbidity is sometimes used as a continuous, indirect measurement for TSS.
Water transparency or clarity is a function of the concentration of suspended solids in the
water column. A marked attenuation in light intensity with depth in turbid waters will result
in a greater absorption of solar energy near the surface. The warmer surface water may
reduce oxygen transfer from the air to the water and will decrease density and stabilize
stratification, thus slowing or precluding vertical mixing. Reduced light penetration will
decrease photosynthesis and will have a direct influence on the amount of biological
production occurring within a body of water. A lower depth of light penetration may
impact sight-feeding fish, zooplankton migrations and benthic invertebrate reproduction.
Transparency can be measured easily in the field and is, therefore, included in many
regular sampling programmes, particularly in lakes and reservoirs, to indicate the level of
biological activity. It is determined by a Secchi disc. Turbidity should be measured in the
field but, if necessary, samples can be stored in the dark for not more than 24 hours.
Conductivity
Conductivity, or specific conductance, is a measure of the ability of water to conduct an
electric current. It is sensitive to variations in dissolved solids and major ions, mostly
mineral salts. In addition to being a rough indicator of mineral content when other
methods cannot easily be used, conductivity can be measured to establish a pollution
zone, e.g. around an effluent discharge, or the extent of influence of runoff waters. It is
usually measured in situ with a conductivity meter, and may be continuously measured
and recorded. Such continuous measurements are particularly useful in rivers and
groundwater for the management of temporal variations in total dissolved solids and
major ions.
pH, acidity and alkalinity
The acidification of lakes is a real risk, especially in countries where the natural salt
concentration is low, as is the case in the Nordic countries and North America, e.g. the
78
Planning of water-quality monitoring systems
Canadian Shield. Alkalinity41 is a measure of the buffering capacity of water or the capacity
of bases to neutralize acids. Measuring alkalinity is important in determining a stream’s
ability to neutralize acidic pollution from rainfall or wastewater. Alkalinity does not refer to
pH, but rather the ability of water to resist change in pH. The presence of buffering materials
helps neutralize acids as they are added to the water. These buffering materials are primarily
the bases bicarbonate (HCO3-) and carbonate (CO32 -), and occasionally hydroxide (OH- ),
borates, silicates, phosphates, ammonium, sulphides and organic ligands. Where limestone
and sedimentary rocks and carbonate-rich soils are predominant, groundwater will often
have high alkalinity.
Original alkalinity values are very small (and may differ for groundwater or saline surface
water) and the buffering capacity therefore is extremely low. Because of relatively high
concentrations of natural humic substances, the original pH is usually distinctly below 7.0.
Airborne loading of different acidifying compounds such as sulphates and nitrates can
lower pH values significantly so that harmful biological consequences occur. Some fish
species are especially sensitive to acidification.
The pH is an important variable in WQ assessment as it influences many biological and
chemical processes within a water body and all processes associated with water supply and
treatment. When measuring the effects of an effluent discharge, it can be used to help
determine the extent of the effluent plume in the water body.
The pH is a measure of the acid balance of a solution. The pH scale runs from 0 to 14
(i.e. very acidic to very alkaline), with pH 7 representing a neutral condition. At a given
temperature, pH (or the hydrogen ion activity) indicates the intensity of the acidic or basic
character of a solution and is controlled by the dissolved chemical compounds and
biochemical processes in the solution. In unpolluted waters, pH is principally controlled by
the balance between the carbon dioxide, carbonate and bicarbonate ions, as well as other
natural compounds such as humic and fulvic acids.
Oxygenation conditions
Oxygen is without doubt the most important gas that dissolves in water from the
atmosphere, owing to the fact that it is the dominant biotope factor regulating life in waters.
The oxygen content of natural waters varies with temperature, salinity, turbulence, the
photosynthetic activity of algae and plants, and atmospheric pressure. The solubility of
oxygen decreases as temperature and salinity increase. DO can also be expressed in terms
of percentage saturation, and levels less than 80 per cent saturation in drinking-water can
usually be detected by consumers as a result of poor odour and taste.
Variations in DO can occur seasonally – or even over 24 hour periods – in relation to
temperature and biological activity (i.e. photosynthesis and respiration). Biological
respiration, including that related to decomposition processes, reduces DO concentrations.
In still waters, pockets of high and low concentrations of DO can occur, depending on the
rates of biological processes. Waste discharges high in organic matter and nutrients can lead
to decreases in DO concentrations as a result of increased microbial activity (respiration)
occurring during the degradation of the organic matter. In severe cases of reduced oxygen
concentrations (whether natural or man-made), anaerobic conditions can occur, particularly
close to the sediment-water interface as a result of decaying, sedimenting material.
Carbon dioxide
The other gas measured in WQM is CO2. There is a certain balance between O2 and CO2
concentrations, because the changes of these gases in lakes are significantly connected to
biological reactions. CO2 is highly soluble in water and atmospheric CO2 is absorbed at the
41
From http://bcn.boulder.co.us/basin/data/BACT/info/Alk.html
Annex 1. Description of the main water-quality variables
79
air-water interface. In addition, CO2 is produced within water bodies by the respiration of
aquatic biota during aerobic and anaerobic heterotrophic decomposition of suspended and
sedimented organic matter. CO2 dissolved in natural water is part of an equilibrium
involving bicarbonate and carbonate ions. The concentrations of these forms are
dependent to some extent on the pH.
The pH is a measure of the acid balance of a solution. The pH scale runs from 0 to 14 (i.e.
very acidic to very alkaline), with pH 7 representing a neutral condition. At a given
temperature, the pH (or the hydrogen ion activity) indicates the intensity of the acidic or
basic character of a solution and is controlled by the dissolved chemical compounds and
biochemical processes in the solution. In unpolluted waters, pH is principally controlled by
the balance between the carbon dioxide, carbonate and bicarbonate ions, as well as other
natural compounds such as humic and fulvic acids.
Oxygenation conditions
Oxygen is without doubt the most important gas that dissolves in water from the
atmosphere, owing to the fact that it is the dominant biotope factor regulating life in
waters. The oxygen content of natural waters varies with temperature, salinity, turbulence,
the photosynthetic activity of algae and plants, and atmospheric pressure. The solubility of
oxygen decreases as temperature and salinity increase. DO can also be expressed in terms
of percentage saturation, and levels less than 80 per cent saturation in drinking-water can
usually be detected by consumers as a result of poor odour and taste.
Variations in DO can occur seasonally – or even over 24 hour periods – in relation to
temperature and biological activity (i.e. photosynthesis and respiration). Biological
respiration, including that related to decomposition processes, reduces DO concentrations.
In still waters, pockets of high and low concentrations of DO can occur, depending on the
rates of biological processes. Waste discharges high in organic matter and nutrients can
lead to decreases in DO concentrations as a result of increased microbial activity
(respiration) occurring during the degradation of the organic matter. In severe cases of
reduced oxygen concentrations (whether natural or man-made), anaerobic conditions can
occur, particularly close to the sediment-water interface as a result of decaying,
sedimenting material.
Carbon dioxide
The other gas measured in WQM is CO2. There is a certain balance between O2 and CO2
concentrations, because the changes of these gases in lakes are significantly connected to
biological reactions. CO2 is highly soluble in water and atmospheric CO2 is absorbed at the
air-water interface. In addition, CO2 is produced within water bodies by the respiration of
aquatic biota during aerobic and anaerobic heterotrophic decomposition of suspended and
sedimented organic matter. CO2 dissolved in natural water is part of an equilibrium
involving bicarbonate and carbonate ions. The concentrations of these forms are
dependent to some extent on the pH.
Free CO2 is that component in gaseous equilibrium with the atmosphere, whereas total
CO2 is the sum of all inorganic forms of carbon dioxide, i.e. CO2, carbonic acid (H2CO3 ),
HCO3- and CO32 -.
Chlorophyll
The green pigment chlorophyll (which exists in three forms: chlorophyll a, b and c) is
present in most photosynthetic organisms and provides an indirect measure of algal
biomass and an indication of the trophic status of a water body. It is usually included in
assessment programmes for lakes and reservoirs and is important for the management of
80
Planning of water-quality monitoring systems
water abstracted for drinking-water supply, since excessive algal growth makes water
unpalatable or more difficult to treat.
In waters with little sediment input from the catchment or with little re-suspension,
chlorophyll can give an approximate indication of the quantity of material suspended in the
water column. The growth of planktonic algae in a water body is related to the presence of
nutrients (principally nitrates and phosphates), temperature and light. The correlation
between different nutrients and chlorophyll a can provide a good basis for discussions of
the relevant minimum factors of primary production.
Salinity
Salinity is a general term42, 43 used to describe the levels of different salts such as sodium
chloride, magnesium, calcium sulphates and bicarbonates. The presence of salt can
restrict abstraction of water for drinking purposes. If water abstraction is excessive,
intruding saltwater can contaminate the groundwater. High salinity is a frequent problem
in arid and coastal areas.
Salinity is the sum weight of many different elements within a given volume of water. It
has always been the case that the conversion of a precise salinity as a concentration to an
amount of substance (sodium chloride, for instance) requires knowing much more about
the sample and the measurement than just the weight of the solids upon evaporation (one
method of determining salinity). For example, volume is influenced by water temperature,
while the composition of the salts is not a constant. Saline waters from inland seas can
have a composition that differs from those of the ocean.
The salinity of lake waters depends primarily on the quality of the bedrock, the soil of the
watershed, where the lake is situated and where its water source is. There are great
differences in salinity between different geological areas. Freshwaters contain alkali and
alkaline earth bicarbonate and carbonate, sulphate, chloride in dilutions and largely
undissociated silicic acids. In smaller quantities, there are a great number of different
elements (such as the important nutrients phosphorus and nitrogen, as well as aluminium,
iron, manganese, copper, zinc, etc.), which can be measured everywhere in the world.
Regarding groundwater, the formation of saline groundwater and the migration and/or mixing
of these categories of groundwater are put into motion by certain natural drivers (deposition of
marine sediments, sea-level variations, meteorological processes and the hydrological cycle,
climate change), anthropogenic drivers (coastal protection, land reclamation and drainage;
groundwater abstraction, irrigation, disposal of waste and pollution).
More information on this issue, see Section 4. Major ions.
2. Nutrients
Nitrogen and phosphorus are the major nutrients causing eutrophication of surface waters.
These nutrients originate partially from natural sources but mostly from the anthropogenic
sources in areas affected by various human activities. Nitrogen loading arises mainly from
diffuse sources such as agriculture, while phosphorus loading is dominated by point
sources, such as municipal sewerage waters or industrial effluents, but also by agriculture,
in particular surface runoff. Both nutrients can infiltrate the soil and be transported by
groundwater to discharge zones, for example baseflow in rivers or drainage pipes. When
transported by the groundwater, chemical reactions, e.g. denitrification, can take place,
depending on the reactivity of the subsurface and redox conditions.
42
Source: Wikipedia
43 Salinity
in Australian English and North American English may also refer to the salt content of soil.
Annex 1. Description of the main water-quality variables
81
Excessive loading of nitrogen and phosphorus may drastically change the biological
structure of a water body leading to such undesirable phenomena as blue-green algal
blooms, pronounced overgrowth of macrophytes or even fish kills caused by intensive
decomposition of organic material and subsequent oxygen deficiency in the water
column. Drinking-water contaminated with nitrate poses a health risk to infants. In most
cases, phosphorus is the limiting nutrient for algal growth in lakes, especially in
oligotrophic-mesotrophic conditions. The regulating role of nitrogen becomes more
important in eutrophic or hypertrophic lakes and marine waters.
Most primary producers (e.g. phytoplankton, periphyton and macrophytes) can only
utilize dissolved forms of nutrients such as ammonium, nitrite, nitrate, urea and
phosphate. Hence, the total concentrations of nitrogen and phosphorus do not
necessarily reveal the limiting nutrient of the lake ecosystem.
3. Organic matter
Organic matter, measured by DO, BOD and ammonium, constitute key indicators of the
oxygen content of water bodies.
Concentrations of these parameters normally increase as a result of organic pollution
caused by discharges from wastewater-treatment plants, industrial effluents and
agricultural runoff. Severe organic pollution may lead to rapid de-oxygenation of river
water, a high concentration of ammonia and the disappearance of fish and aquatic
invertebrates.
