Turbidity - Columbia Riverkeeper

Turbidity - Columbia Riverkeeper
Turbidity
Equipment List
1 Turbidity Kit containing;
Turbidity meter-always use on level, stationary surface
Box containing 3 gel standards and 3 empty cells
Silicone Oil
Lint Cloth
Logbook
Large nalgene sample bottle with lid (not included in kit)
Considerations
Human recreation disturbs sediment and increases turbidity. Turbidity is usually greater
in shallow water. If duplicate samples vary greatly, take a 3rd sample to identify the
range. Significant rainfall greatly effects turbidity.
Accuracy Check – check logbook to see if it has been completed already
1. Clean gel standards with cloth to wipe away lint and finger prints. Use silicone oil if
needed.
2. Holding from the lid to avoid fingerprints on glass, place the first Standard (0-10
range) in the cell compartment of the meter with the white diamond on the vial
aligning with the orientation mark on the meter. Close the lid.
3. Press power. Be sure the automatic range is set and the display shows “AUTO
RNG.” If not, set by pressing the “RANGE” key until displayed. Press “READ.”
The display will show “----- NTU”.
4. Record the NTU value in the logbook. If the reading is not within 5% of the Standard
([ |reading-standard| / standard ] x 100), clean the standard and try again. If it is still
off, contact Columbia Riverkeeper.
5. Repeat this procedure with the remaining two Standards (0-100 and 01-1000 ranges).
Sample Measurement
1. At the river fill a nalgene bottle by submerging your arm to your elbow. If you are
doing duplicates, hold two bottles side by side and submerge together. If you are
measuring more than 10 minutes after collecting the sample, be sure to gently invert
the sample container to re-suspend the sediment. Do not shake as this will introduce
NTU-altering air bubbles. Fill one of the glass sample cells to the top.
2. Wipe the bottle first with the rag provided to dry. Then with a soft, lint-free cloth to
remove water spots and fingerprints. Beware of fogging cells in cooler weather.
3. Holding from the lid, place the sample cell in the cell compartment of the meter with
the white diamond on the vial aligning with the orientation mark on the meter. Close
the lid.
4. Press power. Be sure the automatic range is set and the display shows “AUTO
RNG.” If not, set with the “RANGE” key until displayed. Press “READ.” The
display will show “----- NTU”. Record the value and clean the sample cell.
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