Scientific Investigations Report 2007-5219
Certain ecosystem types, particularly wetlands, have environmental characteristics that can make them particularly sensitive to mercury inputs and that can result in large mercury concentrations in fish or other aquatic biota. To provide information needed to make effective management decisions to decrease human and wildlife exposure to methylmercury in northern prairie pothole wetlands, the U.S. Geological Survey, in cooperation with the North Dakota Department of Health, conducted a study to assess mercury and methylmercury concentrations in wetlands at the Lostwood National Wildlife Refuge (the Refuge) in northwest North Dakota. In April 2003 and 2004, water and bottom-sediment samples were collected from 44 individual wetlands that were classified as one of four wetland types. Many factors that may affect methylmercury production were considered in the study.
The prairie pothole wetlands at the Refuge had large ranges in major environmental characteristics. Hydrologic differences, most notably semiannual wetting and drying cycles, that are intrinsic to prairie pothole wetlands affected methylmercury concentrations. This likely resulted from the stimulation of anaerobic microbial activity following reflooding of soils, particularly soils containing substantial organic carbon. Among the four wetland types considered for this study, seasonal and semipermanent wetlands generally had the largest methylmercury concentrations. Regardless of wetland type, however, methylmercury concentrations at the Refuge are large in relation to reported concentrations for natural aquatic systems.
Posted November 2007
Sando, S.K., Krabbenhoft, D.P., Johnson, K.M., Lundgren, R.F., and Emerson, D.G., 2007, Mercury and methylmercury in water and bottom sediments of wetlands at Lostwood National Wildlife Refuge, North Dakota, 2003–04: U.S. Geological Survey Scientific Investigations Report 2007–5219, 66 p.
Description of Study Area
Wetland Sampling Site Selection
Collection, Processing, and Analysis of Water and Bottom-Sediment Samples
Collection, Processing, and Analysis of Quality-Assurance/Quality-Control Samples
Climatic Conditions Prior to Sample Collection
Mercury and Methylmercury in Water and Bottom Sediments
Wetland Water and Bottom-Sediment Sampling
Patterns in Occurrence of Mercury, Methylmercury, and Other Water-Quality Properties and Constituents
Mercury Constituents in Water and Bottom-Sediment Samples and Properties of Bottom-Sediment Samples
Water-Quality Properties and Constituents Measured at Time of Sample Collection
Major-Ion and Selected Trace-Element Constituents in Water Samples
Organic-Carbon Constituents in Water Samples
Relations Between Mercury Constituents and Other Properties and Constituents in Water
Summary and Conclusions
Supplement 1. Quality Assurance/Quality Control
Quality-Assurance/Quality-Control Data Collection
Supplement 2. Water-Quality Property and Constituent Values
Supplement 3. Major-Ion, Suspended-Solids, and Nonmercury Trace-Element Data for Water Samples
Supplement 4. Mercury and Organic-Carbon Data for Water and Bottom-Sediment Samples
Supplement 5. Analytical Results for Quality-Assurance/Quality-Control Field-Equipment Blank Samples
Supplement 6. Analytical Results and Relative Standard Deviations for Quality-Assurance/Quality-Control Replicate Samples for Sites 1, 19, 26, and 32.
|For additional information contact:
North Dakota Water Science Center Director
U.S. Geological Survey
821 East Interstate Avenue
ismarck, ND 58503-1199
World Wide Web: http://nd.water.usgs.gov/
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