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CORVALLIS, Ore. - High in mountain lakes and far north in Alaskan wilderness, researchers from Oregon State University are finding some of the world's most toxic chemicals, possibly from sources as far away as Europe and Asia.

"We've found persistent chemicals - such as mercury and PCBs - in lakes in very remote areas," said Michael Kent, director of the center for salmon disease research at OSU. "And we've found evidence of toxic effects in fish in these lakes."

Kent heads the fish pathology investigation of the Western Airborne Contaminant Assessment Program (WACAP), a collaboration of government and university scientists conducting a six-year study in national parks from California to Alaska.

Far from the crowds of national park visitors, OSU researchers trek to wilderness lakes in the high Sierras, Rockies, and Cascade Mountains, as well as Alaska back country. They carry the bare essentials: 2,000 pounds of scientific equipment, inflatable boats, hand pumps, dry ice, food and shelter for eight people for three days. In the winter, they sample the snowpack and return with sleds and backpacks full of frozen samples. They are measuring mercury and other contaminants in snow, soil, air, water, fish and vegetation in places once thought to be among the most pristine areas in the world.

"Places that are far removed from human activity, places high in altitude or high in latitude, were thought to be pristine," said Carl Schreck, a professor in OSU's Department of Fisheries and Wildlife who heads the fish physiology investigations. "They are not. Nothing is pristine anymore, and that makes it hard to determine a baseline for measuring environmental change."

The researchers' sampling methods target different time periods. They sample this year's snowpack to get a snapshot of current airborne pollutants; they examine lake sediments for evidence from as far back as the 1870s.

"We have seen physiological and pathological changes in the fish in these lakes and we have seen an accumulation of toxic chemicals in the water that could only have come in by air," Kent said.

Although the specific sources of these airborne contaminants are as yet unknown, other studies have shown that air masses can cross the Pacific Ocean from Asia to North America in just a few days.

These air masses can carry coal smoke (a major source of mercury) and polychlorinated biphenyls (PCBs) emitted from industrial sites in Russia, China and elsewhere. When the air masses hit the mountains of western North America, the pollutants they carry begin to settle.

Staci Simonich, a professor in OSU's Department of Environmental and Molecular Toxicology, is an expert in tracking signatures of airborne pollutants in global air currents. She leads the project's assessment of persistent organic pollutants.

"These compounds can travel long distances in the atmosphere, and they concentrate in cold environments." Simonich explained. "Their chemistry allows them to volatilize and rise, then settle out for a time before volatilizing and rising again. As they warm and cool they hop-scotch their way into higher elevations."

Many of these organic compounds settle in fatty tissues of fish, wildlife - and humans - and can reduce immune functions and reproductive success, and increase risk of cancer. Preliminary results indicate the presence of persistent organic pollutants, including compounds banned in the U.S. such as dieldrin, in water, snow and lichen at several of the study sites.

The Western Airborne Contaminant Assessment Program has study sites in eight parks at high elevation or high latitude, including Sequoia, Rocky Mountain, Glacier, Olympic, Mount Rainier, Denali, Noatak, and Gates of the Arctic national parks.

These are remote places. In one of the study sites in Alaska, no one had visited the place since the team was there two years earlier.

"A float plane drops us off with all our equipment, and we hope the weather holds so the plane can come back to get us in three or four days," said Adam Schwindt, an OSU researcher with the WACAP team. "We're catching and dissecting fish all day, in a place surrounded by brown bears."

After thorough laboratory and data analyses, the researchers will report their findings on the contaminant impacts to high elevation and high latitude ecosystems to the National Park Service in 2007.

"National parks as remote, ecologically sensitive sites may become the bellwether to understand the environmental impact of these toxic compounds in North America," said Dixon Landers, WACAP's lead scientist from the U.S. Environmental Protection Agency Western Ecology Division.

For more information on the project, go online at: http://www2.nature.nps.gov/air/studies/air_toxics/wacap.cfm