AP Environmental Writer
DETROIT — Mercury levels have dropped about 20 percent in the Great Lakes in recent decades but remain dangerously high and are getting worse in some places, scientists said in a report released Tuesday.
Concentrations of mercury exceed the risk threshold for people and wildlife at many spots across the region and are particularly high in inland waterways, said the report issued by the Great Lakes Commission, an agency that represents the eight states and two Canadian provinces surrounding the lakes. The report said scientists had found mercury is toxic to fish and wildlife at surprisingly low levels.
The report was issued the day after 25 states asked a federal court to block limits on mercury and other air pollution from power plants that the Environmental Protection Agency plans to set next month. Michigan Attorney General Bill Schuette, who led the effort, said the regulations would hurt the economy and cause electric rates to jump. The Republican-controlled U.S. House last week voted to delay rules to cut emissions from cement plants, solid waste incinerators and industrial boilers.
Authors of the Great Lakes report said lower emissions from incinerators were largely responsible for the mercury drop-off.
“Logic would suggest if we controlled them further, we would be even more successful,” said Charles Driscoll, a Syracuse University environmental engineer.
The report was based on what Tim Eder, the Great Lakes Commission’s executive director, said was the most thorough evaluation of mercury pollution trends ever conducted in the region. It involved 170 researchers who produced 35 peer-reviewed papers after taking more than 300,000 measurements, including samples from birds, fish and sediment.
The overall decline in mercury contamination is “very welcome news,” said study co-author James Wiener of the University of Wisconsin at La Crosse.
But reasons for concern remain, he said. Six commonly eaten game fish had average mercury concentrations above the EPA’s designated safe level in more than 60 percent of the area studied. An uptick in concentrations of some fish and wildlife such as loons in Wisconsin, eagles in Minnesota and walleye in Ontario lakes is worrisome — largely because scientists don’t know why it’s happening, Wiener said.
“The more we look, the more samples that are taken, the more evidence of mercury we find,” Eder said.
A study led by David Evers, executive director of the Biodiversity Research Institute in Maine, found the Adirondack mountain range in New York is a hot spot because heavy forest cover and plentiful wetlands promote the chemical reaction that causes mercury to concentrate as it moves up the food chain. The situation is similar elsewhere in the northern Great Lakes region, such as Michigan’s Upper Peninsula.
Mercury is a powerful toxin that can damage the human nervous system, particularly in young children. Fetuses exposed to mercury can develop brain damage, blindness and seizures.
Humans with high levels of mercury usually get them by eating contaminated fish. Most states issue advisories warning people to limit consumption of fish species with high levels of mercury and other contaminants.
Mercury pollution in the Great Lakes began rising in the mid-1800s from sources such as burning coal, incinerating waste, mining and metal smelting. Levels peaked in the 1980s before dropping as pollution controls kicked in. Despite a 60 percent decline in emissions from human activities between 1990 and 2005, about 100 tons are generated from human activities each year, the report said.
Even as the U.S. has cracked down on emissions, they’ve risen elsewhere, particularly in fast-growing nations such as China and India. But the research found the drop in mercury levels in soils around the Great Lakes region came as emissions from sources in the region fell by nearly half.
“U.S. sources are the dominant influence on mercury in the Great Lakes region,” said Kathy Fallon Lambert of Harvard University, who also contributed to the report. Coal-fired power plants are “the single largest remaining uncontrolled source in the U.S.,” she said.
Schuette and the other states that filed a brief with the U.S. District Court in Washington, D.C., want the effective date of EPA’s power plant rules to be delayed one year.
“We are very glad to hear mercury levels are down in the Great Lakes and in this situation simply ask for time to properly study the complex regulatory proposals to ensure we protect the environment and jobs,” spokesman John Sellek said.