ABSTRACT
Bottom sediments serve as reservoirs for many persistent chemicals in aquatic systems, and consequently, sediments in polluted areas often contain high concentrations of these chemicals. Test organisms most often recommended in sediment bioassays, including bioaccumulation tests, are benthic or epibenthic invertebrates. In bioaccumulation tests, fish may not provide the same results as invertebrates. In the US, current regulations for evaluating the suitability of dredged material from freshwater for disposal are basically the US Environmental Protection Agency (EPA) 1977 bulk sediment criteria. In addition to laboratory assays, field assessment of bioaccumulation is another viable evaluation technique. The length of bioassays for sediment bioaccumulation has been controversial because the short tests (10 day) and the longer tests (28 day) have benefits and drawbacks. One of the generally accepted parts of a sediment bioaccumulation test is purging, a period following the exposure during which the test animals are removed from contaminated sediment and placed in clean tanks, with or without uncontaminated sediment.