The most important sources of organic waste load are: household wastewater; paper and
food-processing industries (among others); and, occasionally, silage effluents and slurry
from agriculture. Increased industrial and agricultural production, coupled with a greater
percentage of the population being connected to sewerage systems, initially resulted in
increases in the discharge of organic waste into surface water in most developed
countries. Over the past 15-30 years, however, the biological treatment of wastewater
has increased and organic discharges have consequently decreased.
Measurement of TOC or DOC is a much more rapid means of determining the organic
content of water and wastewater than is the measurement of BOD. If the relative
concentrations of organic compounds in the samples do not change greatly, empirical
relationships can be established between TOC and BOD or COD to permit speedy and
convenient estimations of the latter. Measurement of TOC can be used to monitor
processes for the treatment or removal of organic contaminants without undue
dependence on the oxidation states and is valid at low concentrations.
Humus is formed by the chemical and biochemical decomposition of vegetative residues
and from the synthetic activity of microorganisms. Humus enters water bodies from the
soil and from peat bogs or it can be formed directly within water bodies as a result of
biochemical transformations. It is operationally separated into fulvic and humic acid
fractions, each being an aggregate of many organic compounds of different masses.
Natural organic compounds are not usually toxic but exert major controlling effects on
the hydrochemical and biochemical processes in a water body. Some natural organic
compounds significantly affect the quality of water for certain uses, especially those
which depend on organoleptic properties (taste and smell). During chlorination for
drinking-water disinfection, humic and fulvic acids act as precursor substances in the
formation of tribalomethanes such as chloroform. In addition, substances included in
aquatic humus determine the speciation of heavy metals and some other pollutants
because of their high complexing ability. As a result, humic substances affect the toxicity
and mobility of metal complexes. Measurement of the concentrations of these
substances can, therefore, be important for determining anthropogenic impacts on water
bodies.
82
Planning of water-quality monitoring systems
Organic matter44 in groundwater plays important roles in controlling geochemical
processes by acting as proton donors/acceptors and as pH buffers, by affecting the
transport and degradation of pollutants and by participating in mineral dissolution/
precipitation reactions.
4. Major ions
The most common elements which have been monitored from inland surface waters are
sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), chloride (Cl) and sulphur (S).
Sodium in water exists principally as the cation Na+. Potassium does not exist in nature as a
free element, it forms salts as chloride, bromide, sulphate, nitrate and aluminium silicates.
Potassium is an essential element for plant growth. Calcium is the fifth most abundant element
in rocks and soils on Earth. In surface waters, it is one of the most abundant cations because of
the weathering of rocks and soils. It occurs mostly as the Ca2+ ion but complexes can also occur.
Magnesium is the eighth most abundant element on Earth. In water it exists largely as the Mg2+
ion. It also forms complexes. Chloride (Cl) does not occur freely in nature. The chloride ion is
the principal ion in seawater and is widely distributed in the environment as salts with sodium,
potassium and calcium. Sulphur is the ninth most abundant element on Earth. Sulphur
compounds are widely distributed in minerals and rocks. In water, sulphates occur mainly as
free anion SO , and form ion pairs with Ca2+, Mg2+, Na+, Fe2+, Fe3+ and Mn2+.
Sulphide formation in surface waters is principally through anaerobic, bacterial decay of
organic substances in bottom sediments and stratified lakes and reservoirs. Traces of sulphide
ion occur in unpolluted bottom sediments from the decay of vegetation but the presence of
high concentrations often indicates the occurrence of sewage or industrial wastes. Under
aerobic conditions, the sulphide ion converts rapidly to sulphur and sulphate ions. When
appreciable concentrations of sulphide occur, toxicity and the strong odour of the sulphide ion
make the water unsuitable for drinking-water supplies and other uses.
In connection with drinking-water supply, the variable water hardness is often used. Water
hardness expresses the sum of all the metallic cations, except for alkali metals. The principal
ions responsible for water hardness are calcium and magnesium. The following types of water
hardness are commonly used:
•
Total hardness is equivalent to the total concentration of Ca2+ and Mg2+, as well as the other
bivalent ions, such as Fe2+, Mn2+, Ba2+ and Sr2+;
•
Carbonate hardness;
•
Non-carbonate hardness.
In the monitoring of lakes and groundwater, it is important to define the natural status of the
salinity and the natural concentrations of the relevant elements. In the preparation of monitoring
programmes, all possible sources of loading factors in this sense should be clarified.
5. Other inorganic variables
Silica: silica is widespread and always present in surface water and aquifers, existing in
dissolved, suspended and colloidal states. Dissolved forms are represented mostly by silicic
acid, products of its dissociation and association, and organo-silicon compounds.
44
http://water.usgs.gov/ogw/pubs/ofr0289/ga_organic.htm
Annex 1. Description of the main water-quality variables
83
Reactive silicon (principally silicic acid but usually recorded as dissolved silica (SiO2) or
sometimes as silicate (H4SiO4) results mainly from the chemical weathering of siliceous
minerals. Silica may be discharged into water bodies with wastewater from industries using
siliceous compounds in their processes such as potteries, glassworks and abrasive manufacture.
Fluoride: fluoride originates from hydrothermal/volcanic sources and the weathering of fluoridecontaining minerals and enters surface waters with runoff and aquifers through direct contact.
Liquid and gas emissions from certain industrial processes (such as metal- and chemical-based
manufacturing) can also contribute fluoride ions (F-) to water bodies. Fluoride mobility in water
depends, to a large extent, on the Ca2+ ion content, since fluoride forms low-solubility
compounds with divalent cations. Other ions that determine water hardness can also increase
F- solubility.
During weathering45 and circulation of water in rocks and soils, fluoride can be leached out and
dissolved in groundwater and thermal gases. The fluoride content of groundwater varies greatly,
depending on the geological settings and type of rocks. The most common fluoride-bearing
minerals are fluorite, apatite and micas. Fluoride problems tend, therefore, to occur in places
where these minerals are most abundant in the host rocks. Aquifers from crystalline rocks,
especially (alkaline) granites (deficient in Ca) are particularly sensitive to relatively high fluoride
concentrations.
Fluoride in groundwater: the measurement of fluoride content is especially important when a
water body is used for drinking-water supply. At high concentrations, fluoride is toxic to humans
and animals and can cause bone disease. A slight increase in natural concentrations, however,
can help prevent dental caries, although, at higher concentrations (above 1.5-2.0 mg l–1), mottling
of teeth can occur (WHO, 1984). Where fluoride is known to occur or can be anticipated, it is an
essential variable in surveys where community water supplies are being planned but it is less
important for long-term monitoring.
Boron: boron is a natural component of freshwaters (surface- and groundwater) arising from the
weathering of rocks, soil leaching, volcanic action and other natural processes. Industries and
municipal wastewaters also contribute boron to surface waters. In addition, agricultural runoff
may contain boron, particularly in areas where it is used to improve crop yields or as a pesticide.
Boric acid, which does not readily dissociate, is the predominant species in freshwaters.
Cyanide: compounds of cyanide enter freshwaters with wastewaters from industries such as
electroplating. Cyanides occur in waters in ionic form or as weakly dissociated hydrocyanic acid.
In addition, they may occur as complex compounds with metals. The toxicity of cyanides
depends on their speciation; some ionic forms and hydrocyanic acid are highly toxic. The toxicity
of complex compounds of cyanide depends on their stability. Cyanide also exists in the soils and
groundwater near former gasworks.
Weak complexes formed with metals such as zinc, lead and cadmium are extremely toxic.
Copper complexes are less toxic, while cobalt and ferrous complexes are only weak toxicants.
Concentrations of cyanides in waters intended for human use, including complex forms, are
strictly limited because of their high toxicity.
6. Metals
Metals46 occur naturally and become integrated in aquatic organisms through food and
water. Trace metals such as mercury, copper, selenium and zinc are essential metabolic
components in low concentrations. Metals tend to bioaccumulate in tissues, however, and
prolonged exposure or exposure at higher concentrations can lead to illness. Elevated
45
http://www.igrac.net/publications/150
46
Verbatim, GEMS/Water 2008 p. 19
84
Planning of water-quality monitoring systems
concentrations of trace metals can have negative consequences for both wildlife and
humans. In particular, arsenic – a semi-metallic element which occurs naturally in some
surface- and groundwater sources – may lead to development of skin lesions and cancer in
people exposed to excess concentrations through drinking-water, bathing water or food.
Human activities such as mining and heavy industry can result in higher concentrations
than those that would be found naturally. As a result of acid mine drainage – outflow of acidic water from, among others, metal
mines – high concentrations of metals can be released into the environment.
Metals tend to be strongly associated with sediments in rivers, lakes and reservoirs and
their release to the surrounding water is largely a function of pH, oxidation-reduction state
and organic-matter content of the water (and the same is also true for nutrient and organic
compounds). Thus, WQM for metals should also examine sediment concentrations, so as
not to overlook a potential source of metal contamination to surface waters. The
assessment of metal pollution is an important aspect of most WQ assessment
programmes.
Regarding arsenic in groundwater47, the physicochemical conditions favouring arsenic
mobilization in aquifers are variable, complex and poorly understood, although some of
the key factors leading to high groundwater arsenic concentrations are known.
Mobilization can occur under strongly reducing conditions where arsenic, mainly as As(III),
is released by desorption from, and/or dissolution of, iron oxides. Immobilization under
reducing conditions is also possible. Some sulphate-reducing microorganisms can respire
As(V), leading to the formation of an As2S3 precipitate. Some immobilization of arsenic
may also occur if iron sulphides are formed.
7. Organic contaminants
Numerous hazardous substances deriving from the use of chemical substances are found
in the aquatic environment. The most widespread contamination of the aquatic
environment derives from pesticides and pesticide residues. Wastewater contains many
hazardous substances derived from detergents and other substances flushed into sewers.
In addition, many substances are used in industrial production and in the transport sector.
Numerous organic pollutants are found in groundwater, including pesticides and
substances leaching from contaminated sites (for example, petroleum of chlorinated
hydrocarbons). Pesticides also occur in watercourses. Concern is being expressed about
hormone-like substances which can change the sexual characteristics of fish species, such
as roach. In coastal waters, it has become apparent that hazardous substances, such as the
antifouling agent tributyltin, can affect marine organisms.
Personal care products such as soaps, shampoos and different types of cosmetics contain
substances that are not degraded in sewage-treatment systems and can therefore reach
the environment. Many substances are persistent, lipophilic (capable of combining with or
dissolving in fats) and bioaccumulating.
Triclosan is an antimicrobial active substance used for many purposes. such as
disinfectants, preservatives and personal care products. Triclosan is transformed to
methyltriclosan in the environment through a path which is not fully understood. This
substance persists in the environment and accumulates in organisms. Methyltriclosan
concentrations in fish are increasing at all sampling sites in Germany, but data about the
toxicity and action of methyltriclosan are largely missing.
47
http://www.igrac.net/publications/143
Annex 1. Description of the main water-quality variables
85
Many thousands of individual organic compounds enter water bodies as a result of human
activities. These compounds have significantly different physical, chemical and
toxicological properties. They are not monitored in all circumstances, however, because
their determination requires sophisticated instrumentation and highly trained personnel.
Much effort will be needed in monitoring these classes of compounds because they have
become widespread and have adverse effects on humans and the aquatic environment.
When selecting a list of variables for a survey of organic contaminants, the gross
parameters of TOC, COD and BOD should be included. In intensive surveys, the following
classes of organic pollutants should be identified: hydrocarbons (including aromatic and
polyaromatic), purgeable halocarbons, chlorinated hydrocarbons, different pesticide
groups, polychlorinated biphenyls (PCBs), phenols, phthalate esters, nitrosamines,
nitroaromatics, haloethers, benzidine derivatives and dioxins.
8. Biological variables
The biological elements for classification of the ecological status of waters could be
defined as follows:
•
Composition, abundance and biomass of phytoplankton;
•
Composition and abundance of other aquatic flora;
•
Composition and abundance of benthic invertebrate fauna;
•
Composition, abundance and age structure of fish fauna.
