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Principal aquifers can contribute radium to sources of drinking water under certain geochemical conditions

Fact Sheet 2010-3113

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Abstract

What are the most important factors affecting dissolved radium concentrations in principal aquifers used for drinking water in the United States? Study results reveal where radium was detected and how rock type and chemical processes control radium occurrence. Knowledge of the geochemical conditions may help water-resource managers anticipate where radium may be elevated in groundwater and minimize exposure to radium, which contributes to cancer risk. Summary of Major Findings: * Concentrations of radium in principal aquifers used for drinking water throughout the United States generally were below 5 picocuries per liter (pCi/L), the U.S. Environmental Protection Agency (USEPA) maximum contaminant level (MCL) for combined radium - radium-226 (Ra-226) plus radium-228 (Ra-228) - in public water supplies. About 3 percent of sampled wells had combined radium concentrations greater than the MCL. * Elevated concentrations of combined radium were more common in groundwater in the eastern and central United States than in other regions of the Nation. About 98 percent of the wells that contained combined radium at concentrations greater than the MCL were east of the High Plains. * The highest concentrations of combined radium were in the Mid-Continent and Ozark Plateau Cambro-Ordovician aquifer system and the Northern Atlantic Coastal Plain aquifer system. More than 20 percent of sampled wells in these aquifers had combined radium concentrations that were greater than or equal to the MCL. * Concentrations of Ra-226 correlated with those of Ra-228. Radium-226 and Ra-228 occur most frequently together in unconsolidated sand aquifers, and their presence is strongly linked to groundwater chemistry. * Three common geochemical factors are associated with the highest radium concentrations in groundwater: (1) oxygen-poor water, (2) acidic conditions (low pH), and (3) high concentrations of dissolved solids.

Additional Publication Details

Publication type:
Report
Publication Subtype:
USGS Numbered Series
Title:
Principal aquifers can contribute radium to sources of drinking water under certain geochemical conditions
Series title:
Fact Sheet
Series number:
2010-3113
Year Published:
2012
Language:
English
Publisher:
U.S. Geological Survey
Publisher location:
Reston, VA
Contributing office(s):
New Jersey Water Science Center
Description:
6 p.
Time Range Start:
1990-01-01T12:00:00
Time Range End:
2005-12-31T12:00:00
Country:
United States