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), that are correlated with Hg in surface waters. We hypothesized that watershed characteristics control Hg concentrations in northeastern lakes. Specifically, we suggested that low-conductivity, wetland-dominated systems with high DOC concentrations will have higher Hg concentrations than high-conductivity higher trophic-level lakes. We linked landscape statistics calculated using spatial analysis (GIS) to a regional lake data set that contains total Hg (THg, range=0.1-6.42 ng/L), methyl Hg (MeHg, range=<0.02-0.76 ng/L), and full ion chemistry. The lake data set was the EPA Eastern Lake Survey II statistical population of lakes in the Northeastern U.S. plus 11 Vermont LTM lakes, all sampled within a single summer index period during 2004. These same lakes were sampled during 1984 and 1986 by US EPA (though not for Hg). We developed and compared four statistical models predicting THg and MeHg from these sets of variables.
Funding: Northeastern States Research Cooperative, 2007-2008, Evaluating spatial patterns in mercury and methyl mercury in northeastern lakes: landscape setting, chemical climate, and human influences (S. Nelson, J.S. Kahl, D. Krabbenhoft, N. Kamman)
I also participated in a project that assessed major ion chemistry and pH, plus zooplankton community structure and composition (with funding from US EPA), in the same set of lakes, during the same sampling campaign.
Funding: U.S. Department of Agriculture/Northeastern States Research Cooperative, 2003, Evaluating scope and trends for the base cation decline in surface waters of the northeastern US (J.S. Kahl, J. Stoddard, R. Church, S. Nelson, L. Rustad, K. Webster, I. Fernandez, R. Stemberger)
Report: Rosfjord, C.H., J.S. Kahl, K. Webster, S. Nelson, I. Fernandez, L. Rustad, R. Stemberger, 2006. Final Report: Acidic deposition-relevant changes in lake chemistry in the EPA Eastern Lake Survey, 1984-2004. Submitted to USDA NSRC.