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 tiss ues of marine biota (macrophytes, snails, urchins, bivalves, sea cucum bers, fishes) taken from Midway Atoll, PCBs 138, 153, 170, 180 and 187 were the most abundant congeners in all samples analysed, Distributio n of PCB congeners was shifted in favour of higher (hexa- and chlorina ted congeners in all species; only macrophytes displayed significant b ioaccumulation of lower (tri- and tetra-) chlorinated congeners, Evide nce is presented for the differential metabolism of congeners by marin e species. Non-ortho substituted congeners (PCBs 77, 126) with elevate d toxic potency were not present at significant levels in the sampled species, Certain mono-ortho congeners (PCBs 105, 118), implicated in m arine mammal toxicity, comprised only approximate to 4.5% of total con gener load in prey for piscivorous birds and marine mammals. (C) 1997 Elsevier Science Ltd.