Groundwater-dependent ecosystems (GDE) are a diverse and important component of
biological diversity. The term GDE takes into account ecosystems that use groundwater as
part of survival and can potentially include wetlands, vegetation, mound springs, river
base flows, cave ecosystems, playa lakes and saline discharges, springs, mangroves, river
pools, billabongs and hanging swamps. The groundwater dependence of ecosystems will
range from complete reliance to those that partially rely on groundwater, such as during
droughts. The degree and nature of dependency will influence the extent to which
ecosystems are affected by changes to the groundwater system, both in quality and
quantity.
Phytoplankton: plankton algae are the most important group of primary producers in a
lake. As planktic algae have very short generation times, they also react rapidly to shifts in
the environment. Changes in the physical and/or chemical status of the water are traced
after some weeks through alterations of the species and their abundances.
The amount and the species composition of algal biomass are significantly dependent on
growth factors such as temperature and the concentrations of different nutrients. The
minimum nutrient in freshwaters in most natural lakes is usually phosphorus. The highest
density of algae can be found in the epilimnion.
In the classification of lakes, the phytoplankton is the most important factor, especially in
deeper lakes with clear stratification. Phytoplankton can also be used in local pollutioncontrol monitoring of recipient waters as an indicator of the toxic effects of sewage. In this
case, samples are not preserved. The aim is to investigate if phytoplankton are alive or
damaged by toxic substances.
Phytoplankton results can be used especially for assessment of the eutrophication status
of lakes.
Besides the total amount of phytoplankton, an important characteristic is the species
composition. Some species are typical in eutrophic waters, others indicate quite
86
Planning of water-quality monitoring systems
oligotrophic waters, etc. Several quotient systems based on phytoplankton species have
therefore been developed and are used in the assessment of lakes. They are usually most
suitable in smaller geographical areas – or even only in the same river basin.
Some algae species, however, are nearly always connected with eutrophy – the bluegreen algae. The mass occurrence of cyanophytes is always a signal of severe
eutrophication of a lake. These bloomings are usually found in late summer, when water
temperature is high. A massive water bloom is not only an ecologically inferior
phenomenon, it also has a negative impact on the use of water by restraining open-air
activities and by decreasing the production of fish for consumption. It also affects
drinking-water supplies.
Macrophytes : other biological quality elements for lakes are macrophytes and
phytobenthos. There are many characteristics of aquatic macrophytes, which can be used
as indicators in environmental monitoring. Due to local heterogeneity of habitats,
generalizations of indicator values are difficult, however, and variation in responses
should be interpreted carefully.
As the aquatic vegetation in a lake is influenced simultaneously by several factors,
macrophytes have only rarely a good indicative value when evaluating some specific
environmental variables. Instead, they give a good general estimation of the trophic state
of the site. Their use as indicators is further motivated by their relative persistence in the
site. Fluctuations in the population size of aquatic macrophytes are also usually minor in
comparison with many other organisms.
Periphyton: Periphyton is a complex community of microbiota (algae, bacteria, fungi,
animals, inorganic and organic detritus) that is attached to substrata. A distinct and
unpleasant sliming of underwater surfaces, e.g. stones, fishing nets and piers, is the most
visible nuisance effect caused by periphyton communities. Periphyton is often a major
primary producer in rivers but also in lakes with an extensive littoral area. Periphyton has
proved to be a good, useful indicator of WQ, responding to, and reflecting, conditions of
the immediate past.
The measurement of periphyton growth on artificial substrata has been widely used when
assessing the effect of point source loading (industrial effluents, municipal sewage
waters, etc.) on the primary production of the recipient surface waters.
The analyses usually determined from the quantitative periphyton samples are
chlorophyll-a content, fresh mass, dry mass, organic content and ash-free dry mass
(AFDM). Chlorophyll a describes the algal mass of the periphyton. This parameter is most
suitable for estimation of the eutrophication.
Benthic invertebrate fauna: benthic invertebrates (zoobenthos) have been increasingly
used in freshwater monitoring programmes. Due to its large species richness, covering all
types of freshwater habitats, and increased ecological knowledge of species’ response to
environmental conditions, zoobenthos can be used for different monitoring topics, such
as eutrophication, acidification, changes in habitat structure and species’ diversity and
toxicity. Zoobenthos is relatively easy to sample and, as sedentary and rather long-lived
organisms, they can reflect site-specific, long-term changes in nature.
Fish: fish are an important part of the biocoenosis in a lake. They have an important role
in the food web of the lake but, additionally, are the most interesting part of biocoenosis
for human consumption. It is quite natural, therefore, that fish faunae are also one of the
biological quality elements for use in ecological classification.
Fish are at the top of the food webs of the lake ecosystem and therefore have a strong
influence on other parts thereof. They feed on organisms belonging to other lower trophic
levels but, at the same time, are also food for other fish and invertebrates and, finally, for
birds and mammals, including human beings. Fish populations have also been found to
Annex 1. Description of the main water-quality variables
87
have significant effects on WQ. For example, dense fish populations may inhibit the
growth of phytoplankton and macrophytes through reducing the clarity of water.
At present, it is considered that the role of fish has changed and that fish populations are a
part of the ecosystem. In particular, the reason for this has been, besides the
implementation of the WFD, food-web manipulation for the purpose of WQ management.
Manipulation of food webs has proved to be a very useful tool in the improvement of
ecosystem health in lakes.
9. Microbiological indicators
The most common risk to human health associated with water stems from the presence of
microorganisms. Microorganisms capable of causing disease in humans and animals are
introduced into lake water in treated wastewater, runoff, contaminated brook and river
water entering the lake and, occasionally, directly in animal droppings. Infectious agents
are various bacteria, viruses and protozoa, together with other parasites. Today, it is not
possible to monitor the occurrence of every pathogen possibly present in lake water. The
main concerns are those pathogens transmitted through faeces and capable of causing
epidemics via contaminated water.
The enumeration of bacteria normally occurring in high numbers in the faeces of humans
and homoeothermic animals has been successfully used for more than a century for the
detection of faecal contamination. This strategy has been of immense importance in
protecting humans against infectious diseases transmitted via water that cause extensive
epidemics through contaminated drinking-water and also contaminated water which is
used for irrigation and recreational purposes.
When planning sampling programmes, it is important to assess the possible
contamination sources and their temporal and spatial impacts. Pipelines conducting
treated wastewater should be located and, ideally, the volume and quality of wastewater
noted. Pipes bringing non-treated domestic wastewater and water from animal husbandry
should be identified. Possible leakages in pipes causing groundwater contamination
should also be taken into account. Pastures adjacent to lakeshores are probable sources of
faecal contamination, especially during runoff episodes. Flocks of birds are known sources
of direct contamination of lake water. Naturally, the hygienic state of a lake is affected by
the hygienic quality of river and brook water entering it. Usually, surface water is most
vulnerable to contamination, but the introduction or infiltration of wastewater to deeper
water layers or re-suspension of sediment may also cause heavy contamination of
subsurface- and groundwater.
10. Sedimentation
Sediment transport48 into aquatic systems results from almost all human land use and
industrial activities, including agriculture, forestry, urbanization and mining. Increases in
sediment transport to aquatic systems are typically observed as bank-side vegetation is
degraded or removed, rivers are canalized to enable development closer to stream-banks,
and natural land cover is removed or replaced by human-built land cover (e.g. roads and
buildings). The construction of impoundments also generates sediments and alters the
natural sedimentation regime of many watercourses: sediments tend to accumulate in
reservoirs and ecosystems downstream of reservoirs are often depleted of their natural
sediment fluxes and riverbank scouring is increased.
48
Verbatim from GEMS/Water, 2008, 35-36
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Planning of water-quality monitoring systems
The transport of sediments into surface waters has both physical and chemical
consequences for WQ and aquatic ecosystem health. High turbidity can decrease the
amount of available sunlight, limiting the production of algae and macrophytes. Fish
habitats can be degraded as spawning gravel becomes filled with fine particles, restricting
the oxygen available for buried eggs. Turbid waters may also damage fish directly by
irritating or scouring their gills or by reducing the success of visual predators. The
scouring action of turbid waters may also harm some benthic macroinvertebrates.
Very fine sediment (less than 63 μm) is often chemically active. Phosphorus and metals
tend to be highly attracted to the ionic exchange sites associated with iron and manganese
coatings that occur on small particles. Many toxic organic contaminants, such as
pesticides or their breakdown products, are strongly associated with silt, clay and organic
carbon transported by rivers. Thus, sediments act as an agent in the process of
eutrophication and toxicity in aquatic organisms. High sediment loads in surface waters
can also increase thermal pollution by increasing the absorption of light, thereby
increasing water temperatures. Finally, high-sediment loads can impair navigation and
water-retention facilities by silting in watercourses and filling in reservoirs, thereby
necessitating costly dredging or shortening their useful life. The dredging of reservoirs,
watercourses, harbours and lakes also has serious implications for the ecology of these
systems.
Due to dredging, toxic chemicals (heavy metals or PCBs) can be released from bottom
sediments to the water column.
Annex 2. Description of main water-quality monitoring methods and
techniques
1. WQ monitoring equipment
In situ and portable WQM devices are often used as there is an increasing need to
monitor large areas in short time intervals. The benefits associated with this type of
technology include:
•
Rapid results that can be sent immediately;
•
Continuous monitoring;
•
Automatic monitoring;
•
Short-term management;
•
Monitoring of decontamination processes;
•
Early warning systems and applications;
•
Reduction in error associated with sample preparation, transport and storage.
The development of novel, accurate and precise tests for the detection of
physicochemical properties, biological conditions or pollutants in water has been rapid
in the past decade, as new technologies have become available. One of the promising
advances is a multi-parameter optical analyser based on lab-on-a-chip technology
measuring up to 24 different physicochemical results in just a few minutes. Other recent
technologies used for physicochemical detection include different kinds of
immunoassays. Developing technologies for measuring microbial contaminants of
waters include:
•
New enzyme/substrate methods that incorporate high-sensitivity fluorescence
detection instruments, including dual wavelength fluorometry simultaneously to
assess both enzymatic hydrolysis and the loss of substrate;
•
Quantitative polymerase chain reaction technology that relies on specific nucleic
acid sequences, and antibody-antigen binding properties, which include evanescent
wave fibre-optic biosensors;
•
The rapid bacteria detection system, which is based on laser flow-through
technology and capture of the antigen by antibodies on magnetic beads.
2. Optical monitoring
Optical absorption measurements – spectrophotometry – are used for measuring a range
of analytes in aquatic environments, such as humic substances. Spectrophotometric
sensors have the potential to offer superior stability and precision to electrode devices.
Nutrients in water can be measured directly using UV absorption. The use of UV
absorption for characterizing nitrates and other compounds in wastewater has been
examined in several publications. Optodes for DO measurement are at an advanced
stage of development. They have the advantages of simple construction, no analyte
consumption, less sensitivity to fouling and good stability. A number of commercial
instruments exist for chlorophyll measurement, using excitation in the UV (blue) and
emission in the blue (red) parts of the spectrum (fluorometry).
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Planning of water-quality monitoring systems
The dependence of the refractive index of seawater on salinity is well known, including its
temperature and pressure sensitivity. A fibre-optic refractive-index sensor based on
surface-plasmon resonance has been developed for the purpose of salinity measurement.
This kind of device has shown good sensitivity and correlation with a more traditional
commercial conductivity-temperature-depth probe.
Another form of absorption spectroscopy is attenuated total reflection. Chlorinated
hydrocarbons have been measured using this method. Optical backscatter can be used
to measure suspended solids and turbidity. This has been used, for example, to
measure phytoplankton production and total suspended matter concentrations.
Some optical instruments use thermal light sources, which could be made more compact,
reliable and stable using light-emitting diodes (LEDs). Furthermore, the ever-expanding
range of LEDs, at both ends of the optical spectrum, open up opportunities for new sensing
techniques. LEDs are now available below 250 nm and up to 7 μm, with narrow enough
bandwidths to avoid adjacent (e.g. H2O) absorption bands. Additionally, tunable laser diodes
allow fine spectral discrimination of, for example, narrow absorption lines. Another attractive
technology is compact spectrometers, allowing nanometre spectral resolution in little more
than the size of a matchbox. Fibre-optic sensors offer compactness, stability and high
sensitivity and allow distributed measurements to be made.
