Persistent organochlorine pollutants in ringed seals and polar bears collected from northern Alaska

Blubber samples from ringed seal ŽPhoca hispida; n 8. and polar bear subcutaneous fat ŽUrsus maritimus; n 5. were collected near Barrow, Alaska in 1996 as part of the Alaska Marine Mammal Tissue Archival Project ŽAMMTAP. and retained in the National Biomonitoring Specimen Bank at the National Institute of Standards and Technology in Gaithersburg, Maryland ŽUSA.. The samples were analyzed for a variety of persistent organochlorine pollutants ŽPOPs. including polychlorinated biphenyls ŽPCBs., hexachlorocyclohexanes ŽHCHs., chlordane and metabolites, hexachlorobenzene ŽHCB. and DDTs and metabolites. The geometric mean, on a wet mass basis, of PCBs Žsum of 29 congeners and congener groups. were 732 282 ng g Ž1 S.D.. in seals and 3395 1442 ng g in polar bears. The geometric mean of DDTs, HCHs Ž -, - and - HCH. and HCB concentrations Žwet mass basis. in seals and bears were 562 261 ng g vs. 74.8 39 ng g, 380 213 ng g vs. 515 ng g, and 17.4 10.1 ng g vs. 183 153 ng g, respectively. The geometric mean sum of chlordane Ž chlordane, sum of cis- and trans-chlordane, cis- and trans-nonachlor, oxychlordane and heptachlor epoxide. and dieldrin concentrations in ringed seals and polar bears were 753 617 ng g vs. 720 315 ng g and 38.6 22.8 ng g vs. 130 65 ng g, respectively. Apparent bioaccumulation factors Žpolar bear ringed seal POP concentrations. were lower in the animals sampled near Barrow, Alaska than in those from locations in the Canadian Arctic. This suggests that polar bears are also preying on marine mammals from lower trophic levels than the ringed seals with correspondingly lower organochlorine levels, such as bowhead whale carcasses. PCB congener patterns in the samples demonstrated the metabolism of certain PCB congeners in the polar bear relative to the ringed seal in agreement with previous studies. Regional comparisons of animals collected in Alaska and Arctic Canada are presented.