DIFFERENTIAL BIOACCUMULATION OF NON-ORTHO-SUBSTITUTED AND OTHER PCB CONGENERS IN COASTAL ARCTIC INVERTEBRATES AND FISH

The composition of 47 ortho- and seven non-ortho-substituted PCBs in s ediment, water, invertebrates, and fish collected from Cambridge Bay, Northwest Territories, Canada, is presented. The congener composition in sea urchins (Strongylocentrotus droebachiensis) was attributed to d ifferences in the log K-ow of individual congeners during uptake from ingested sediment and aqueous solubility during secondary uptake from the water column. Four-horn and short-horn sculpins exhibited selectiv e bioaccumulation of the recalcitrant congeners: those lacking two non -chlorinated carbons in adjacent meta and para positions on the biphen yl ring. The presence of methyl sulfone PCBs in four-horn sculpin live r provided direct evidence for metabolism. The percent composition of total PCB levels in four-horn sculpin livers, contributed by non-ortho -substituted PCBs 77 and 126 (those with potential for dioxin-like tox icity), was relatively constant regardless of total PCB concentration, suggesting that for a given species increased exposure to PCBs does n ot lead to increased relative concentrations of non-ortho-substituted congeners. Limited data on congeners 77 and 126 in sediment, sea urchi ns, or four-horn sculpins suggests that, with increasing trophic statu s, these congeners were diminished rather than enriched relative to th e total PCB concentration.