Distribution patterns of polychlorinated biphenyl congeners in water, sediment and biota from Midway Atoll (North Pacific Ocean)

To increase our understanding of critical pathways of polychlorinated biphenyl (PCB) transfer from abiotic media into marine organisms, this study quantified 20 PCB congeners in surface water, sediment and tissues of marine biota (macrophytes, snails, urchins, bivalves, sea cucumbers, fishes) taken from Midway Atoll. PCBs 138, 153, 170, 180 and 187 were the most abundant congeners in all samples analysed. Distribution of PCB congeners was shifted in favour of higher (hexa- and above) chlorinated congeners in all species; only aquatic macrophytes displayed significant bioaccumulation of lower (tri- and tetra-) chlorinated congeners. Evidence is presented for the differential metabolism of congeners by marine species. Non-ortho substituted congeners (PCBs 77, 126) with elevated toxic potency were not present at significant levels in the sampled species. Certain mono-ortho congeners (PCBs 105, 118), implicated in marine mammal toxicity, comprised only ≈4.5% of total congener load in prey for piscivorous birds and marine mammals.