title: Uranium and radon in private bedrock well water in Maine: geospatial analysis at two scales.
abstract: In greater Augusta of central Maine, 53 out of 1093 (4.8%) private bedrock well water samples from 1534 km(2) contained [U] >30 μg/L, the U.S. Environmental Protection Agency's (EPA) Maximum Contaminant Level (MCL) for drinking water; and 226 out of 786 (29%) samples from 1135 km(2) showed [Rn] >4,000 pCi/L (148 Bq/L), the U.S. EPA's Alternative MCL. Groundwater pH, calcite dissolution and redox condition are factors controlling the distribution of groundwater U but not Rn due to their divergent chemical and hydrological properties. Groundwater U is associated with incompatible elements (S, As, Mo, F, and Cs) in water samples within granitic intrusions. Elevated [U] and [Rn] are located within 5-10 km distance of granitic intrusions but do not show correlations with metamorphism at intermediate scales (10(0)-10(1) km). This spatial association is confirmed by a high-density sampling (n = 331, 5-40 samples per km(2)) at local scales (≤10(-1) km) and the statewide sampling (n = 5857, 1 sample per 16 km(2)) at regional scales (10(2)-10(3) km). Wells located within 5 km of granitic intrusions are at risk of containing high levels of [U] and [Rn]. Approximately 48 800-63 900 and 324 000 people in Maine are estimated at risk of exposure to U (>30 μg/L) and Rn (>4000 pCi/L) in well water, respectively.
authors.affiliation: Columbia University , Lamont-Doherty Earth Observatory, 61 route 9W, Palisades, New York 10964, United States.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Yang
authors.forename: Paul
authors.initials: P
authors.lastname: Smitherman
authors.forename: C T
authors.initials: CT
authors.lastname: Hess
authors.forename: Charles W
authors.initials: CW
authors.lastname: Culbertson
authors.forename: Robert G
authors.initials: RG
authors.lastname: Marvinney
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Smith
authors.forename: Yan
authors.initials: Y
authors.lastname: Zheng
mesh_terms: D060766:Drinking Water / Q000737:chemistry; D005843:Geography; D019015:Geologic Sediments / Q000737:chemistry*; D008281:Maine; D011886:Radon / Q000032:analysis*; D018570:Risk Assessment; D014481:United States; D014501:Uranium / Q000032:analysis*; D014875:Water Pollutants, Radioactive / Q000032:analysis*; D060986:Water Wells / Q000737:chemistry*
chemical_list: D060766:Drinking Water; D014875:Water Pollutants, Radioactive; D014501:Uranium; D011886:Radon