Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing
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Directional drilling and hydraulic-fracturing technologies are dramatically increasing natural-gas extraction. In aquifers overlying the Marcellus and Utica shale formations of northeastern Pennsylvania and upstate New York, we document systematic evidence for methane contamination of drinking water associated with shale gas extraction. In active gas-extraction areas (one or more gas wells within 1 km), average and maximummethane concentrations in drinking-water wells increased with proximity to the nearest gas well and were 19.2 and 64 mg CH4 L−1 (n ¼ 26), a potential explosion hazard; in contrast, dissolved methane samples in neighboring nonextraction sites (no gas wells within 1 km) within similar geologic formations and hydrogeologic regimes averaged only 1.1 mgL−1 (P < 0.05; n ¼ 34). Average δ13C-CH4 values of dissolved methane in shallow groundwater were significantly less negative for active than for nonactive sites (−37 7‰ and −54 11‰, respectively; P < 0.0001). These δ13C-CH4 data, coupled with the ratios of methane-to-higher-chain hydrocarbons, and δ2H-CH4 values, are consistent with deeper thermogenic methane sources such as the Marcellus and Utica shales at the active sites and matched gas geochemistry from gas wells nearby. In contrast, lower-concentration samples from shallow groundwater at nonactive sites had isotopic signatures reflecting a more biogenic or mixed biogenic/thermogenic methane source. We found no evidence for contamination of drinking-water samples with deep saline brines or fracturing fluids. We conclude that greater stewardship, data, and—possibly—regulation are needed to ensure the sustainable future of shale-gas extraction and to improve public confidence in its use.
Published Version (Please cite this version)10.1073/pnas.1100682108
Publication InfoOsborn, Stephen G; Vengosh, Avner; Warner, Nathaniel R; & Jackson, Robert B (2011). Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing. 10.1073/pnas.1100682108. Retrieved from https://hdl.handle.net/10161/4642.
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Adjunct Professor of Earth & Ocean Sciences
Robert B. Jackson is the Nicholas Chair of Global Environmental Change in the Earth and Ocean Sciences Division of the Nicholas School of the Environment and a professor in the Biology Department. His research examines how people affect the earth, including studies of the global carbon and water cycles, biosphere/atmosphere interactions, energy use, and global change. Rob Jackson received his B.S. degree in Chemical Engineering from Rice University (1983). He worked four years for the Dow
Nicholas Distinguished Professor of Environmental Quality
My research aims to link environmental geochemistry and isotope hydrology in order to trace the sources and mechanisms of water contamination and relationships with human health. Current research includes global changes of the chemical and isotopic compositions of water resources due to human intervention and contamination, salinization of water resources in the Middle East and Northern Africa, naturally occurring contaminants (arsenic, fluoride, boron) and radioactivity in water resources, the
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