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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