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RADIUM IN MARYLAND COASTAL PLAIN GROUND WATER: AN EMERGING ISSUE RESULTING FROM A MULTI-AGENCY STUDY OF CARCINGENS IN WELL WATER
Citation:
Bolton, D. W., T H. Pheiffer, AND J. W. Grace. RADIUM IN MARYLAND COASTAL PLAIN GROUND WATER: AN EMERGING ISSUE RESULTING FROM A MULTI-AGENCY STUDY OF CARCINGENS IN WELL WATER. The Proceedings of the National Water Qualtiy Monitoring Council's National Monitoring Conference 2000, Monitoring for the Millennium, Austin, TX, April 25, 2000.
Description:
In 1997, radium-226 plus radium-228 concentrations as high as 66 picocuries per liter were detected in domestic well-water samples from the (Cretaceous) Potomac Group and Magothy Formation in Anne Arundel County, Maryland. Furthermore, radium-224 was found to be a major component of total radium. Additional sampling was conducted in 1998 in the upper Chesapeake Bay area in Maryland as part of a cooperative research effort involving the Maryland Department of Environment, the Maryland Department of Natural Resources, the U.S. Environmental Protection Agency, the U.S. Geological Survey, and local health departments. Samples were analyzed for radium-226, radium-228, gross alpha-particle activity (GAPA), and gross beta-particle activity (GBPA). The highest radionuclide concentrations were found in Anne Arundel County, although GPA exceeded 15 pCi/L (the federal drinking water standard) in one or more wells in most of the other counties. Radionuclide concentrations were negatively correlated with pH and positively correlated with total dissolved solids (particularly sodium and chloride). Ground-water radium and GAPA tended to be higher in the outcrop and updip areas of the Potomac Group and Magothy Formation, and lower in the downdip (confined) portions of the aquifers. Radium probably occurs naturally in the aquifer materials; however, mobilization of radium to ground water is apparently affected by both natural factors and human activity. Because radium-224 has a half-life of 3.64 days, it is necessary to measure GAPA within 3 days of sampling.