Marine mammals as global pollution indicators for organochlorines

Blubber tissues of the following marine mammals differing in their geographic distribution (North Atlantic, North Pacific, Bering Sea/Arctic Ocean), trophic level, and feeding habits were analyzed for their organochlorine contents: two seal species (harbor seals--Phoca vitulina, northern fur seals--Callorhinus ursinus), three toothed whale species (belukha whales--Delphinapterus leucas, one common dolphin--Delphinus delphis, one pilot whale--Globicephala melaena), and one baleen whale species (a bowhead whale--Balaena mysticetus). As xenobiotics were quantified the seven indicator congeners of the polychlorinated biphenyls (PCB 28, 52, 101, 118, 138, 153, and 180), three isomers of the hexachlorocyclohexanes (alpha-, beta- and gamma-HCH) as well as six components of the DDT-group (4,4'-DDT, 4,4'-DDD, 4,4'-DDE, 2,4'-DDT, 2,4'-DDD, and 2,4'-DDE). When comparing the xenobiotic levels of these marine mammals, it showed that the animals from the western North Atlantic were contaminated about 15 times more with organochlorines than the animals from the eastern North Pacific and the Bering Sea/Arctic Ocean. The total organochlorine burden, the 4,4'-DDE-percentage as well as the metabolic PCB patterns correlate with the trophic levels of the marine mammals studied. The quantitative analyses were done by high-resolution capillary gas chromatography with electron capture detection (HRGC/ECD) whereas the analyses of the metabolic PCB patterns were done by high-resolution capillary gas chromatography and mass selective detection (HRGC/MSD).