Low-cost video/imaging technology applied to water bodies is a nascent field – opportunities
exist for measuring flow and biota, for example. The latter would require image-processing
techniques for recognizing and counting and could also be coupled with spectral
information. Biofouling is a significant issue for optical sensors: some of the existing
techniques are effective but there is scope for further work in this area. Simple techniques
using standard digital cameras for water colour or transparency are also under development.
Different kinds of flow-through systems and profiling instruments using optical sensing
(absorption, attenuation, fluorescence of light) have been developed for rapid monitoring of
chlorophyll, suspended matter and humic substances. In conclusion: rapid developments in
optical methods offer excellent solutions for better spatial resolution of sampling and costeffective monitoring.
3. Simple field-measured variables
Temperature: temperature should be measured in situ, using a thermometer or thermistor.
Some meters designed to measure oxygen or conductivity can also measure temperature.
As temperature has an influence on so many other aquatic variables and processes, it is
important always to include it in a sampling regime and to take and record it at the time of
collecting water samples. For a detailed understanding of biological and chemical processes
in water bodies, it is often necessary to take a series of temperature measurements
throughout the depth of the water, particularly during periods of temperature stratification in
lakes and reservoirs. There are also gauges for measuring water temperature in monitoring
wells.
pH measurement: pH is a measure of the acidity or alkalinity of a solution. Neutral solutions
have a pH of 7, acid solutions a pH of less than 7 and alkaline solutions a pH greater than 7.
The pH should be determined in the field, immediately after sample collection. Many
portable pH meters are on the market today; investigators should select the one that best
suits their needs.
Conductivity measurement: conductivity (specific conductance) is a numerical expression
of water’s ability to conduct an electric current. Conductivity depends on the concentration
of ions in solution and in situ measurements are preferable. Conductivity is temperaturedependent: if the conductivity measurement is not automatically temperature-corrected,
then the temperature at the time of measurement should also be recorded. Various
Annex 2. Description of main water-quality monitoring methods and techniques
91
conductivity meters are available which may also have temperature- and salinitydetermining capabilities.
Oxygen measurement: DO should be measured in situ or in the field, as concentrations may
show a large change in a short time if the sample is not adequately preserved. Even when it
is preserved, as in a Winkler analysis, it is advisable to run the titrations within three to six
hours from the time the sample was taken. DO concentrations may be determined directly
with a DO meter, optode or by a chemical method such as Winkler analysis or the Hach
method. The method chosen will depend on a number of factors, including the accuracy and
precision required, convenience, equipment and personnel available and expected
interferences. For very precise measurements, the potentiometric method should be
considered.
The samples for oxygen determinations are always taken as a vertical series starting from
the uppermost layer in the epilimnion (usually one metre) and finishing in the hypolimnion at
a depth that is one metre above the bottom sediment.
Turbidity and transparency: this is an optical measure of suspended sediment such as clay,
silt, organic matter, plankton and microscopic organisms in a water sample. Whenever
possible, turbidity should be measured in-field, since some of the particulate matter will
settle or adhere to the container wall during transportation. Furthermore, changes in the pH
of the sample may cause the precipitation of carbonates and humic acids, affecting the
turbidity of the sample. Turbidity can be measured with turbidity meters that measure
light-scattering by the suspended particles.
Although optical devices are available for measuring the intensity of solar radiation at depth
in the water column, the simple procedure of determining transparency with a Secchi disc
still retains its value. The method is to observe the depth at which a 30-cm-diameter disc,
painted white or with black and white quadrants, disappears from view as it is lowered in the
water column. The actual procedure is to record the point of disappearance as the disc is
lowered, allow it to drop a little farther and then determine the point of re-emergence as the
disc is raised. The mean of the two readings is known as the Secchi disc transparency.
4. Other important parameters that can be measured in situ
Total suspended solids: suspended particles affect water clarity and light penetration,
temperature, the dissolved constituents of surface water, the adsorption of toxic
substances, such as organics and heavy metals, and the composition, distribution and rate
of sedimentation of matter. Waters high in suspended solids may be aesthetically
unsatisfactory for recreational activities. Analyses of solids are important in the control of
biological and physical wastewater-treatment processes and for assessing compliance with
guidelines imposed by regulatory agencies for wastewater effluents.
TSS is a measure of the material collected on a glass fibre filter ( :0.45 μm and dried to a
constant weight at 103°C–105°C. If the suspended matter clogs the filter and prolongs
filtration, the weight difference between the total solids content (also dried at 103°C–105°C)
and the total dissolved solids (filtrate dried to constant weight at 180°C) may be used to
estimate the TSS. TSS can also be determined, using optical instruments (backscattering of
light).
Chlorophyll: chlorophyll fluoresces red when excited by blue light and this property can be
used to measure chlorophyll levels and indicate algal biomass. Direct and continuous
measurement of chlorophyll fluorescence can be made with a fluorometer, which can be
used in situ by pumping water through it or, for some specially designed instruments, by
lowering it into the water. Chlorophyll can also be determined in situ by optical spectral
instruments, using the reflectance spectra, and naturally from water samples in a
laboratory.
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Planning of water-quality monitoring systems
Carbon: The principle of all methods for the determination of total carbon (TC) in water is
oxidation of the carbon to CO2. Oxidation may be carried out by combustion, chemical
reaction by the wet method using appropriate oxidizing agents, UV irradiation or any other
appropriate procedure. The CO2 formed may be determined directly or indirectly following
reduction to another component (methane, for example).
Various analytical methods have been suggested, some of which are:
•
•
•
•
•
•
•
Infra-red spectrometry;
Volumetric determination;
Thermal conductivity;
Conductimetric measurement;
Coulometric measurement;
Specific CO2 electrode;
Flame ionization, following methanization.
A water sample may contain variable amounts of dissolved and particulate organic
carbon, organic carbon originating from more or less volatile substances and
dissolved mineral carbon (carbonates, carbon dioxide) and particulate carbon (active
charcoal). The different matrices of the specimens that result from the presence of
these forms of carbon in variable proportions must be taken into consideration before
the analysis, because they largely determine what apparatus and procedure to select.
Total fulvic and humic acid content can be determined photometrically and their
separate determination can be made with spectrophotometric methods.
Alkalinity : alkalinity is measured commonly by titration, using either a burette or the
drop-count technique. A sample is titrated with an acid solution which neutralizes the
alkaline species present. The endpoint is determined by observing a colour change or
by titrating to a pH value of 4.5, using a pH electrode as an indicator. The volume of
titrant required to change the colour to reach the endpoint is then used to calculate
total alkalinity. Both methods have limitations: sample colour or turbidity affects the
operator’s ability to detect the colour change; use of a burette or dropper is tedious
and time-consuming. Total alkalinity test kits, which simplify routine alkalinity
measurement, are ideal for field use.
Nutrients : the measurement of nutrients (phosphates, nitrates) is a significant and
widespread requirement that is currently met mostly by water-sampling or the
deployment of expensive wet-chemical water analysers but there are also rapid
developments in less expensive methods. Remote spectral sensing can be used to
obtain information about large-scale distributions of nutrients in surface water but
direct measurement methods are required for measurements on smaller scales (e.g. in
creeks, rivers, wastewater, outfalls, etc.) for QA and evaluation of the remote-sensing
data and for more accurate measurements. Optical spectral sensing techniques have
been developed recently that provide reagent-free measurement of nutrients using UV
absorption spectrophotometry.
In situ nutrient analysers are available for high-frequency time-series determination of
nutrient concentrations in marine and freshwaters. Versions are available for the
measurement of nitrate, phosphate, silicate and ammonia. Some analysers may be
deployed unattended for periods of one to three months, although much longer
deployments have been achieved.
Microbiological indicators : there is a strong need for the detection of pathogens,
on-site and effectively in real-time (the “lab-to-sample” approach), to avoid the costs
and delays associated with water-sampling and laboratory analysis. There is
considerable interest in the development of toxicity sensing to overcome the problems
associated with identification of individual target species from a large number of
possibilities.
Annex 2. Description of main water-quality monitoring methods and techniques
93
There are rapid screening technologies, from which results may be obtained within
hours and there is an obvious push towards desktop and portable systems. They can
detect, for example, the normal intestinal bacterium Escherichia coli as an “indicator”
organism and total coliform bacteria for a wide variety of water-testing applications. In
addition, the following bioagents may be detected: clostridium botulinum neurotoxin,
staphylococcal enterotoxins (A and B), bacillus anthracis, yersinia pestis and also cholera
toxin sub-units and tetanus toxin.
Methods for detecting the presence of faecal material have been developed which are
based on the presence of “indicator” organisms, such as E-coli. Such methods are cheap
and simple to perform and some have been developed into field kits, particularly for use
in developing countries.
Metals : the low concentrations of metals in natural waters require determination by
instrumental methods. Photometric methods, sometimes in combination with extraction,
are the oldest and most inexpensive techniques (see various methods handbooks).
Potentiometric methods, employing ion-selective electrodes, are also available for
various methods for monitoring different metals in the field.
As these have high detection limits, however, they can only be used for the analysis of
comparatively polluted waters. Atomic absorption methods are the most widely used for
detecting lower levels of metals.
Inductively coupled plasma-mass spectrometry (ICP-MS) or inductively coupled plasmaoptical emission spectroscopy (ICP-OES) are highly sensitive techniques that are capable
of determining a range of metals and several non-metals.
5. Traditional water-sampling for laboratory chemical and biological analysis
The collection of water samples may seem a relatively simple task. More than the simple
dipping of a container into water or the pumping of groundwater from the well is
required, however, to obtain representative water samples and to preserve their integrity
until they are analysed in the laboratory. The quality of the data collected depends first
and foremost on how good the sample is, i.e. how well it represents the quality of the
body of water from which it was collected and whether or not contamination has been
avoided. Using the most reliable techniques for collecting samples and making field
measurements contributes to the good quality of the data, increases their precision and
accuracy and contributes to the overall improvement of the WQ management process.
Collecting surface water samples : the type of surface-water sample to be collected is
determined by a number of factors such as:
•
The objectives of the study, including the parameters of interest and the precision
and accuracy needed;
•
The characteristics of the system being studied, including the flow regime, climatic
conditions, industrial inputs, groundwater infusions, tributaries, the homogeneity of
the body of water and the aquatic life present;
•
The resources available, i.e. manpower, equipment and materials.
It is recommended that the design of the field-sampling programme be tested and
assessed by a pilot projector in the initial rounds of sampling to ensure both its
effectiveness and efficiency with respect to the objectives of the study.
Groundwater samples : these samples can be collected from wells and springs.
Depending on the purpose of the monitoring, the depth or the resources available,
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Planning of water-quality monitoring systems
automatic sampling and analysis can be done in situ by using water-quality sensors,
thus avoiding atmospheric contamination of the groundwater sample.
G rab samples : a “discrete” grab (or spot) sample is one that is taken at a selected
location, depth and time, and then analysed for the constituents of interest.
A “depth-integrated” grab sample is collected over a predetermined part or the entire
depth of the water column at a selected location and time in a given body of water and
then analysed for the constituents of interest.
The collection of grab samples is appropriate when it is desired to:
•
Characterize WQ at a particular time and location;
•
Provide information about minima and maxima;
•
Allow collection of variable sample volumes;
•
Deal with a stream which does not flow continuously;
•
Analyse parameters which are likely to change;
•
Establish the history of WQ, based on relatively short time intervals.
Grab samplers may be divided into two broad categories: those appropriate for taking
samples in which only non-volatile constituents are of concern and those for taking
samples in which dissolved gases and other volatile constituents must be analysed.
No simple technique is available for obtaining a representative sample of a surface
film such as oil or grease. A grab sample can be taken with a solvent-cleaned glass
bottle opened just below the surface but the sample will only be qualitative. A grab
sample may be taken, using a “sampling iron” with an appropriate bottle, a Van Dorn
bottle, a Kemmerer-style bottle or a pump-type sampler.
Composite samples : a composite sample is obtained by mixing several discrete
samples of equal or weighted volumes in one container, an aliquot of which is then
analysed for the constituents of interest or by continuously sampling the flow. There
are two main types of composite sample:
•
Sequential or time composite made up by:
- Continuous constant sample pumping; or
- Mixing equal water volumes collected at regular time intervals.
