National Water-Quality Assessment (NAWQA) Program
The NAWQA Program is studying mercury cycling in watersheds across the Nation to build an understanding of how natural features and human activities affect the transformation, transport, and bioaccumulation of mercury in stream ecosystems. As of August 2008, mercury was the second leading cause of stream impairment throughout the Nation USEPA 303(d) list). Methylmercury is a neurotoxin that is biomagnified in aquatic food webs so that piscivorous fish and wildlife, and humans that consume fish, are potentially at greater risk of exposure to methylmercury. USGS data and research may aid in the development of more rigorous models that relate water quality to mercury bioaccumulation, thereby enhancing capabilities for predicting mercury contamination in fish.
Our 2nd group of studies focused on small streams in the upper Hudson River Basin in the Adirondacks of New York State, and in the upper Edisto River Basin in the Coastal Plain of South Carolina. Our publications, including those resulting from collaboration with other scientists, are available for download from our Publications page. Detailed methods, data sets, and descriptions of study areas are available in the Methods and Data section of our Publications page.
Papers focused on the contrasting upper Hudson River and upper Edisto River basins. Biota: macroinvertebrates and fishes | influence of dietary carbon | Stream water: Spatial and seasonal variability | Intra- and inter-basin comparisons
Papers focused on the upper Hudson River basin: SUVA as an indicator | Landscape controls | Mobilization of mercury and dissolved organic carbon
Papers focused on the upper Edisto River basin: Climate change and watershed mercury export | Shallow groundwater mercury supply | Hydrology and methylmercury availability | Flood hydrology and methylmercury | Dynamic modeling
How Mercury Flows Downstream features three papers on mercury cycling in stream ecosystems from our first group of studies, in Oregon, Wisconsin, and Florida.