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U.S. Geological Survey Open-File Report 2005-1001
USGS East-Coast Sediment Analysis: Procedures, Database, and GIS Data
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Pipette Method

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Image shows equipment used in pipette method.
The most commonly performed sedimentation-based procedure for the analysis of the fine fraction of sediments is the pipette method. This method, which is based on Stoke’s Law, requires that the analyst has removed the coarse fraction from the sample, that the fine fraction is about 15 grams, that the suspension remains at a constant temperature and contains a known amount of dispersant (usually 0.5% sodium hexametaphosphate), and that the volume of the suspension is exactly 1000 ml.
Image shows the analyst stirring the suspension.
To start the procedure, vigorously stir the suspension. Begin at the bottom with short rapid strokes, working up the cylinder with progressively longer strokes until all of the sediment is evenly distributed. When stirring is complete, start the timer.
Image shows sample being withdrawl.
After 20 seconds, insert the pipette to a depth of 20 cm and withdraw exactly 20 ml.
Image shows the withdrawn sample being emptied into a pre-weighed beaker.
Empty the pipette into a pre-weighed beaker,
Image shows the pipette being rinsed.
and rinse the pipette with a small amount of distilled water. Continue withdrawals at the specified depth and time intervals. If more than one sample is to be analyzed at a time, care must be taken to ensure that no withdrawal times, or the procedures to be performed at those times, overlap.
Image shows samples placed in oven for drying.
The solid content of each withdrawal is determined by evaporation or oven drying
Image shows sample being weighed.
and weighing, with corrections for the dissolved dispersant and salts.
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Coastal and Marine Geology Program
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