Dietary uptake from historically contaminated sediments as a source of PCBs to migratory fish and invertebrates in an urban estuary.

Migratory fish and invertebrate samples were analyzed for polychlorinated biphenyls (PCBs) to study bioaccumulation in an urbanized estuary in the northeastern USA. Fish were also analyzed for (13)C, (15)N, and (34)S ratios. Results from several approaches (stable isotopes, total PCB concentrations, congener ratios, and bioaccumulation factors, BAFs) suggested that the fish and invertebrates fell into two distinct dietary groups: the more planktonic butterfish and squid versus a benthic group composed of lobsters, scups, and crabs. Both benthic and pelagic fish obtained the majority of their PCB body burdens from the sediments. Lobsters seemed to have an additional uptake from sediment particles, as observed by an increase in highly chlorinated congeners' bioaccumulation. BAFs were calculated relative to passive sampling-derived dissolved concentrations of PCBs. BAFs exceeded K(ow) values, implying that PCBs were accumulated beyond equilibrium partitioning with the water column. This was supported by comparison of chemical activity gradients, which suggested chemical activities of hexa- and heptachlorobiphenyls in biota exceeded those in water and porewater, but not for tetra- and pentachlorobiphenyls in squids and butterfish.