Elevated mercury levels found in lake
Great Salt Lake measures highest among U.S. lakes
State officials who are conducting a study of selenium levels in the Great Salt Lake would like more funding to check for mercury in brine shrimp and waterfowl.
Diane Nielson, the Department of Environmental Quality's executive director, said mercury in the lake's south arm is at the highest level measured by the U.S. Geological Survey in any body of water tested in the United States. The levels were confirmed by sampling carried out by Kennecott. The highest levels were in the deep brine layer, she said Wednesday at a meeting of the Legislature's Natural Resources, Agriculture and Environment Interim Committee.
The nature and extent of the mercury in the lake should be examined, with cost estimated at $1.5 million, according to information Nielson supplied.
Mercury in large bodies of water is not necessarily harmful. It is dangerous when changed by biological activity and concentrated in organisms, becoming a toxic contaminant. It tends to concentrate as it moves up the food chain, so large fish are more likely to have high levels.
Jeff Salt, Great Salt Lakekeeper in the Lakekeeper organization, said in a sheet given to the Deseret Morning News that biological samples showed adult brine shrimp and eared grebes were very high in toxic methylmercury. He added that adult brine shrimp were tested, not the eggs that are harvested.
"Adult brine shrimp feed on algae and bacteria that uptake and concentrate methylmercury from the salt water, and then the eared grebes feed on the brine shrimp," says the sheet.
A question raised by Sen. Tom Hatch, R-Panguitch, during the interim meeting concerned whether mercury in the lake could affect prawns. In some aquaculture farms, these edible shrimp are fed brine shrimp from the Great Salt Lake.
The brine shrimp harvest gathers the tiny animals' eggs. The eggs can remain viable for months when dried. Brine shrimp hatch from the eggs when the eggs are put into water.
Nielson told the Deseret Morning News Thursday that a USGS fact sheet discusses mercury content in brine shrimp and eared grebes. Total mercury levels and total methylmercury levels appear elevated but further study is warranted, she said.
"What we are doing right now on the lake as part of the Great Salt Lake Selenium Study, is looking at selenium concentrations related to brine shrimp," she said. Selenium is a substance known to harm waterfowl in high enough concentrations. The study involves brine shrimp larvae.
Nielson believes the state should examine mercury levels in brine shrimp too. The question is whether to do it now, during the selenium study, or take it up as a separate investigation, she said.
"We might be able to do sampling and analysis for mercury at the same time we're doing selenium for about $340,000," Nielson said in a telephone interview. To do it separately, after the selenium study is finished, could cost about $1.5 million for additional sampling and other costs.
The source of the lake's mercury will remain a mystery at least until further study. But about a third of the mercury in the environment comes from natural sources such as deposits in rocks, while the rest is emitted by human actions, according to the DEQ.
Much of the human-caused contamination comes from worldwide emissions from power plants, hazardous waste incineration, cement factories and other industrial activities, according to state figures.
Utah's mercury emissions are relatively small, ranking seventh among 10 Western states in terms of emissions from power plants. Power plant releases in this state are higher only than those in Oregon and California, while New Mexico and Wyoming emit the most.
The reason for the difference involves the size of power plants and the type of coal used, say experts. Burning coal releases mercury, which is mixed with coal.
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