•
Flow-proportional composite obtained by:
- Continuous pumping at a rate proportional to the flow;
- Mixing equal volumes of water collected at time intervals, which are inversely
proportional to the volume of flow; or
- Mixing volumes of water proportional to the flow collected during or at regular
time intervals.
A composite sample provides an estimate of average WQ condition over the period of
sampling. An obvious advantage is in the economy of reducing the number of samples
to be analysed. On the other hand, composite samples cannot detect changes in
parameters occurring during the sampling period.
Annex 2. Description of main water-quality monitoring methods and techniques
95
For water-quality sampling sites located on a homogeneous reach of a river or stream, the
collection of depth-integrated samples in a single vertical may be adequate. For small
streams, a grab sample taken at the centroid of flow is usually adequate.
For sampling sites located on a non-homogeneous reach of a river or stream, it is
necessary to sample the channel cross-section at the location at a specified number of
points and depths. The number and type of samples taken will depend on the width, depth,
discharge, the amount of suspended sediment being transported and the aquatic life
present. One common method is the equal-width increment (EWI) method, in which
verticals are spaced at equal intervals across the stream. The equal-discharge increment
(EDI) method requires detailed knowledge of the streamflow distribution in the crosssection in order to subdivide the cross-section into verticals proportional to incremental
discharges.
Automatic samplers : these range from elaborate instruments with flexible sampling
programmes, requiring external power and permanent housing to simple, portable, selfcontained devices such as a submerged bottle whose rate of filling is determined by a slow
air bleed.
These devices can sometimes be programmed to sample over extended periods of time.
They reduce costly personnel requirements, if frequent sampling is required. If the site has
automatic flow measurement, they can also provide flow-proportional samples. Both
composite and individual sample models are available. Regular maintenance and
scrupulous cleanliness are essential if the samples are to be representative. It is difficult to
obtain representative samples of suspended solids because of gas release on pumping,
which may also be a problem in sampling for dissolved gases.
6. Special sampling procedures
Rivers : sampling difficulties arise when the only acceptable sampling point lies in a
non-homogenous – i.e. unmixed – length of a river. Individual samples will then not be
representative of the water body. It will be necessary to sample over a cross-section of the
river to obtain average values and this can be done in a number of ways.
The river is considered in terms of a series of vertical sections across the chosen site.
Discrete samples are taken in each section and analysed separately. The results for each
may then be averaged by adding them together and dividing by the number of samples.
Alternatively, to save analytical work, the samples may be mixed in equal proportions and
the analyses of the composite will be the same as the calculated values. This average will
be time-weighted and will ignore the differences in flow between the sections.
It is preferable to obtain flow-weighted averages and this involves measuring the volume
of flow in each section at the time of sampling. The cross-sectional area of each section
must be known and velocity profiles for each prepared. The flow in each section is
multiplied by the value of the sector, the results for all sectors added and the result divided
by the total flow to give the flow-weighted average. Again, analytical work can be reduced
by preparing a composite sample containing sectional samples added in proportion to the
sectional flows – a time-consuming process, however.
If a series of flow-weighted averages are taken, using analyses of individual samples, it
may prove possible to derive a mathematical relationship between the analytical results at
one, or perhaps a few, sampling points and the flow-weighted average. The use of such a
relationship would greatly reduce the time and labour involved but the reliability of the
result is likely to be somewhat lower.
Lakes : many lakes exhibit seasonal thermal stratification. When stratification exists, a
number of samples will be taken vertically, according to the position of the metalimnion or
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Planning of water-quality monitoring systems
thermocline. A vertical profile of the stratification may be plotted from a series of vertical
temperature measurements. Samples should be taken:
1. Immediately below the water surface;
2. Immediately above the epilimnion;
3. Immediately below the epilimnion;
4. Mid-hypolimnion;
5. One metre above the sediment/water interface.
If there is an anoxic zone, it is desirable to take at least two samples in this layer. For
deep lakes, additional samples at, say, 100-m intervals should be taken. When the lake
is fully mixed, samples should be taken at least at points 1 and 5 above. If, after
turnover, there is still an anoxic zone lying on the bottom, this should also be sampled
in the neighbourhood of its upper boundary layer.
Groundwater : such samples will normally be taken at existing wells or boreholes. The
water should be pumped for some time before sampling to ensure that new water is
taken. The water emerging at the surface is often a mixture of waters derived from
different strata. This is not of great importance, provided the relative contributions
from each stratum are fairly constant. If information is required about the quality from
the different strata, it may be possible to lower a tube or tubes down the borehole and
abstract at different levels. Probes to measure conductivity and other variables may
be lowered into the well and their profile plotted.
As the groundwater has usually been out of contact with air for a considerable period,
dissolved gases may not be in equilibrium with the atmosphere and the emerging
water may change its character quite rapidly. Dissolved CO 2 may be lost to the
atmosphere and cause changes in the pH value of the water. If the water is anoxic,
oxygen will be taken up and oxidized iron and manganese precipitated. The samples
need to be taken out of contact with air and a bleed pipe from the pump delivery
should pass into the sample bottles, which should be left to overflow before sealing.
As far as possible, the analyses should be carried out on site.
7. Biological assessment and fish tests
One of the oldest biological research methods of WQ is the examination of the biomass
and composition of phytoplankton by microscopy. The considerable advantage of this
method is that important information on species composition and dominant species is
simultaneously achieved.
A good characteristic is the total volume (or total wet weight) of phytoplankton estimated
by microscopy. Many classifications based on total amount have been presented. An
indirect but practical method to obtain a relatively reliable estimation of the phytoplankton
quantity is chemical chlorophyll analysis. These two characteristics are significantly
correlated with each other. Different classifications have therefore been established, based
on chlorophyll-a concentrations, which can also be determined by in situ optical methods.
Macroinvertebrates are the most commonly used group of organisms in biological
monitoring in industrialized countries. In China, for example, biological assessment of
water pollution in rivers and aquatic ecosystems has been carried out successfully with the
use of plankton, benthos and fish as indicators. Algae are often selected as indicators of
eutrophication and increases in turbidity. Bacteria are useful indicators for a range of
pollutants and faecal coliform. They respond quickly to environmental changes.
Annex 2. Description of main water-quality monitoring methods and techniques
97
It is crucial to appreciate that ecosystems function as one entity in which feedback
mechanisms regulate the stability between the various trophic levels: primary producers,
decomposers, herbivores, etc. Natural fluctuations or point-pollution discharges can be
considered at an ecosystem level. An impact at any trophic level is felt at every point
within the food web and, if severe, leads to an imbalance in the entire ecosystem.
Biodiversity studies are important for achieving an overall picture of the state of the
ecosystem.
The choice of indicator must be carefully considered, as there is a wide range of
sensitivities between organisms to stimuli and chemicals. Moreover, in view of the large
number of samples required to obtain reliable results and the associated cost, it is
advisable to limit the number of assays to only a few important species to ensure
availability of funds for a satisfactory monitoring of temporal trends of some priority
contaminants over time.
Sampling for microbiological analysis : the selection of microbiological parameters for
monitoring depends on the aim. If this is to follow the level of faecal contamination in the
lake or river water, enumeration of indicators of faecal contamination shall be monitored. If
the identification of actual health risks is of concern, then pathogen detection is needed. In
the selection of parameters, it is necessary to consider geographical, socio-economic and
technological aspects. It is reasonable to set minimum requirements for the monitoring
and to allow additional parameters to be selected on the basis of local circumstances.
Today, it is not possible to monitor the occurrence of every pathogen possibly present in
lake or river water. The pathogens transmitted through faeces and capable of causing
epidemics via contaminated water are the main concern. Direct, routine monitoring for the
detection of these pathogens is still difficult but the rapid developments in molecular
methods (e.g. microarrays or DNA chips) may, in the future, offer powerful methods for the
direct monitoring of different pathogens simultaneously. The main emphasis in the
protection of WQ and human health will, however, be on the restriction of faecal
contamination.
Positive identification of the pathogenic bacteria Salmonella, Shigella or Vibrio spp. can be
quite complex, requiring several different measurement methods. A special survey may be
undertaken if a source of an epidemic is suspected or if a new drinking-water supply is
being tested. As these organisms usually occur in very low numbers in water samples, it is
necessary to concentrate the samples by a filtration technique prior to the analysis.
Although methodologies for identification of viruses are constantly being improved and
simplified, they require advanced and expensive laboratory facilities. Local or regional
authorities responsible for WQ may be unable to provide such facilities. Suitably collected
and prepared samples can easily be transported, however, making it feasible to have one
national or regional laboratory capable of such analyses.
8. Kits
Partly due to resource and time constraints to establish well-equipped WQ testing
laboratories in sufficient numbers, and partly due to the dynamic nature of water quality,
there is a definite place for simplified field-test kits in an overall approach to WQM, especially
in developing countries. Kits can accomplish the initial screening and periodical monitoring
of waters. Such tests are relatively inexpensive and can be conducted at water-user level,
thereby improving the potential for involvement of user communities. Results of kits can be
supported by detailed analysis of problem sources in proper laboratories.
Several companies/agencies/NGOs/government laboratories have done a lot of work to
produce kits which use titration principles but are light, can stand up to rough “travel”
and still give fairly accurate results. These field test kits can be used anywhere and by
anyone who can read the instructions. They consist of a sample bottle with a marking
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Planning of water-quality monitoring systems
to indicate that the sample to be tested must be filled up to that mark. When the colour
of the sample changes, the addition of the solution is stopped and the number of
drops added is multiplied by a factor given in the instruction manual to arrive at the
quantity of the parameter in mg/litre of water or parts per million.
Test kits used for testing the bacteriological content in water are slightly different. Some have a
bottle in which the water sample to be tested is put and into which another solution is added.
Another kit used for such tests is called a “dipslide”: a slide made of an inert plastic material,
coated with a nutrient kept inside a sealed container. Used in conjunction with an incubator, it
avoids the need for lengthy laboratory-based procedures. Dipslides can be used to monitor
microbial growth wherever the potential may exceed 1 000 organisms per millilitre of sample
fluid. Tests for bacteriological contamination using such kits indicate only the presence or absence
of contamination (also called a GO/NO GO result) and not its extent. UNICEF has also developed
a simple kit using the H2S strip test, which is intended to detect or quantify hydrogen-sulphideproducing bacteria, considered to be associated with faecal or bacterial contamination.
In conclusion, there are field kits (discs, test strips, drop-test kits, dipslides) that allow
qualitative testing for E-coli and bacterial contamination in general, DO, pH, electrical
conductivity, temperature difference, turbidity and level of nitrite, nitrate and
orthophosphate ions, arsenic, fluoride, iron, residual chlorine, chloride, alkalinity,
hardness and aluminium and arsenic.
Using small samples (5-10 ml), these kits allow quick qualitative testing and recording
of results anywhere. Results are taken by comparison with a colour chart if the sample
turns a colour and are qualitative. The kits are useful for general water-testing. A
choice can be made from a range of equipment and parameters to use individually or
combine into a single test kit.
9. Remote-sensing (satellite, airborne or ground-based)
There are some unique challenges to the application of remote-sensing to WQ in inland
and coastal regions:
•
These waters are a complex mixture of constituents, the composition of which
varies across water bodies, regions and globally. Unlike blue open-ocean surface
waters, which are generally clear and typically contain only low concentrations of
phytoplankton, inland and coastal waters contain a myriad of both dissolved and
particulate matter reflected in their blue-green to green and brown colours;
•
Inland and coastal waters may exhibit heterogeneous patterns of water quality.
These patterns and associated processes and phenomena are dynamic, shortlived and small-scale and may be missed by satellites with inadequate spatial
and/or temporal observing capabilities;
•
Small water bodies (lakes) are irregularly distributed across the terrestrial
landscape, often representing only a few pixels in a satellite image and
confounded by a number of “edge” pixels;
•
Remote-sensing generally only represents surface conditions down to the depth
at which a white and black coloured (Secchi) disc can be seen;
•
A translation is required from the observed colour in visible and nearby infra-red
wavelengths to those WQ relevant properties primarily of interest to a manager
or decision-maker (e.g. bacteria or eutrophication status).
Knowledge of the spatial distribution of different biological, chemical and physical
variables is essential in environmental water studies, as well as for resource management.
