Hotspots Of Mercury Contamination Found In Eastern North America

A U.S. and Canadian research team surveying mercury contamination in fish and birds in the northeastern United States and southeastern Canada has identified five "hotspots" where concentrations of the element exceed those established for human or wildlife health, according to a Jan. 3 announcement.

The researchers said that their findings have implications for federal "cap-and-trade" approaches being implemented for regulation of emissions from coal-fired electric power plants.

The team focused on levels of the potent neurotoxin in yellow perch and common loons, but the research also took into account contamination in other fish, birds and mammals. In addition to these hotspots in New England, New York and Nova Scotia, the researchers found nine "areas of concern" in these regions and in Quebec and New Brunswick. Findings from the team's analysis are summarized in the January issue of BioScience, a publication of the American Institute of Biological Sciences (http://www.aibs.org/core/index.html).

The hotspots are believed to result from complex processes that move atmospherically released mercury through the environment, and from site-specific characteristics such as the high sensitivity of wetlands and forested areas to mercury inputs. Local sources of mercury are also significant. Fish consumption advisories responding to mercury contamination exist in all the states and provinces included in the study, and loons are adversely affected by mercury levels they experience.

On March 15, 2005, EPA issued a federal rule to address mercury emissions from coal-fired power plants. The Clean Air Mercury Rule establishes "standards of performance" limiting mercury emissions from new and existing coal-fired power plants and creates a market-based cap-and-trade program.

According to the agency, the Clean Air Mercury Rule will build on EPA's Clean Air Interstate Rule (CAIR) to significantly reduce emissions from coal-fired power plants -- the largest remaining sources of mercury emissions in the country. When fully implemented, these rules will reduce utility emissions of mercury from 48 tons a year to 15 tons, a reduction of nearly 70 percent, the agency stated.

According to the researchers, cap-and-trade approaches seek to reduce the total release of mercury but could lead to static or increased emissions in some areas. Greater deposition of mercury near areas that are highly sensitive to the element or that are already affected by it could raise the risk to people and wildlife that consume fish. The researchers said that there is reason to believe, however, that lowering emissions can reduce risk: an analysis of levels of mercury contamination over time in the Merrimack River watershed suggests that lowered emissions reduced mercury levels in biota within a few years.

The 10-member research team was led by David C. Evers of the BioDiversity Research Institute in Gorham, Maine (http://www.briloon.org). The study was based on samples collected over four years by the Northeastern Ecosystem Research Cooperative and made use of 7311 observations for seven species. The study report in BioScience is accompanied by an overview article, written by Charles T. Driscoll of Syracuse University and colleagues, that summarizes current knowledge about mercury contamination in the region; the authors conclude that reductions in mercury emissions beyond those currently under way will be needed to eliminate the element as a health risk to humans or to populations of loons.

For more information on health effects from mercury, go to http://www.epa.gov/mercury/effects.htm.

This article originally appeared in the 01/01/2007 issue of Environmental Protection.

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