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 parts per trillion (ppt) in the water and 0-3000 parts per billion (ppb) in the sediment have been observed. 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 parts per million (ppm)). Mercury levels in different bat species, including federally listed endangered species in the park have been determined and found to be 1-9 ppm. Quality analysis and quality control tests were done using human hair reference standards. Mercury concentrations in bats collected at various locations during summer 2004 and summer 2005 and hair from archival bats were analyzed and compared in order to investigate the potential for mercury bioaccumulation.