文摘
Legacy organochlorine contaminants were determined in adipose tissues from 294 polar bears (Ursus maritimus) sampled in East Greenland in 23 of the 28 years between 1983 and 2010. Of 19 major legacy contaminants and congeners (¦²PCB, 4 PCB congeners (CB153, 180, 170/190), ¦²DDT, p,p¡ä-DDE, p,p¡ä -DDD and p,p¡ä-DDT, ¦Á- and ¦Â-hexachlorocyclohexane (HCH), HCB, octachlorostyrene, dieldrin, oxychlordane, cis- and trans-chlordane, cis- and trans-nonachlor, heptachlor epoxide and BB-153), 18 showed statistically significant average yearly declines of ? 4.4 % (range: ? 2.0 to ? 10.8 % /year) among subadult polar bears (i.e. females < 5 years, males < 6 years). For example, the ¡Æ PCB concentrations declined 2.7 fold from 22 730 ng/g lw (95 % C.I.: 12 470-32 990 ng/g lw) in 1983-1986 to 8473 ng/g lw (95 % C.I.: 6369-9776 ng/g lw) in 2006-2010. Similar but fewer statistically significant trends were found for adult females and adult males likely due to smaller sample size and years. Despite declines as a result of international regulations, relatively high levels of these historic pollutants persist in East Greenland polar bear tissues.
