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 sediment, water, invertebrates, and fish collected from Cambridge Bay, Northwest Territories, Canada, is presented. The congener composition in sea urchins (Strongylocentrotus droebachiensis) was attributed to differences 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 selective bioaccumulation of the recalcitrant congeners: those lacking two non-chlorinated carbons in adjacent meta and para positions on the biphenyl ring. The presence of methyl sulfone PCBs in four-horn sculpin liver 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 toxicity), was relatively constant regardless of total PCB concentration, suggesting that for a given species increased exposure to PCBs does not lead to increased relative concentrations of non-ortho-substituted congeners. Limited data on congeners 77 and 126 in sediment, sea urchins, or four-horn sculpins suggests that, with increasing trophic status, these congeners were diminished rather than enriched relative to the total PCB concentration.