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. 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. Observed levels of mercury in fish and clam samples are comparable to values observed in other studies (0-0.50 ppm). Mercury levels in different bat species in the park have been examined which show 2-6 ppm. There is little data that can be used to predict to what degree atmospheric deposition of mercury will impact the SCKK ecosystem; therefore, sampling in MCNP and the study of Hg's mobility characteristics will continue through 2008.