Exploring the Spatial Association between Environmental Methylmercury and Atmospheric Deposition at Varying Geographic Scales

Steven Porter* and Gary Conley**
Ohio University
Center for Air Quality
Building 22, The Ridges
Athens, Ohio 45701

Over the past few decades, researchers have explored the relationship between concentrations of the neurotoxin methylmercury and sources of mercury emissions to the atmosphere with little success. More recently, researchers have begun to examine the spatial relationship between environmental methylmercury and ecosystem factors known to enhance the formation of methylmercury. Using comprehensive fish tissue data from the State of Ohio Cooperative Fish Tissue Monitoring Program and atmospheric deposition data from the National Atmospheric Deposition Programís National Trends Network, this study attempts to explore the strength of spatial associations between these datasets at varying scales. Statistical methodologies were employed using analytical tools in ArcGIS, including radius of influence and distance weighted averaging. Associations were identified that address uncertainties when comparing local, regional, and global factors of environmental methylmercury formation. The results of this study imply that methylmercury investigations may be scale dependent.

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