Coupled with advanced processing methods and improved sensor capabilities, recent
Annex 2. Description of main water-quality monitoring methods and techniques
99
years have therefore seen increasing interest and research in the remote-sensing of the
quality of inland and coastal waters. Unless a water body is sufficiently instrumented by in
situ sensors, remote-sensing is the only satisfactory method for detecting the quality of
remote and large inland waters.
Waters, whose optical properties are influenced by more than just phytoplankton, are
determined to be complex waters (unlike ocean waters). These additional non-algal optical
properties may be composed of dissolved organic matter, dead particulate organic matter
and particulate inorganic matter. The source can be allochthonous (via inflow from
surrounding land) or autochthonous (produced within the water body by biological or
chemical interactions). Many inland and coastal waters are significantly affected by
anthropogenic influences such as nutrient enrichment or increased erosion-induced
suspended material. In combination with the sometimes complex hydrological situation,
highly contrasted structures evolve in time and space in these aquatic environments. It is
obvious that a water system with different optically active substances with temporal and
spatial variations is more complex and therefore requires more sophisticated analysis
models for remote-sensing-based separation of the water constituents than the single
optical component ocean waters. As many spectral bands as possible are therefore
required across the visible and nearby infra-red spectrum, where light penetrates the water
column. This is the reason for multispectral remote-sensing and, if available, imaging
spectrometry is applied to coastal and inland water environments instead of a few bands
in the blue-to-green spectral areas.
The colour of the water is caused by light-scattering and absorption processes, as well as
light emission by substances in the water column and reflectance by the substrate
(seagrass, macroalgae, corals, sand, mud, benthic microalgae, etc.). For the retrieval of
different water constituents, as well as substrate type or cover from a remotely sensed
multi- or hyperspectral signal within a remote-sensing image, a suite of inversion methods
is available, ranging from the often used, but less precise regression methods, to physicsbased inverse modelling or inversion methods. The water-colour data can be used to
determine the concentrations of the water constituents and the substrate cover
quantitatively. The range of optical WQ properties measurable in the water column that
may be estimated by remote-sensing has increased from suspended matter to include
properties such as vertical attenuation coefficients of downwelling and upwelling light,
transparency, coloured dissolved organic matter, chlorophyll-a contents, blue-green algal
pigments and even red tides and blue-green algal blooms. If the water column is
sufficiently transparent, it has been demonstrated that maps may be made of seagrasses,
macroalgae, sand and sandbanks, coral reefs, etc. Other applications and parameters are
water clarity, macrophyte surveys, slick and spill detection and underlying geophysical
parameters, such as surface temperature, winds, currents and waves, bathymetry and
flood area.
Correct simulations of the reflectance spectrum (colour) from waters and suitable
inversion methods drastically reduce the requirement for traditional in situ measurements
in the long term. As in situ detection and monitoring become more expensive (due to
rising labour costs) and is shown to be less exact, a remote-sensing based approach is
beginning to make more and more economic sense. It will be necessary to have available
local airborne multi- or imaging-spectrometry systems or similar types of data from space
sensors. Imaging spectrometry seems to be the remote-sensing instrument of choice for
the future for the accurate detection and monitoring of optical WQ and substrate variables.
The increased sophistication and automation of in situ sensors, however, may prove to be
a bonus for remote-sensing, as an integrated, automated in situ sensor with a dedicated,
remote-sensing monitoring system could provide continuous data, even under unsuitable
conditions.
Some countries and institutions have developed new operational products using satellite
remote-sensing, such as the operational satellite-based WQ products of the Finnish
Environment Institute. These are the surface-water temperature of the Baltic Sea and large
lakes and surface algal blooms, turbidity and chlorophyll a of the northern Baltic Sea. The
100
Planning of water-quality monitoring systems
satellite images used are from NASA/Landsat, NOAA/AVHRR, Terra/MODIS and ENVISAT/
MERIS and the operational products are available on their Websites. The use of satellite
images requires reference measurements at the monitoring stations for algorithm
calibration and validation. Remote-sensing includes also ground-based teledetection,
which permits the characterization of the spatial and temporal changes obtainable by in
situ methods.
Finally, some of the world’s most advanced remote-sensing laboratories are now
developing remote-sensing-based data-assimilation methods, where biogeochemical
models, hydrodynamic models, in situ sensor data and quantitative remote-sensing
methods are being integrated to provide hindcasting, nowcasting and forecasting of water
quality.
10. Advanced instrumental analysis
Atomic absorption spectrophotometry (AAS ): AAS is commonly used in many analytical
laboratories for determining trace elements in water samples and in acid digests of
sediment or biological tissues.
AAS is based on the principle that metallic elements in the ground state will absorb light of
the same wavelength that they emit when excited. When radiation from a given excited
element is passed through a flame containing ground-state atoms of that element, the
intensity of the transmitted radiation will decrease in proportion to the amount of groundstate elements in the flame. The lamps used to furnish the light beam are called hollow
cathode lamps and are made of, or lined with, the element of interest and filled with an
inert gas, generally neon or argon. When subjected to a current, these lamps emit the
spectrum of the desired element, together with that of the filler gas. The metal atoms to be
quantified are placed in the beam-of-light radiation by aspirating the sample into a flame.
The element of interest in the sample is not excited by the influence of the flame, but
merely dissociated from its chemical bonds and placed in an unexcited, unionized
“ground” state. The element is then capable of absorbing radiation from the light source.
The amount of radiation absorbed in the flame is proportional to the concentration of the
element present. While the simplest analysis procedure is direct aspiration of a liquid
sample into the atomizer-burner assembly, there may be limitations of detectability or
interferences that make further sample processing necessary to increase concentration or
isolate the element of interest from interfering species.
As already mentioned under the section on metals above, ICP-MS or ICP-OES are
techniques that are highly sensitive and capable of determining a range of metals and
several non-metals.
Gas chromatography: this is a highly sophisticated, analytical procedure. It should be used
only by analysts who are experienced in the techniques required and competent to
evaluate and interpret the data.
In gas chromatography, a carrier phase (a carrier gas) and a stationary phase (columnpacking or capillary column-coating) are used to separate individual compounds. The
carrier gas is nitrogen, argon/methane, helium or hydrogen. For packed columns, the
stationary phase is a liquid that has been coated on an inert granular solid (the column
packing) that is held in a length of borosilicate glass tubing. The column is installed in an
oven with the inlet attached to a heated injector block and the outlet attached to a detector.
Precise and constant temperature control of the injector block, oven and detector is
maintained. Stationary-phase material and concentration, column length and diameter,
oven temperature, carrier-gas flow and detector type (e.g. flame-ionization detection for
polycyclic aromatic hydrocarbons, electron-capture detection for phenolics,
organochlorinated insecticides and PCBs, thermionic specific detection for nitrogen-
Annex 2. Description of main water-quality monitoring methods and techniques
101
containing compounds or organophosphates, mass selective detection, etc.) are the
controlled variables.
When the sample solution is introduced into the column, the organic compounds are
vaporized and moved through the column by the carrier gas. They travel through the
column at different rates, depending on differences in partition coefficients between the
mobile and stationary phases.
Flame photometry: this makes possible the determination of trace amounts of lithium,
potassium, sodium and strontium, although other methods of analysis for lithium and
strontium are preferred.
The sample (after dilution, if necessary) is sprayed into a butane- or propane-air flame. The
alkali metals absorb energy from the flame and become raised to an excited energy state
in their atomic form. As these individual atoms “cool” they fall back into their original
unexcited or ground state and re-emit their absorbed energy by the radiation of specific
wavelengths, some of which are within the visible region of the electromagnetic spectrum.
This discrete emission is isolated by an optical filter and, for low concentrations, is
proportional to the number of atoms returning to the ground state. This, in turn, is
proportional to the number of atoms excited and, hence, to the concentration of the
element in the solution.
The minimum detection level for both potassium and sodium is approximately 100 μg l- 1.
The upper limit is approximately 10 mg l-1, but this may be extended by diluting the
samples.
11. Sampling procedures for isotopes in hydrological investigations
Detailed knowledge of hydrological systems forms an integral part of the sustainable
resource development. Isotope techniques are effective tools for satisfying critical
hydrological information needs like the origin of groundwater, recharge, residence time,
impact of climate change on water resources and interconnections of water bodies, among
others.
Applications of isotopes in hydrology are based on the general concept of “tracing”, in
which either intentionally introduced isotopes or naturally occurring (environmental)
isotopes are employed. Environmental isotopes (either radioactive or stable) have a
distinct advantage over injected (artificial) tracers in that they facilitate the study of various
hydrological processes on a much larger temporal and spatial scale through their natural
distribution in a hydrological system. Thus, environmental isotope methodologies are
unique in regional studies of water resources to obtain time- and space-integrated
characteristics, whereas the artificial tracers are generally effective for site-specific, local
applications.
In hydrological investigations, isotope techniques should be used routinely, together with
hydrochemical and hydrogeological techniques. As all isotopic, hydrogeological,
hydrochemical and hydrodynamic interpretations are space- and time-related, it is
imperative to consider all the related aspects of water-sampling and prevailing
hydrogeological conditions in a study area. More specific information on isotope
applications in hydrological and environmental studies is available from the Isotope
Hydrology Section of the International Atomic Energy Agency and WMO.
