Is global warming concentrating Mercury in Arctic food-chain?

A Euronews report on contamination of the arctic food chain with high concentrations of methylmercury, a highly toxic form that builds up in fish and the animals that eat them.

European researchers are taking a close look at polar precipitation, trying to understand more about concentrations of mercury at the North Pole. It’s part of a wide range of research projects undertaken for the “International Polar Year.” Scientists are looking into how and why the highly toxic heavy metal is finding its way into the food chain.

www.damocles-eu.org

Ice crystals, mercury implicated in Arctic pollution

University of Michigan report:

Frost flowers. Diamond dust. Hoarfrost.

These poetically named ice crystal forms are part of the stark beauty of the Arctic. But they also play a role in its pollution, according to a new study by scientists at U-M, the Cold Regions Research & Engineering Laboratory and the University of Alaska.

After collecting and analyzing hundreds of samples from the Alaskan Arctic, the researchers determined ice crystals that form from vapor clouds billowing up from cracks in sea ice help concentrate mercury from the atmosphere, and certain types of crystals are more efficient than others. Their results appear in the cover article for the March 1 issue of Environmental Science & Technology.

“Previous measurements had shown that in polar springtime, the normally steady levels of mercury in the atmosphere drop to near zero, and scientists studying this atmospheric phenomenon had analyzed a few snow samples and found very high levels of mercury,” says Joel Blum, the John D. MacArthur Professor of Geological Sciences. “We wanted to understand what’s controlling this mercury deposition, where it’s occurring and whether mercury concentrations are related to the type and formation of snow and ice crystals.”

Mercury is a naturally occurring element, but some 150 tons of it enter the environment each year from human-generated sources, such as incinerators, chlorine-producing plants and coal-fired power plants, in the United States. Precipitation is a major pathway through which mercury and other pollutants travel from the atmosphere to land and water, says lead author Thomas Douglas of the Cold Regions Research & Engineering Laboratory in Fort Wainwright, Alaska.

Once mercury from the atmosphere is deposited onto land or into water, micro-organisms convert some of it to methylmercury, a highly toxic form that builds up in fish and the animals that eat them. In wildlife, exposure to methylmercury can interfere with reproduction, growth, development and behavior and may even cause death. Effects on humans include damage to the central nervous system, heart and immune system. The developing brains of young and unborn children are especially vulnerable.

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