Collecting sediment samples for analysis of contaminants—particularly in river systems—is not just a matter of going out with a bucket and shovel. In fact, it is much more complex than a water quality survey, aquatic biota survey, or any terrestrial sampling program. Monitoring of sediment contaminants frequently is done to determine whether the sediments are a sink or a source of the chemicals of interest, and to evaluate the effects of the contaminants on the aquatic ecosystem as a whole.