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Mercury characterization in Lahotan Valley Wetlands

In 1999, the Nevada Fish and Wildlife Office of the U.S. Fish and Wildlife Service and the Superfund Division, U.S. Environmental Protection Agency, Region 9 initiated a joint investigation to evaluate extent and severity of mercury contamination in ecologically important wetlands in Lahontan Valley, Churchill County, Nevada.

Total mercury (HgT) and methylmercury (MeHg) concentrations were determined in water and sediment in principal wetlands on Stillwater and Fallon National Wildlife Refuges (NWR). Previous investigations found that HgT is widely distributed in sediment in Lahontan Valley. We found the greatest HgT concentrations in sediment from wetlands that historically received inflow from Carson River channels that existed prior to dam construction. HgT concentrations progressively declined in sequential wetlands in this flow-through wetland system. Most of the HgT in corixids existed as MeHg. The statistically significant relationship between MeHg in corixids and MeHg in sediment suggests that sediment plays a key role in the biological availability of mercury in Stillwater NWR wetlands. HgT and MeHg concentrations in water, sediment, and corixids present a risk to fish and wildlife on Stillwater NWR, Fallon NWR, and other wetlands in Lahontan Valley. In 1999, MeHg concentrations in about half of the corixid samples exceeded concentrations associated with long-term reductions in avian productivity. However, concentrations were well below levels associated with major toxic effects.

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United States of America
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agINFRA The RING is part of the agINFRA project EC 7th framework program INFRA-2011-1.2.2 - Grant agr. no: 283770