TY - JOUR
T1 - Big Groundwater Data Sets Reveal Possible Rare Contamination Amid Otherwise Improved Water Quality for Some Analytes in a Region of Marcellus Shale Development
AU - Wen, Tao
AU - Niu, Xianzeng
AU - Gonzales, Matthew
AU - Zheng, Guanjie
AU - Li, Zhenhui
AU - Brantley, Susan L.
N1 - Funding Information:
Funding derived from the National Science Foundation IIS-16-39150 to S.L.B. and Z.L. We thank Terry Engelder and David Yoxtheimer (Penn State University) for insights, Fei Wu and Alison Herman (Penn State University) for technical support, Bruce Lindsey (USGS) and Seth Pelepko and Stew Beattie (PA DEP) for access and help with data. We thank the editor for handling this paper as well as four anonymous reviewers for their insightful and thorough reviews.
Publisher Copyright:
© 2018 American Chemical Society.
PY - 2018/6/19
Y1 - 2018/6/19
N2 - Eleven thousand groundwater samples collected in the 2010s in an area of Marcellus shale-gas development are analyzed to assess spatial and temporal patterns of water quality. Using a new data mining technique, we confirm previous observations that methane concentrations in groundwater tend to be naturally elevated in valleys and near faults, but we also show that methane is also more concentrated near an anticline. Data mining also highlights waters with elevated methane that are not otherwise explained by geologic features. These slightly elevated concentrations occur near 7 out of the 1,385 shale-gas wells and near some conventional gas wells in the study area. For ten analytes for which uncensored data are abundant in this 3,000 km2 rural region, concentrations are unchanged or improved as compared to samples analyzed prior to 1990. Specifically, TDS, Fe, Mn, sulfate, and pH show small but statistically significant improvement, and As, Pb, Ba, Cl, and Na show no change. Evidence from this rural area could document improved groundwater quality caused by decreased acid rain (pH, sulfate) since the imposition of the Clean Air Act or decreased steel production (Fe, Mn). Such improvements have not been reported in groundwater in more developed areas of the U.S.
AB - Eleven thousand groundwater samples collected in the 2010s in an area of Marcellus shale-gas development are analyzed to assess spatial and temporal patterns of water quality. Using a new data mining technique, we confirm previous observations that methane concentrations in groundwater tend to be naturally elevated in valleys and near faults, but we also show that methane is also more concentrated near an anticline. Data mining also highlights waters with elevated methane that are not otherwise explained by geologic features. These slightly elevated concentrations occur near 7 out of the 1,385 shale-gas wells and near some conventional gas wells in the study area. For ten analytes for which uncensored data are abundant in this 3,000 km2 rural region, concentrations are unchanged or improved as compared to samples analyzed prior to 1990. Specifically, TDS, Fe, Mn, sulfate, and pH show small but statistically significant improvement, and As, Pb, Ba, Cl, and Na show no change. Evidence from this rural area could document improved groundwater quality caused by decreased acid rain (pH, sulfate) since the imposition of the Clean Air Act or decreased steel production (Fe, Mn). Such improvements have not been reported in groundwater in more developed areas of the U.S.
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U2 - 10.1021/acs.est.8b01123
DO - 10.1021/acs.est.8b01123
M3 - Article
C2 - 29783843
AN - SCOPUS:85047471984
SN - 0013-936X
VL - 52
SP - 7149
EP - 7159
JO - Environmental Science & Technology
JF - Environmental Science & Technology
IS - 12
ER -