Assessment of Hg in Sediments, Waters, and Biota of VT and NH Lakes

Project Objectives and Location:

Throughout New England, there exists compelling data indicating that mercury in the environment is resulting in hazards to human health and wildlife. Notably, advisories to limit the consumption of a variety of fish species from freshwater lakes have been issued across northern New England in recent years. In response to this, the Vermont Department of Environmental Conservation (VTDEC) and the New Hampshire Department of Environmental Services (NHDES), in collaboration with Dr. Charles Driscoll from Syracuse University, are undertaking a three-year study of mercury in sediments, waters, and biota of Vermont and New Hampshire lakes. This cooperative project is sponsored by the United States Environmental Protection Agency (USEPA) - Region 1, the USEPA Office of Research and Development in Athens, GA, VTDEC, and NHDES. Collaborators to the project also include the Biodiversity Research Institute of Freeport, Maine, Dr. Dan Engstrom of the Science Museum of Minnesota, the US Fish and Wildlife Service (Region 1), and the Vermont Department of Fish and Wildlife. The goal of this project is to determine which larger, publically used Vermont and New Hampshire lakes are of the type that 1) have excessive mercury in their sediments, 2) possess the conditions linked to processing mercury into its toxic form, and 3) have high mercury concentrations in plankton, fish, and fish-eating wildlife. The results of this study will be used in part to refine fish tissue consumption advisories in Vermont and New Hampshire, and in part to learn more about the process of bioaccumulation of mercury in freshwater biota. The results of this study will also serve baseline chemical and biological indicators against which future reductions of atmospherically emitted mercury can be measured. Completion of the study will result in large dataset which is compatible to those already existing in the State of Maine, and in the Adirondack region of New York. A concurrent EPA-sponsored sister project is underway which is directly measuring atmopsheric deposition of mercury across New England. The in-lake and biological mercury data may thus be linked to geographic patterns of atmospheric mercury deposition in Vermont and New Hampshire. The project will measure total mercury and total methylmercury (the toxic form of mercury) in surface sediments and waters of 90 randomly-selected Vermont and New Hampshire lakes. The same lakes will be tested for a variety of naturally occurring chemical constituents. A subset of these 90 lakes will be selected for mercury analysis in the follwoing biological compartments: large-bodied zooplankton, benthic macroinvertebrates, small (plankton-eating) yellow perch, large (fish-eating) yellow perch, and obligate piscivores such as loons, mergansers, and kingfishers. This project will also assess historical patterns of atmospheric mercury deposition to Vermont and New Hampshire lakes. This will be accomplished by analyzing mercury from radiometrically dated sediment cores of 13 study lakes. Recent studies from Minnesota, Maine, and the Adirondacks of New York suggest that mercury accretion to lake sediments has decreased in recent years. Preliminary unpublished data from this project may corroborate these findings.