MUIR, Derek C.G.; Environment Canada, NWRI, Burlington ON: Spatial and Temporal Trends of Contaminants in Arctic Marine Environments

Although Arctic marine biota were first demonstrated in the 1970s to have accumulated elevated levels of persistent organic pollutants (POPs) and mercury (Hg), there was limited knowledge until recently of the sources, pathways, levels, spatial and temporal trends and biological effects of these substances in Arctic species. Over the past 50 years the Arctic Ocean and marine food web have become a sink for POPs emitted from industrial and agricultural activities mainly located in temperate regions of the northern hemisphere. In the case of Hg the story is more complex with global emissions as well as local geology both playing a role. Levels of POPs such as PCBs, DDT residues (sDDT) and polybrominated diphenyl ether (PBDE) flame retardants in polar bear, ringed seals and seabirds, are highest in the European Arctic and lowest in the western North American Arctic. Highest concentrations of PCBs in polar bear were found in samples from the Kara Sea and Franz Josef Land and continued use of PCBs in Russia may be the source. PCBs and sDDT concentrations have decreased significantly in seabird eggs and in ringed seal blubber in the Canadian arctic since the 1970�s. DDT had the largest decline of any POPs measured in seal blubber; 2-3 fold in the Canadian Arctic over 25-30 years. PBDEs are doubling every 4-5 years in ringed seals. Perfluorinated acid surfactants have achieved high levels, compared to chlorinated or brominated POPs, in polar bears, although their temporal trends are not known. Hg levels in liver of beluga from the Mackenzie Bay have increased 3-fold during the 1990s but show little increase in eastern Canadian arctic animals. These spatial and temporal trends need to be interpreted in the context of possible dietary shifts, climate warming and changing regional sources of POPs and Hg.