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. The South Central Kentucky Karst (SCKK) ecosystem, which includes the MCNP area, is a local aquifer system. 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. There are over 20 power plant applications under consideration in the Commonwealth of Kentucky; therefore, significant increases in atmospheric deposition of mercury at the Park can be expected. A total of 14 locations in the park are sampled, 13 of these are sampled every month for mercury in water and seasonally for mercury in sediments. 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. As expected, mercury levels in water are quite low (0-25 ppt) since mercury preferentially binds to sediments and organic material. Mercury levels in the sediments range between 0-3000 ppb. A number of surface and subsurface organisms are endangered or declining in MCNP due to bioaccumulation of mercury. 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 2006.
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