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USGS Contributes to the Design of a Proposed National Mercury Monitoring Network (MercNet)

Map of states with mercury fish consumption advisories (EPA, 2008)
States with mercury fish consumption advisories (EPA, 2008). Every state has at least one advisory.

Scientists from many federal and state agencies, tribes, and private institutions gathered at the National Mercury Monitoring Workshop in May 2008 to craft "a strategy for designing and implementing a collaborative, integrated national network for monitoring the ecological responses of mercury deposition." The result of their efforts is a report, entitled "MercNet—Establishing a Comprehensive National Mercury Monitoring Network". The report summarizes the findings of the workshop and presents the strategy for a nationally-distributed, mercury monitoring network. U.S. Geological Survey (USGS) scientists provided technical input for the design of the proposed comprehensive and integrated network for tracking mercury pollution in ecosystems nationwide.

The impetus for the workshop was the widespread occurrence (see map) of mercury-contaminated game fish and the potentially harmful exposure to people and wildlife that eat the fish. Every state has at least one mercury fish consumption advisory, and presently 23 states have issued “statewide mercury advisories”. In most instances, the source of mercury is atmospheric deposition of mercury that is released to the atmosphere by industrial sources, such as coal combustion and waste incineration, and by natural sources, such as volcanoes and volatilization (evaporation) from the ocean surface. Given the right environmental conditions, atmospherically deposited mercury is converted into highly toxic and bioavailable methylmercury, which efficiently biomagnifies in food webs and can reach levels of toxic concern in fish, wildlife, and humans. Currently there is not adequate information to assess the benefits and effectiveness of mercury emission reduction measures on ecological health. To address this information gap the workshop participants proposed MercNet—a comprehensive and integrated mercury-monitoring network for the United Sates. As envisioned, MercNet will provide policymakers, regulators, scientists, water-resource managers, environmental professionals, and the public with the information needed to adequately and accurately quantify (1) regional and national changes in atmospheric mercury deposition, (2) mercury contamination of ecosystems, and (3) bioaccumulation of mercury in fish and wildlife in response to changing mercury emissions.


National Mercury Monitoring Workshop Steering Committee, 2009, MercNet-Establishing a Comprehensive National Mercury Monitoring Network: Publisher--Heinz Center, Distributor--National Atmospheric Deposition Program, p. 37 (2008 National Mercury Monitoring Workshop Report, Annapolis, Md., May 5-7, 2008)

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