Geographical differences and time trends of persistent organic pollutants in the Arctic.

Geographical and temporal trends of total PCBs (SigmaPCBs) and hexachlorocyclohexanes (SigmaHCHs) have been examined in polar bear (Ursus maritimus) adipose tissue and ringed seal (Phoca hispida) blubber along a transect from Alaska to Svalbard and northern Norway/western Russia. PCB concentrations in polar bear show a strong west to east trend with higher levels in east Greenland, Svalbard. In ringed seal, highest PCB levels were found at two sites near the Russian coast. SigmaHCHs levels in ringed seals and polar bear show the reverse trend coinciding with much higher levels of SigmaHCHs in seawater in the North American Arctic. Some of these geographical differences may reflect dietary differences especially in the case of PCBs. Levels of SigmaPCBs in polar bears in the eastern Canadian Arctic appear to have increased from the 1970s to the 1980s but are now on the decline. SigmaPCBs and SigmaHCHs levels showed no significant change from the mid-1980s to 1990s in ringed seal blubber from three locations in the eastern Canadian Arctic.