University of Washington scientists say they may have determined why mercury in the atmosphere might be washed out more easily than earlier believed.
Scientists for years have been unable to explain high levels of the chemical in fish found far from industrial sources of mercury pollution.
The latest research suggests mercury can be carried long distances in the atmosphere, combining with other airborne chemicals that are much more water-soluble and, therefore, more easily washed from the air in rainfall.
Philip Swartzenruber, a UW doctoral student, notes mercury generally is present in the atmosphere in only very small amounts compared with other pollutants. However, mercury doesn't break down, so after washing from the atmosphere it can be converted to a more toxic form -- methyl mercury.
Swartzenruber says the more toxic form of mercury can become very concentrated.
"By the time mercury gets to the top of the food chain, it can increase by a factor of a million," he said. "It can go from being nearly undetectable in the air to being toxic to larger organisms."
Swartzendruber presented his team's findings last week during the American Geophysical Union's fall meeting in San Francisco.
Copyright 2005 by United Press International
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