National Water-Quality Assessment (NAWQA) Project
USGS mercury stream studies are implemented through the National Water-Quality Assessment (NAWQA) Program (a map can be accessed at the NAWQA Web site at http://water.usgs.gov/nawqa). In 1991, NAWQA began evaluating the quality of streams, ground water, and aquatic ecosystems in 51 major river basins and aquifer systems (known as "Study Units") across the Nation. The assessments characterize the ambient water resource—the source of about 60 percent of the Nation's drinking water and water for industrial, irrigation, and recreational uses. During its first decade, NAWQA made baseline assessments of pesticides, nutrients, volatile organic compounds, trace elements, dissolved solids, and radon in streams and ground water, as well as the condition of aquatic habitats and fish, insect, and algal communities. These findings are described in hundreds of reports (access NAWQA Web site above).
In the current decade (2002-2012), 42 of the Study Units will be reassessed to determine trends at many of the streams and ground-water monitoring sites; fill critical gaps in characterizing water-quality conditions; and build upon earlier NAWQA findings that show how natural features and human activities affect water quality and aquatic ecosystems. Mercury is one of five national priority topics addressed in the current decade of NAWQA studies. The other topics include effects of urbanization on stream ecosystems; ecological effects of nutrient enrichment; transport of contaminants to public-supply wells; and sources, transport, and fate of agricultural chemicals.
The NAWQA work is enhanced through research conducted by the USGS Toxic Substances Hydrology (TOXICs) Program, National Research Program (NRP), and various programs within the USGS Geology and Biology disciplines. This collaborative research largely focuses on chemical and biological processes controlling mercury transport, cycling, and biomagnification in stream ecosystems. Specifically, the different programs provide the following expertise:
Toxic Substances Hydrology Program (TOXICs)—Mercury cycling; chemical transformations and physical partitioning of mercury; state-of-the-art analytical methods.
National Atmospheric Deposition Program/National Trends Network—is a nationwide network of precipitation monitoring sites.
National Research Program—Microbial and chemical reaction rates (including sulfate reduction and mercury methylation and demethylation); mercury bioaccumulation.
Programs in the USGS Geology Discipline—Mercury methylation as it relates to sulfur geochemical cycling and sources.
Programs in the USGS Biology Discipline—Effects of mercury on fish health, including reproductive success, hormone levels, and genetic damage; occurrence of mercury in fish-eating birds. See especially the Contaminant Biology Program's mercury page.