Tuesday, 26 July 2011

Toxins locked in Arctic deep freeze released by melting ice

Vancouver Sun:
Environment Canada sleuths have found that toxins such as PCBs that have been locked in an Arctic deep freeze are being "remobilized" as the climate warms.

In a report published Sunday, they say that persistent organic pollutants, known as POPs, which were banned decades ago, are being released in the Arctic as sea ice retreats and temperatures rise.

"Our results indicate that a wide range of POPs have been remobilized into the Arctic atmosphere over the past two decades as a result of climate change, confirming that Arctic warming could undermine global efforts to reduce environmental and human exposure to these toxic chemicals," Hayley Hung, an Environment Canada research scientist, and her colleagues reported in the journal Nature Climate Change.

Large amounts of the toxic chemicals were transported to the North from factories and farmers' fields on air currents and ended up trapped in Arctic ice, and frigid northern soils and sea water.

Until recently scientists and regulators thought the Arctic toxins would stay out of circulation permanently, but Hung says that view changed with some "very abnormal' readings in recent years.

Scientists have measured the old pesticide hexachlorocyclohexane, which was banned years ago, coming out of open water in Hudson Bay and the Beaufort Sea.

And polychlorinated biphenyls, or PCBs, widely used as coolants and lubricants until they were banned in many countries more than two decades ago, have been picked up at the edge of the ice in the Atlantic Arctic.

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