Show simple item record Osborn, Dr Stephen Vengosh, Avner Warner, Nathaniel R. Jackson, Robert 2011-07-15T18:45:06Z 2011-07-15T18:45:06Z 2011-05-09
dc.identifier.citation Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing, PNAS, May 2011, en_US
dc.description.abstract 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. en_US
dc.description.sponsorship We gratefully acknowledge financial support from Fred and Alice Stanback to the Nicholas School of the Environment and from the Duke Center on Global Change. en_US
dc.language.iso en_US en_US
dc.publisher National Academy of Sciences en_US
dc.relation.isversionof en_US
dc.title Methane contamination of drinking water accompanying gas-well drilling and hydraulic fracturing en_US
dc.type Article en_US so56 en_US vengosh en_US nrw en_US jackson en_US

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