Evaluating spatial patterns in mercury and methyl mercury in northeastern lakes: landscape setting, chemical climate, and human influences

Principal Investigators:

• Sarah J. Nelson, Senator George J. Mitchell Center at the University of Maine
• Steve Kahl, Center for the Environment, Plymouth State University
• D.P. Krabbenhoft, U.S. Geological Survey
• N.C. Kamman, Vermont Department of Environmental Conservation

Abstract:

Mercury (Hg) contamination of surface waters and biota is widespread in the Northeast. Although watershed processing of Hg is complex, several research projects have identified landscape factors such as wetland extent and forest type, and chemical co-variates such as dissolved organic carbon (DOC), as controls on Hg in surface waters. We hypothesize that watershed characteristics control Hg concentrations in the Northeast. Specifically, we suggest that low-conductivity, wetland-dominated systems with high lake DOC concentrations will have higher Hg concentrations than high-conductivity higher trophic-level lakes affected by human development. This project will linklandscape statistics calculated using spatial analysis to a coordinated data set that contains total Hg (HgT), methyl Hg (MeHg), and full ion chemistry for a statistical population of lakes in the Northeastern U.S.,all sampled within a single summerindex period. Results will be compared to previous survey and data compilation projects for the region, and because the study lakes are the same sampled as part of U.S. EPA’s Eastern Lakes Survey in 1984, we will compare patterns to twenty years of trend data for major ions and DOC. The final coordinated database and metadata will be available to other researchers and agency staff working on Hg modeling in the region and nationally. The overarching goal is to identify landscape types conducive to high surface water Hg levels, thus results will be summarized and interpreted for resource managers via World Wide Web outlets and presentations.