New Scientist 17 Apr 09;
FOR Arctic peoples, global warming is not just transforming their land, it is also poisoning their food. Mercury levels in seals and beluga whales eaten by Inuit in northern Canada have reached levels that would be considered unsafe in fish.
Now, Gary Stern of Canada's Department of Fisheries and Oceans in Winnipeg, Manitoba, and colleagues have found that seal meat contains more mercury in low-ice years, suggesting the problem will only get worse.
The team sampled ringed seals caught by traditional hunters in the western Canadian Arctic between 1973 and 2007. Mercury levels were higher after summers with less sea ice. They think this is because Arctic cod flourishes in low-ice years. Because Arctic cod is higher up the food chain than the seals' other food, their tissues accumulate more mercury (Environmental Science and Technology, DOI: 10.1021/es803293z).
Arctic residents may well be exposed to other pollutants, too. Melting ice releases chemicals such as DDT and PCBs that leached from the atmosphere decades ago and became entombed in ice and permafrost, warns Philippe Grandjean of Harvard University. As the ice melts, its contaminants flow into streams, rivers and the Arctic Ocean.
It may already be too late to prevent a surge of pollutants from polar ice, says Grandjean. However, he notes, policy-makers can try to prevent the same thing happening again by reducing pollutants still in use, such as flame retardants.
