OCCURRENCE AND DISTRIBUTION OF MERCURY IN MAMMOTH CAVE NATIONAL PARK

The fate and transport of mercury in Mammoth Cave National Park (MCNP) will be examined in order to determine mercury’s mobility in surface and ground water. Mercury (Hg) is a persistent neurotoxin that is easily transported through karst aquifer systems; for example, the South Central Kentucky Karst (SCKK) ecosystem, which includes the MCNP area. The largest source of mercury to MCNP is atmospheric deposition, largely produced by coal-fired power plants. Hg from the atmosphere deposits in rivers, sediments, and organisms through rain, wind, and bioaccumulation. Significant increases in atmospheric mercury can be expected because more than 20 power plant applications are being considered in Kentucky.

The current data shows a potential threat of Hg levels in the drinking water and Hg bioaccumulation in a number of surface and subsurface organisms of MCNP. Background levels of mercury, 0-25 ppt in the water and 0-3000 ppb in the sediment have been observed. Hg concentrations in aquatic organisms at the park are 0-0.50 ppm. Mercury transport in ground water and surface water at in Mammoth Cave National will be determined. Results will be complemented by an investigation of the extent of bioaccumulation of mercury in fish and mussels. The correlation of the levels and distribution of mercury in fish and mussels with levels of mercury measured in the atmosphere, water and sediments will be examined. The physical and geochemical processes that govern the fate and transport of mercury in a karstic aquifer system will be determined through a series of batch and column studies.