Chlorinated Hydrocarbon Contaminants in Polar Bears from Eastern Russia, North America, Greenland, and Svalbard: Biomonitoring of Arctic Pollution
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Adipose tissue samples from polar bears (Ursus maritimus) were obtained by necropsy or biopsy between the spring of 1989 to the spring of 1993 from Wrangel Island in Russia, most of the range of the bear in North America, eastern Greenland, and Svalbard. Samples were divided into 16 regions corresponding as much as possible to known stocks or management zones. Concentrations of dieldrin (DIEL), 4,4′-DDE (DDE), sum of 16 polychlorinated biphenyl congeners (ΣPCB), and sum of 11 chlordane-related compounds and metabolites (ΣCHL) were determined. In order to minimize the effect of age, only data for adults (320 bears age 5 years and older) was used to compare concentrations among regions. Concentrations of ΣPCB were 46% higher in adult males than females, and there was no significant trend with age. Concentrations of ΣCHL were 30% lower in adult males than females. Concentrations of ΣPCB, ΣCHL, and DDE in individual adult female bears were standardized to adult males using factors derived from the least-square means of each sex category, and geometric means of the standardized concentrations on a lipid weight basis were compared among regions. Median geometric mean standardized concentrations (lipid weight basis) and ranges among regions were as follows: ΣPCB, 5,942 (2,763–24,316) μg/kg; ΣCHL, 1,952 (727–4,632) μg/kg; DDE, 219 (52–560) μg/kg; DIEL, 157 (31–335) μg/kg. Geometric mean ΣPCB concentrations in bears from Svalbard, East Greenland, and the Arctic Ocean near Prince Patrick Island in Canada were similar (20,256–24,316 μg/kg) and significantly higher than most other areas. Atmospheric, oceanic, and ice transport, as well as ecological factors may contribute to these high concentrations of ΣPCB. ΣCHL was more uniformly distributed among regions than the other CHCs. Highest ΣCHL concentrations were found in southeastern Hudson Bay, which also had the highest DDE and DIEL concentrations. In general, concentrations of ΣCHL, DDE, and DIEL were higher in eastern than western regions, suggesting an influence of North American sources. Average ΣPCB concentrations in bears from the Canadian Arctic were similar to those in 1982–84, while average ΣCHL and DDE concentrations were 35–44% lower and DIEL was 90% lower. However, the significance of these temporal trends during the 1980s is not conclusive because of the problems of comparability of data.
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