Toxicity of marine sediments supplemented with mixtures of selected chlorinated and aromatic hydrocarbons to the infaunal amphipod Rhepoxynius abronius

The toxicity of a reference sediment supplemented with mixtures of seven aromatic hydrocarbons (fluoranthene, phenanthrene, benz[a]anthracene, benzo[a]pyrene (BaP), 2,6-dimethylnaphthalene (DMN), 1-methylnaphthalene, and 2-methylnaphthalene, or four chlorinated hydrocarbons (polychlorinated biphenyls (PCBs, Aroclor 1254), hexachlorobutadiene, 2,2-bis( p-chlorophenyl)-1,1,1-trichloroethane and hexachlorobenzene) was evaluated in amphipod ( Rhepoxynius abronius) lethality bioassays. Significant mortality occurred among amphipods exposed for 10 days to a reference sediment (46% fines, 0·9% total organic carbon) supplemented with a mixture of chlorinated hydrocarbons at concentrations (0·05–1·0 μg g −1 dry wt) approximating those measured in contaminated sediments of Puget Sound, WA, as well as at concentrations five times as great (5 ×). In contrast, sediments supplemented with the aromatic hydrocarbon mixture were toxic only at the higher (5 ×) concentrations (0·5–15·0 μg g −1 dry wt). Sediment concentrations of the mixture components and their bioavailability to amphipods were assessed using radiolabeled PCBs, DMN and BaP. Measurement of radioactivity incorporated by R. abronius after the 10-day exposure period indicated a dose-related uptake of xenobiotic compounds from both the chlorinated and aromatic hydrocarbon-supplemented sediments. Dimethylnaphthalene and the metabolically refractive PCBs were bioaccumulated to a greater extent than BaP, which is known to be metabolized extensively by R. abronius.