Appendix 1. Summary of water-quality guidelines and standards by
international organization or country
Source: GEMS/Water 2008, 111-112
Geographic
region
WHO
(guidelines)
European
Union
(standards)
Canada
(guidelines)
Australia
(guidelines)
Parameters
mg/l
mg/l
mg/l
mg/l
Algae, bluegreen
New
Zealand
(guidelines)
Japan
(standards)
United
States of
America
(standards)
mg/l
mg/l
mg/l
0.2
0.2
>1 toxic/
10 ml
Alkalinity
Aluminium
0.2
0.2
0.2
0.2
*
0.5
0.5
0.5
Antimony
0.005
0.005
0.006
0.003
0.003
Arsenic
0.01
0.01
0.01
0.007
0.01
Barium
0.3
#
0.7
0.7
2
*
#
0.004
0.004
0.3
0.001
0.001
4
1.4
1
Bromate
*
0.01
0.01
0.02
0.025
0.01
0
Cadmium
0.003
0.005
0.005
0.002
0.003
0.01
0.005
Ammonia unionized
Ammonia total
Beryllium
0.006
0.01
0
Bismuth
Boron
Calcium
*
300
Chloride
250
250
250
0.05
0.05
0.05
0/100 ml
0/100 ml
250
200
250
0.05
0.1
Chlorophyll a
Chromium
0.05
Cobalt
Coliform faecal
#
Coliform - total
#
0
0
>5 degrees
15 colour
units
Colour
#
#
&
Conductivity
^
^
^
Copper
2
2
2
1
2
1
1.3
Cyanide
0.07
0.05
0.05
0.08
0.08
0.01
0.2
Enterococci
0/250 ml
0/250 ml
Escherichia
coli
0/250 ml
0/250 ml
1.5
1.5
1.5
0.8
2
Hardness
*
#
Iron
#
0.2
0.2
Lead
0.01
0.01
0.01
Fluoride
>1/100 ml
1.5
1.5
Fluoride inorganic
DOC
Lithium
Magnesium
&
0.3
300
0.01
0.3
0.3
0.01
0.01
0
0.9
300
104
Planning of water-quality monitoring systems
Appendix 1 continued
Geographic
region
WHO
(guidelines)
European
Union
(standards)
Canada
(guidelines)
Australia
(guidelines)
New
Zealand
(guidelines)
Japan
(standards)
United
States of
America
(standards)
Parameters
mg/l
mg/l
mg/l
mg/l
mg/l
mg/l
mg/l
0.5
0.05
0.05
0.5
0.5
0.05
0.05
0.001
0.001
0.001
0.001
0.002
0.0005
Manganese
Mercury
Mercury inorganic
0.002
Methylmercury
Molybdenum
0.07
#
Nickel
0.02
0.02
0.02
50
50
Nitrate
Nitrate + Nitrite
0.05
0.07
0.02
0.02
50
50
10
10
Nitrite
0.5
0.5
Odour
&
&
3
1
&
Oil and grease
Orthophosphorus
Oxygen dissolved
Particulate
matter <2.5 µm
(PM<2.5)
pH
*
#
0.01
0.01
#
#
200
200
*
#
*
#
500
250
*
#
6.5–8.5
5.8–8.6
6.5–8.5
0.01
0.05
Phosphorus total
Potassium
Rubidium
Salinity
Selenium
Silver
Sodium
Solids – total
dissolved
(TDS)
Solids – total
suspended
(TSS)
0.01
200
0.01
0.01
0.1
0.02
180
0.1
200
&
500
500
250
Strontium - 90
Sulphate
250
Temperature
Thallium
Tin
1
0.0005
Total organic
carbon
Tritium
100 Bq/l
Turbidity
*
#
&
Uranium
*
#
0.02
Vanadium
1.4
#
3
#
Zinc
0.02
3
>2
degrees
n/a
1
5
0.002
Appendix 2. Key features of each chemical and physicochemical
quality element (QE) for lakes
Aspect/feature
Transparency
Thermal
conditions
Oxygenation
conditions
Salinity
Acidification
Measured
parameters
indicative of QE
Secchi depth,
turbidity, colour,
TSS
Temperature
DO,TOC, BOD,
COD DOC
Conductivity
Alkalinity, pH,
ANC
Relevance of QE
Eutrophication,
acidification
Hydrological
cycle, biological
activity
Production,
respiration,
mineralization
Agricultural,
domestic and
industrial
discharges
Thermal
discharges,
water
management in
reservoirs
Eutrophication,
organic pollution,
industrial
discharges
Industrial
discharges,
runoff
Acid rain,
industrial
discharges
High, influenced
by alloctonous
and
autochthonous
material
High,
influenced by
climate
conditions,
topography,
morphology
and waterbody
dimensions
Variable, diel
changes due to
respiration/
photosynthesis
Low-medium,
influenced by
climatic events
Low-medium,
influenced by
climatic events
Seasonal
variation
Seasonal
variation
(mixing and
stratification)
Diel variation,
high gradient in
stratified lakes
Seasonal
variation
Seasonal
variation
Sampling
methodology
In situ using
Secchi disc TSS,
field sample
collection
followed by
laboratory
analysis
turbidity, in situ
turbidimeters,
nephelometers;
colour: in situ
comparison to
Forel-Ule scale
or in laboratory
In situ using
thermistor
probes or
reversing
type Hg
thermometer
Online data
acquisition; in
situ submersible
probes; field
sample collection
followed by
laboratory Winkler
titration
In situ using
submersible
probes
In situ
measurement of
pH with probe;
sample collection
followed by
laboratory
analysis
Typical sampling
frequency
Monthly/
quarterly related
to the biological
elements
sampling
periodicity;
fortnightly or
monthly during
growth season
in Nordic
countries
Monthly/
quarterly
Depends on
morphological
characteristics of
lake: daily/monthly
or at the end
of stratification
periods (late
winter if ice cover
or late) summer
Monthly/
quarterly,
should be
measured
during
snowmelt or
heavy rainfall
events
Monthly/
quarterly, should
be measured
during snowmelt
or heavy rainfall
events
All seasons
All seasons
All seasons
All seasons
All seasons
Pressures
to which QE
responds
Level and sources
of variability of QE
Monitoring
considerations
Time of year of
sampling
Buffering
capacity,
sensitivity to
acidification
106
Planning of water-quality monitoring systems
Appendix 2 continued
Oxygenation
conditions
Salinity
Acidification
Water-column
profile
Single
measurements,
water column
profiles. 100 ml for
Winkler titration
In situ water
column profile,
integrated
epilimnion or
single sample
from outlet
(depending
on monitoring
purpose)
Single sample
from outlet of
lake or water
column profile
Simple, using in
situ probes
or surface water
sample
Simple, using
in situ probes
or water
samplers
Simple, using in
situ submersible
probes or sample
collection followed
by titration
Simple, using in
situ probe
Simple
Historical data
or data from
comparable
pristine lakes
Historical data
or data from
comparable
pristine lakes
Historical data
or data from
comparable
pristine lakes
Historical data
or data from
comparable
pristine lakes
Historical data
or data from
comparable
pristine lakes
No
No
No
No
No
Current use
in monitoring
programmes or
for classification
in EU
Yes
Finland, France,
Italy, Norway
Finland, France,
Italy, Norway,
Sweden
Belgium,
Finland, France,
Italy
Belgium, Finland,
France, Italy,
Norway, Sweden,
UK
Existing
monitoring
systems meet
requirements of
WFD?
No
No
No
No
No
Existing
classification
system meets
requirements of
WFD?
No
No
No
No
No
ISO/CEN
standards
No
No
ISO 5813:1983 DO
ISO 5815:1989
BOD5
Yes
Yes, no standard
for ANC
High
High
High
Moderate
High
Aspect/feature
Transparency
Typical “sample”
size
In situ
observations,
sample
collections
for chemical
analyses
(turbidity, TSS)
Ease of sampling/
measurements
Basis of any
comparison of
results/quality/
stations,
e.g. reference
conditions/best
quality
Methodology
consistent across
EU?
Applicability to
lakes
Thermal
conditions
Appendix 2. Key features of each chemical and physicochemical quality element (QE) for lakes
107
Appendix 2 continued
Aspect/feature
Main advantages
Main
disadvantages
Conclusions/
recommendations
Transparency
Thermal
conditions
Oxygenation
conditions
Salinity
Acidification
Simple to
measure,
provides longterm trends in
acidification.
Alkalinity is little
influenced by
anthropogenic
inputs (except
in acidified and
limed lakes). A
good correlation
was found with
MEI alkalinity and
phosphorus (P)
concentration,
allowing the
determination
of natural
background
(reference)
concentrations
for P.
Simple to
sample,
possibly the
most universally
used parameter
in limnology,
a simple and
powerful tool
for tracking
long-term
trends
Simple to
measure,
fundamental to
understand the
hydrological
cycle and lake
ecology
Simple to sample
and to measure,
extremely useful
because it can act
as an integrator of
lake health.
Simple to
measure,
conductivity
is little
influenced by
anthropogenic
inputs. A good
correlation
was found
with the MEI
conditions and
phosphorus (P)
concentration,
allowing the
determination
of natural
background
(reference)
concentrations
for P.
No
disadvantages
May require
intensive
monitoring for
appropriate
description
of thermal
conditions.
May require
intensive
monitoring
following
depletion events
in stratified lakes.
Does not
provide
long-term
information on
trends.
None
Easy to monitor:
the Secchi disc
is widely used
in limnology
for assessing
the biological
conditions
of lakes. In
humic lakes,
Secchi disc is
not useful for
assessment of
eutrophication.
Important
supporting
parameter for
interpreting
ecological
conditions;
seasonal
variation,
variation
with depth;
horizontal
variation should
be monitored in
large lakes.
Important
for lake
characterization,
e.g. gives an
indication of
lake mixing
processes
and metabolic
activity.
Important for lake
characterization;
acidity is
important
because it
governs the
chemical form
in which metals
occur in water
body. Alkalinity
and Its related
variables, pH
and conductivity
are important
classification
parameters.
Recommended
and particularly
important in deep/
stratified lakes
and lakes with ice
cover.
Appendix 3. Key features of each biological quality element (QE) for
lakes
Phytoplankton
Macrophytes
Phytobenthos
Benthic
invertebrates
Fish
Measured
parameters
indicative of QE
Composition,
abundance
biomass
(chlorophyll a),
blooms
Composition and
abundance
Composition
and abundance
Composition,
abundance,
diversity and
sensitive taxa
Composition,
abundance, sensitive
species and age
structure
Supportive/
interpretative
parameters
often/typically
measured or
sampled at the
same time
Nutrient
concentrations
(total/soluble),
chlorophyll,
DO, POC, TOC,
pH, alkalinity,
temperature,
transparency,
fluorometric in
situ monitoring
Nutrient
concentrations
(total/soluble)
in lake water,
sediment and
pore water,
substrate type,
pH, alkalinity,
conductivity,
transparency,
Secchi disc,
Ca concentration
Nutrient
concentrations
(total/soluble)
in lake water,
sediment and
pore water,
substrate type,
pH, alkalinity,
conductivity,
transparency,
Secchi disc, Ca
concentration
Nutrient
concentrations
(total/soluble),
DO, pH,
alkalinity,
sediment
analysis, toxicity
bioassays
Nutrient
concentrations
(total/soluble),
DO, pH, alkalinity,
temperature,
toxicity bioassays,
trophic condition,
zooplankton
dynamics, ANC, TOC
Eutrophication,
organic
pollution,
acidification,
toxic
contamination
Eutrophication,
acidification,
toxic
contamination,
siltation, river
regulation, lakewater level,
introduction of
exotic species
Eutrophication,
acidification,
toxic
contamination,
siltation, river
regulation, lakewater level,
introduction of
exotic species
Eutrophication,
organic
pollution,
acidification,
toxic
contamination,
siltation, river
regulation,
hydromorphological
alteration
(littoral)
Eutrophication,
acidification, toxic
contamination,
fisheries, hydromorphological
alteration,
introduction of exotic
species
Medium
Non-mobile
Non-mobile
Low to medium,
high when
hatching
High
Level and
sources of
variability of QE
High inter- and
intraseasonal
variation in
community
structure and
biomass;
medium-tohigh spatial
variability
Medium-high
seasonal
variability in
community
structure and
biomass, high
spatial variability
Medium-high
seasonal
variability in
community
structure and
biomass, low
interannual
variability,
high spatial
variability
Medium-high
seasonal
variability in
community
structure and
biomass,
high spatial
variability
High spatial and
seasonal variability,
populations clumped
with respect to
habitat variables
Presence in lakes
Abundant
Abundant, rare
in reservoirs
Abundant, rare
in reservoirs
Abundant
Abundant
Aspect/feature
Pressures
to which QE
responds
Mobility of QE
109
Appendix 3. Key features of each biological quality element (QE) for lakes
Appendix 3 continued
Aspect/feature
Phytoplankton
Macrophytes
Phytobenthos
Benthic
invertebrates
Fish
Qualitative
or semiquantitative
hand net or
kick-sampling;
Ekman grab or
core sampling.
Gear type
depends
on type of
substrate, e.g.
submerged
aquatic
vegetation – dip
net; sand and
clay – Peterson,
Van Veen grabs;
mud – Ponar,
Ekman grabs
Electrofishing net
captures, several
types (e.g. gillnets,
trammel net), trawls,
acoustic
Sampling
methodology
Integrated
or discrete
samples in the
water column,
1-5 sites per
lake. A number
of sampling
gear types are
commonly
used such
as hand-held
bottles or
flexible hose.
Aerial
photography
and/or transect
sampling
perpendicular to
the shoreline
In situ
observations
of occurrence
of natural
substrate in
littoral zone
and/or among
macrophyte
beds, as well
as scraping of
substrata
Habitats sampled
Water column
(i.e. epilimnion,
euphotic zone,
metalimnion)
Macrophytes:
littoral zone
Benthic
substrata/
artificial
substrata
Littoral,
sublittoral and
profundal
Littoral, open waters
Typical sampling
frequency
Monthly/
quarterly
In Nordic
countries,
6 times/
summer
Yearly (late
summer
in Nordic
countries), in
natural lakes
every 3-6 years
Varies from
several times
during the
growing season
to once a year
Yearly in natural
lakes every 3-6
years; twice a
year in littoral
waters
Depends on waterbody physical
characteristics and
objective, yearly
Late summer,
decided
by expert
judgement
Quarterly/
six-monthly/
several times
during the
growing
season;
in Nordic
countries,
no sampling
during ice cover
Early spring and
late summer
Late spring to early
autumn
Time of year of
sampling
All seasons,
at least twice
a year during
spring turnover
of temperaturestratified
water bodies
and summer
stratification;
in Nordic
countries,
no sampling
during ice
cover; more
stations are
required where
high spatial
variations are
expected.
110
Planning of water-quality monitoring systems
Appendix 3 continued
Aspect/feature
Typical sample
effort
Ease of sampling
Laboratory
or field
measurement
Phytoplankton
Macrophytes
Phytobenthos
Benthic
invertebrates
Fish
Depends on type
of sampling gear:
for electrofishing,
multiple habitats are
selected in littoral
areas based on
substrate and cover.
