A RECORD OF MERCURY ACCUMULATION IN BAT GUANO DEPOSITS

The potential for environmental impacts or damage from atmospheric deposition of mercury from existing and proposed coal-fired power plants and the subsequent contributions to mercury loading in surface and ground-water is a national problem. Research into the toxic effects of mercury bioaccumulation is vital. Methylation is the most biologically relevant step in mercury speciation that influences the fate and transport of mercury in the environment. Bats are particularly vulnerable to Hg and MeHg bioaccumulation because they are small, mobile, long-lived, and generally consume 40-100% of their body mass in prey each night. In addition, bats are also exposed to contaminants through the placenta, nursing, breathing, and drinking water. Given the high toxicity of Hg and MeHg and the relative paucity of toxicological data on Hg and MeHg with respect to bats, research and monitoring has found that the range of total mercury in adult bat hair is 1 to over 10 mg/kg from over 350 samples from MCNP demonstrates the vital need to further develop this research. A subset of samples had mercury analysis completed from both hair and guano from individuals with guano levels ranging from 0 to almost 1 mg/kg. Moreover, coring, dating and sampling of deep guano deposits have the potential for examining mercury levels in bat populations prior to extensive development of coal fired power plants. The core may also contain a stratographic record of the foraging and atmospheric environment. A 40-cm long core of bat guano with a 3-cm diameter was collected in fall 2010 from Trail 10 Bat Cave in the Withlacoochee State Forest in Citrus County, Florida. The guano core was divided into 28 sections. For each section, 1-2 samples were collected. Total mercury was analyzed for each sample 2-4 times. Five samples were set aside for future C-14 dating to try to correlate the extent of the mercury concentrations with the anthropogenic time frame. This work was conducted as part of a National Science Foundation REU project at Western Kentucky University.