Naturally occurring radium (Ra) in home drinking‐water wells in the Sandhills region of South Carolina, USA: Can high concentrations be predicted?. Issue 4 (14th June 2017) - Schrag, Jeffrey M.
Abstract: A strong relationship exists between concentrations of several principal constituents of water chemistry and naturally occurring radium in water from home wells in the large Sandhills region of the inner coastal plain of South Carolina, United States, an area of common radium problems (75% (21 of 28 of randomly selected wells in the main study area were above the U.S. Environmental Protection Agency (USEPA) maximum contaminant level (MCL): 5 picocuries per liter for 226 Ra plus 228 Ra). Ingested radioactive radium is potentially carcinogenic, and water far above the MCL occurs in places. One focus here was to determine if elevated radium concentrations can reliably be predicted using more easily measured characteristics of water chemistry. The initial phase investigated (1) concentrations of radium in well water within a smaller (~10 km radius) test area of known common problems plus (2) the associated water chemistry. This revealed a correlation between elevated radium and raised electrical conductance, total dissolved solids, calcium, nitrate, magnesium, hardness, and lowered pH. All are potentially useful screening tools for the many other rural home wells of this region. Natural groundwater in these highly leached sands is of very low dissolved salt content of all types, and local human influence on geochemistry is thus indicated. Predictive utility was examined by two additional series of wells (1) of higher radium contamination or (2) of elevated calcium concentration, both identified from file data. Higher radium wells were retested for water chemistry and higher calcium wells for radium content. Overall, a similar association between radium and water chemistry was observed. Plain Language Summary: Naturally occurring dissolved radium has been detected at elevated concentrations in groundwater from several regions of South Carolina and is a known human carcinogen. This study investigated water chemistry in drinking‐water wells located in the Sandhills region of the inner coastal plain of South Carolina in an attempt to identify possible important indicators for excessive dissolved radium in groundwater. The objectives of the study were to develop a predictor model based on the water chemistry associations that could ultimately be used as an effective yet inexpensive screening method more quickly than a direct radium analysis. Key Points: To determine if elevated radium concentrations can reliably be predicted using more easily measured characteristics of water chemistry Develop a screening tool for rural home wells Develop a predictor model for estimating radium concentrations in rural home wells