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Collection Methods

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Once collected, bed sediment is processed for three sample types. One sample is sieved to less than 63 um and analyzed for trace elements, major ions, and organic and inorganic carbon. A second sample is sieved to less than 2.0 mm and and analyzed for organic contaminants, total-organic carbon, total-inorganic carbon, and percent moisture. The third sample is sieved to less than 2.0 mm and analyzed for percent particle-size distribution less than 63 um.

The composite sample is first thoroughly mixed in a glass bowl using a Teflon spatula.

Trace Elements
A 63-um nylon-sieve cloth is stretched over a plastic-sieve frame, and the retaining ring is attached. This is then placed over a glass plate. A small amount of composite sample is placed onto the sieve with a spatula. Using native water, the sample is pressure sieved and collected by the plate. The material on the plate is then scaped into a 500 mL plastic receiving bottle. This procedure is repeated until approximately a depth of 1 cm is obtained. The sample is then stored in a refrigerator until the sediment has settled and the water is clear. This can take 2 or 3 days, but no longer than a week. The liquid is decanted to approximately 1 cm of the sediment/water interface with a syringe. The sample is then sent to a laboratory for further processing.

Organic Contaminants
A 2.0-mm stainless-steel sieve is placed over a 1,000 mL glass jar. An aliquot (2 to 3 tablespoons) of the sample is worked through the sieve, without water, with a Teflon spatula. The jar is filled approximately half full since 500 mL of wet sediment is needed for analysis.

Particle Size
A 2.0-mm stainless steel sieve is placed over a 1,000-mL plastic jar. The sample is sieved until 2 cm of wed sediment accumulates into the jar. For particle-size analysis, 50 g of dry weight of material is needed.