Olympic National Park to warn anglers of mercury levels in fish
By Brian Gawley, Peninsula Daily News
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Mercury concentrations in some fish in the Olympic National Park lakes were among the highest measured in a six-year study of 20 national parks and monuments released by the National Park Service last week.
The amount exceeded the 185 parts per billion standard that triggers warnings for people.
The scientific director of the multi-agency study said there's no danger to those who enjoy the park.
"I think everybody must make up their own mind, but generally speaking there's no threat to being in the park," said Dixon Landers of Corvallis, Ore., a senior research environmental scientist for the Environmental Protection Agency.
"People should always listen to state health advisories."
Park officials are developing language to include in its fishing fliers and Web site to let people know about the assessment results, said park spokeswoman Barb Maynes.
"It wasn't that all fish were found to be higher, but that some fish in the two lakes exceeded the maximum acceptable mercury levels."
The levels of mercury were "enough that it is important to let people know," she said.
Mercury concentrations also were well into the danger zone for wildlife that eat fish, including kingfisher birds, otters and mink.
The two lakes were the only ones in the park that were studied.
Pollution in pristine areas
The study was funded primarily by the National Park Service to evaluate the potential threats to park ecosystems and likely sources of these contaminants.
The study found evidence of 70 contaminants, including heavy metals and pesticides, of parks ranging from Denali in Alaska to Big Bend in Texas.
The study by the Western Airborne Contaminants Assessment Project was released Tuesday.
The findings show that even the most pristine wilderness areas are within reach of toxic byproducts of industry.
Because the locations are rarely visited by people, the prime source of the pollution is from the air.
Contamination from pesticides and flame retardants is believed to have more local sources, whereas the origins of mercury pollution are regional and global.
PJ and Hoh lakes are deep in wilderness areas.
PJ Lake is at 4,700 feet in the Hurricane Ridge area of the park, and hosts brook trout.
Hoh Lake is found at 4,540 feet in the Hoh area of the park, and also hosts brook trout.
"The findings that were most surprising or notable were the relatively high level of mercury found in the fish in the two lakes," Maynes said.
"It's only two lakes, so it's not a large sample, but it is notable."
Maynes said the risk to people is considered low.
The risk varies according to location, frequency and type of fish consumption, she said, adding that most people are not likely to eat enough of the contaminated fish to be hurt by it.
Mercury airborne?
All the lakes studied had mercury levels that exceeded health standards for humans or the animals studied, Landers said.
There's some evidence that mercury is drifting across the Pacific Ocean to the West Coast from coal-fired plants in Asia — but it's hard to discern global versus regional sources, Landers said.
Air pollution could be a contributor to the study's findings, he said, but added that it's not quite that simple.
The mercury cycle is complex.
The source of elevated mercury levels in fish studied could be deposits from human sources or natural sources, he said.
"Historically, it's been atmospheric deposition according to lake sediments, but that doesn't necessarily mean the mercury is available to fish," Landers said.
There needs to be not just a source but also an environment for that mercury to become what scientists call, "metylized" or oxidized, he said.
Then the mercury can enter the food web and biomagnify or begin increasing in concentration, Landers said.
"The highest concentration was in Arctic lakes, but the tundra there is wetlands in summer, and its watershed process [is] responsible," he said.
In the case of the two Olympic lakes with high mercury levels, there must be some watershed processes to create these relatively elevated levels, Landers said.
"We didn't look at the wetlands and watershed or food web processes, but that's probably where the difference lies," he said.
"We haven't addressed the air pollution yet."
Mercury has a one to two year life span in the atmosphere.
About two-thirds of mercury in the environment comes from human sources, especially coal-fired processes, Landers said.
"So we are having an impact on mercury in the atmosphere and we can see that in the sediments," he said.
The high mercury concentrations probably also are due to studying long-living fish that eat other fish, providing more time and opportunities for the mercury to become concentrated, he said.
Fish caught at Mount Rainier's Golden Lake also were contaminated with mercury and had the highest amounts of flame retardants called polybrominated diphenyl ethers, or PBDEs.
The PBDEs probably came from Seattle and other urban areas, Landers said.
"These are not toxic waste dumps in national parks, but they are downstream of places that are industrialized," said Daniel Jaffe, a scientist at the University of Washington —Bothell.
Guidelines for safe consumption of recreationally caught fish are available at the state Department of Health Web site at www.doh.wa.gov/ehp/oehas/fish/.
Last modified: March 01. 2008 9:00PM