In shallow lakes,
fish can be sampled
with multimesh
gillnets and random
sampling; sampling
time 10-12 h
overnight, time less
in small lakes and
where fish densities
are high. In deeper
lakes, stratification
related to depth zones
is recommended.
Often 1 station
located in
centre of lake
3-10 transects
per lake with
2-3 quadrants
on each transect
should be
sufficient for the
majority of lakes.
Lake-wide,
3-10 transects,
littoral to
sublittoral
Lake-wide
composite
samples of
2/3 grabs at
each of 3-5 sublittoral sites (715 grabs total)
Relatively
simple
Variable,
requires
specialized
sampling
equipment
and relatively
specialized
personnel
with diving
qualifications.
Alternative
methods can be
used such as
drop cameras/
ROV/rakes.
Relatively
simple, some
difficulty in
deep lakes,
boat required
and expert
knowledge
of potential
hazards in
specific lakes
Relatively
simple, some
difficulty in
deep lakes,
boat required
and expert
knowledge
of potential
hazards in
specific lakes
Difficult, requires
specialized sampling
equipment.
Laboratory
sample
preparation
followed by
identification,
counting
and biomass
determination
under
microscopy;
algal toxin
determinations
in laboratory,
chlorophyll a
Field
measurements
through aerial
photography;
samples from
transects,
laboratory
identification to
species; analysis
of chlorophyll-a
content, fresh,
dry and AFDM,
organic content
Sample
processing in
the laboratory,
at least 100
organisms per
subsample (if
possible) are
identified to the
appropriated
taxonomic level
frequently to
species.
Sampling duration
and area or distance
sampled are recorded
in order to determine
the level of effort.
In the laboratory,
the specimens
are identified to
species, enumerated,
measured, weighted
and examined for the
incidence of external
abnormalities.
111
Appendix 3. Key features of each biological quality element (QE) for lakes
Appedix 3 continued
Aspect/feature
Phytoplankton
Ease and level of
Identification
Relatively
simple for
measures
based on high
taxonomic
levels (e.g.
family),
difficult for
identification
to lower
taxonomic
levels
(i.e. genus
and species),
biomass
evaluation
difficult
Macrophytes
Phytobenthos
Benthic
invertebrates
Fish
Identification
to species
relatively easy
with exception
of vegetative
stages of certain
genera
(e.g.
Potamogeton)
Identification
to species
relatively
easy for high
taxonomic
groups
(e.g. family),
difficult for
genus or
species and
biomass
evaluation
Relatively
simple for
measures
based on high
taxonomic
levels, difficult
for identification
to lower
taxonomic
levels
(i.e. species)
Relatively easy,
some difficulties may
appear with rare
specimens and
early fry.
Difficult to determine
because only
impacts of the
physicochemical and
hydromorphological
pressures are to
be addressed, not
fisheries/stocking/
species introductions.
Nature of
reference for
comparison of
quality/samples/
stations
Estimates of
phytoplankton
indicators/
indices (e.g. cell
density,
biovolume) to
be expected
in the absence
of significant
anthropogenic
pressures
Reference values
refer to typical
indicator values
(trophic ranking
score (TRS)) and
species diversity
of flora in lakes
not significantly
affected by
human activities
Little
knowledge
of reference
conditions for
phytobenthos
in lakes, no
established
methodology
Reference
values for
diversity,
abundance and
distribution
indices indicate
expected
conditions if
the lakes are
not significantly
affected
by human
activities.
References
set using the
25 percentile of
sites considered
unimpaired in
Sweden
Methodology
consistent across
EU?
No
No
No
No
No
Denmark,
Finland,
Ireland,
Netherlands,
Norway,
Sweden and
UK
Denmark,
Netherlands,
Norway,
Sweden, and UK
for conservation
No
Finland,
Netherlands,
Norway and
Sweden
Finland, Netherlands,
Norway and Sweden
Current use
in biological
monitoring or
classification in
EU
112
Planning of water-quality monitoring systems
Appendix 3 continued
Aspect/feature
Phytoplankton
Macrophytes
Phytobenthos
Benthic
invertebrates
Fish
Index of Biotic
Integrity incorporates
measurements of
fish assemblage
composition and
relative abundance;
percentage
of piscivore/
zooplanktivore
(surrogate for
age structure of
fish community);
percentage of
invertivore/omnivore
Current use of
biotic indicators
and indices/
scores
Taxonomic
analyses
(e.g. diversity
indices, taxa
richness,
indicators
species),
phytoplankton
total volume,
presence of
spring diatom
blooms,
occurrence of
harmful algae,
number and
proportion of
toxin-producing
cyanobacteria
(blue-greens)
TRS: species
with low TRS
values occur
primarily in
waters poor in
nutrients, while
high values
are associated
with eutrophic
waters), level of
diversity; relative
occurrence
of functional
groups,
Macrophyte
Trophic Index
(TIM).
No
Shannon’s
diversity index
(measure of
variation and
dominance
within animal
communities);
Average Score
Per Taxa index
related to the
occurrence of
sensitive (highindex value)
and tolerant
(low value)
species; Danish
fauna index
(evaluation of
the effects of
eutrophication
and organic
pollution in the
exposed littoral
zone of lakes);
Benthic Quality
Index (BQI)
to evaluate
eutrophication
and organic
pollution in the
deep bottom
areas); Organic
Carbon Ratio
(complementary
or alternative
to BQI); acidity
index (reflects
the presence
of species with
varying pH
tolerances.)
Existing
monitoring
system meets
requirements of
WFD?
No
No
No
No
No
Under
development
Under
development
Under
development
Under
development
Under development
High (very low in
reservoirs)
High (moderate
in reservoirs,
depending
on water
management)
Moderate
High (moderate to
low in reservoirs)
ISO/CEN
standards
Applicability to
lakes
High
113
Appendix 3. Key features of each biological quality element (QE) for lakes
Appendix 3 continued
Phytobenthos
Benthic
invertebrates
Fish
Easy to sample
and identify
(especially in
shallow water),
good indicator
of a broad range
of impacts,
especially
eutrophication
and siltation
Easy to identify
at family
level, good
indicator of
eutrophication
Easy to sample
(particularly in
shallow waters),
relatively simple
to analyse,
combines
chemical and
biological
features.
Possibility of adapting
classification systems
to incorporate the
requirements of WFD
Difficult to
sample in deep
waters, not
commonly used
in EU, lack of
information for
comparison
to reference;
methodology
needs to be
developed to
incorporate
requirements of
WFD.
No standard
methods, lack
of information
for comparison
with reference
conditions,
not commonly
used in EU;
methodology
needs to be
developed to
incorporate
requirements of
WFD.
Not commonly
used in EU, lack
of information
for comparison
with reference;
methodology
needs to be
developed to
incorporate the
requirements
of WFD, timeconsuming and
expensive to
analyse.
Requires specialized
sampling equipment;
methodology needs
to be developed
to incorporate the
requirements of WFD.
The
phytobenthos
holds an
important
role in the
metabolism of
lakes but there
is very little
experience and
information
on the use of
phytobenthos.
Further work is
required in this
area.
Important
parameter for
evaluating
other biological
components:
their use is at
an early stage
of development.
Meaningful
methodologies
must be
developed.
The drafting
of a suitable
guideline is part
of the method
development
of CEN. The
CEN group
recommends
that the
identification
of benthic
invertebrate
fauna should
be carried out
to the species
level.
Key biological
quality element,
can be difficult to
interpret (fishery,
biomanipulation,
etc.). integrates all
anthropogenic and
natural impacts.
The composition,
abundance and
structure of fish
communities can be
very useful indicators
of ecological quality.
Fish are only included
in monitoring
systems of a few EU
Member States.
Aspect/feature
Phytoplankton
Macrophytes
Main advantages
Easy to sample,
relevant for
water quality
and trophic
state, used in
many countries
to evaluate
eutrophication,
easy to
standardize
Main
disadvantages
Requires
taxonomic
expertise
for species
identification,
high temporal
variability
requires
frequent
sampling,
vertical and
horizontal
sample profiles
required due
to spatial
heterogeneity
Conclusions/
recommendations
Responds
rapidly to
changes in
phosphorus
concentration
levels,
identification
to order or
genus levels
is suitable/
recommended
for monitoring
phytoplankton
taxonomic
composition;
at present, it is
not clear that
identification
to species
represents a
substantial
improvement
of the
information
value of the
data, more
work required
in this area.
Key parameter
for evaluating
other biological
components
in lakes.
Macrophytes
hold an
important role in
the metabolism
of lakes but their
monitoring is
not frequently
used in the
assessment
of ecological
quality.
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Acronyms
AAS
atomic absorption spectrophotometry
AFDM
ash free dry mass
ANC acid neutralizing capacity
APHA
American Public Health Association
AVHRR
Advanced Very High Resolution Radiometer
BOD
biochemical oxygen demand
BQI
benthic quality index
CEN
European Committee for Standardization
COD
chemical oxygen demand
CSO
combined sewer overflow
DAP
data analysis protocol
DIN
Deutsches Institut für Normung (German Institute for Standardization)
DO
dissolved oxygen
DOC
dissolved organic carbon
DPSIR
Drivers-Pressures-State-Impact-Responses
EDI
equal-discharge increment
EEA
European Environmental Agency
EC
electrical conductivity
Eh
redox potential
ENVISAT
Environmental Satellite
EQC
external quality control
EU
European Union
Eurostat
Statistical Office of the European Commission
EWI
equal-width increment
GDE
groundwater-dependent ecosystems
GEMS
Global Environment Monitoring System (UNEP)
GEMStat
global water quality database (UNEP-GEMS)
GGMN
Global Groundwater Monitoring Network
GIS
Geographic Information Systems
GRDC
Global Runoff Data Centre
GWD
Groundwater Daughter Directive (EU)
IAEA
International Atomic Energy Agency
ICP-MS inductively coupled plasma-mass spectrometry
ICP-OES inductively coupled plasma-optical emission spectroscopy
IEC
International Electrotechnical Commission
IGRAC
International Groundwater Resources Assessment Centre
INSPIRE
Infrastructure for Spatial Information in the European Community (EU)
IQC
internal quality control
ISARM
International Shared Aquifer Resources Management
ISO
International Organization for Standardization
Acronyms
IT
information technology
JMP
Joint Monitoring Programme (WHO-UNEP)
LANDSAT
Land Satellite
LC
liquid chromatography
LEDs light-emitting diodes
MEI
Morphoedaphic Index
MERIS
Medium Resolution Imaging Spectrometer
MODIS
Moderate-resolution Imaging Spectroradiometer
MS
mass spectrometry
NASA
National Aeronautics and Space Administration (USA)
NGO
non-governmental organization
NOAA
National Oceanic and Atmospheric Administration (USA)
OECD
Organization for Economic Cooperation and Development
PCBs
polychlorinated biphenyls
PM
particuate matter
POC
particulate organic carbon
POPs
persistent organic pollutants
QA
quality assurance
QAO
quality assurance officer
QC
quality control
QE
quality element
QM
quality management
QMS
quality-management system
redox
reduction-oxidation
ROV
remotely operated vehicle
SOP
standard operating procedure
TC
total carbon
TDS
total dissolved solids
TERRA
NASA Earth Observation Satellite
TIM Macrophyte Trophic Index
TOC
total organic carbon
TRS
trophic ranking score
TSS
total suspended solids
UNECE
United Nations Economic Commission for Europe
UNEP
United Nations Environment Programme
UNICEF
United Nations Children’s Fund
US EPA
United States Environmental Protection Agency
UV
ultraviolet
VKI
Von Karman Institute for Fluid Dynamics
WQ
water quality
WQM
water-quality monitoring
WISE
Water Information System for Europe
WFD
Water Framework Directive (EU)
117
For more information, please contact:
World Meteorological Organization
Communications and Public Affairs Office
Tel.: +41 (0) 22 730 83 14/15 – Fax: +41 (0) 22 730 80 27
E-mail: [email protected]
Hydrology and Water Resources Branch
Climate and Water Department
E-mail: [email protected]
7 bis, avenue de la Paix – P.O. Box 2300 – CH 1211 Geneva 2 – Switzerland
www.wmo.int
P-CLW_13108
Tel.: +41 (0) 22 730 84 79 – Fax: +41 (0) 22 730 80 43
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