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Mercury Found to Migrate Horizontally from Landfill

USGS scientists collecting gas samples from the unsaturated zone
USGS scientists collecting gas samples from the unsaturated zone. Subsurface gases are drawn through a small glass tube filled with an adsorbing material, which traps mercury or volatile organic compounds for later analysis.

U.S. Geological Survey (USGS) scientists working at the Amargosa Desert Research Site (ADRS) in arid southwestern Nevada found that mercury gas can migrate horizontally over long distances through the unsaturated zone. These findings published in Applied Geochemistry highlight the potential for mercury exposure well beyond the edge of a landfill. Mercury contained in buried landfill waste was known to migrate vertically and be released via upward emission to the atmosphere or downward leaching to groundwater. The scientists found elevated levels of mercury gas in the deep unsaturated zone at distances of 100 to 160 meters from the closest waste burial trench. The study also demonstrates that the prevailing scientific understanding of how gases migrate in the unsaturated zone is inadequate for explaining the pattern of mercury movement through the layers of sediment in the subsurface at the ADRS. Future research will focus on improving understanding of mercury fate and transport from arid waste sites in order to minimize human and ecological exposure. Environmental professionals can use these new findings in their assessments of the potential for mercury exposure and to develop sound waste-disposal practices concerning mercury.

Mercury in Landfills

Common sources of mercury in landfills include electrical switches, fluorescent light bulbs, batteries, thermometers, and some medical waste. Exposure to mercury may cause brain, liver, kidney and developmental disorders, particularly in young children and developing fetuses. Mercury is often a constituent in gases that are emitted from landfills.

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Walvoord, M.A., Andraski, B.J., Krabbenhoft, D.P., and Striegl, R.G., 2008, Transport of elemental mercury in the unsaturated zone from a waste disposal site in an arid region: Applied Geochemistry, v. 23, no. 3, p. 572-583, doi:10.1016/j.apgeochem.2007.12.014.

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