Geogenic Sources of Benzene in Aquifers Used for Public Supply, California

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• 作者：Matthew K. Landon ; Kenneth Belitz
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2012
• 出版时间：August 21, 2012
• 年：2012
• 卷：46
• 期：16
• 页码：8689-8697
• 全文大小：435K
• 年卷期：v.46,no.16(August 21, 2012)
• ISSN：1520-5851

文摘

Statistical evaluation of two large statewide data sets from the California State Water Board鈥檚 Groundwater Ambient Monitoring and Assessment Program (1973 wells) and the California Department of Public Health (12鈥?17 wells) reveals that benzene occurs infrequently (1.7%) and at generally low concentrations (median detected concentration of 0.024 渭g/L) in groundwater used for public supply in California. When detected, benzene is more often related to geogenic (45% of detections) than anthropogenic sources (27% of detections). Similar relations are evident for the sum of 17 hydrocarbons analyzed. Benzene occurs most frequently and at the highest concentrations in old, brackish, and reducing groundwater; the detection frequency was 13.0% in groundwater with tritium <1 pCi/L, specific conductance >1600 渭S/cm, and anoxic conditions. This groundwater is typically deep (>180 m). Benzene occurs somewhat less frequently in recent, shallow, and reducing groundwater; the detection frequency was 2.6% in groundwater with tritium 鈮? pCi/L, depth <30 m, and anoxic conditions. Evidence for geogenic sources of benzene include: higher concentrations and detection frequencies with increasing well depth, groundwater age, and proximity to oil and gas fields; and higher salinity and lower chloride/iodide ratios in old groundwater with detections of benzene, consistent with interactions with oil-field brines.