Uranium and Radon in Private Bedrock Well Water in Maine: Geospatial Analysis at Two Scales

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• 作者：Qiang Yang ; Paul Smitherman ; C. T. Hess ; Charles W. Culbertson ; Robert G. Marvinney ; Andrew E. Smith ; Yan Zheng
• 刊名：Environmental Science & Technology
• 出版年：2014
• 出版时间：April 15, 2014
• 年：2014
• 卷：48
• 期：8
• 页码：4298-4306
• 全文大小：450K
• 年卷期：v.48,no.8(April 15, 2014)
• ISSN：1520-5851

文摘

In greater Augusta of central Maine, 53 out of 1093 (4.8%) private bedrock well water samples from 1534 km² contained [U] >30 渭g/L, the U.S. Environmental Protection Agency鈥檚 (EPA) Maximum Contaminant Level (MCL) for drinking water; and 226 out of 786 (29%) samples from 1135 km² showed [Rn] >4,000 pCi/L (148 Bq/L), the U.S. EPA鈥檚 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鈥?0 km distance of granitic intrusions but do not show correlations with metamorphism at intermediate scales (10⁰鈭?0¹ km). This spatial association is confirmed by a high-density sampling (n = 331, 5鈥?0 samples per km²) at local scales (鈮?0^鈥? km) and the statewide sampling (n = 5857, 1 sample per 16 km²) at regional scales (10²鈥?0³ km). Wells located within 5 km of granitic intrusions are at risk of containing high levels of [U] and [Rn]. Approximately 48鈥?00鈥?3鈥?00 and 324鈥?00 people in Maine are estimated at risk of exposure to U (>30 渭g/L) and Rn (>4000 pCi/L) in well water, respectively.