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. Although mercury is not directly harmful at ambient levels, it is concentrated up to a millionfold and chemically modified in aquatic food chains, resulting in dangerous levels of methylmercury in some wildlife species. 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.
The hotspots have implications for "cap and trade" approaches being implemented for regulation of emissions from coal-fired electric power stations, which, along with municipal waste incinerators, are major sources of mercury pollution. 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. There is reason to believe, however, that lo
Source:American Institute of Biological Sciences