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Title: Chemical and isotope compositions of shallow groundwater in areas impacted by hydraulic fracturing and surface mining in the Central Appalachian Basin, Eastern United States

Here, hydraulic fracturing of shale deposits has greatly increased the productivity of the natural gas industry by allowing it to exploit previously inaccessible reservoirs. Previous research has demonstrated that this practice has the potential to contaminate shallow aquifers with methane (CH 4) from deeper formations. This study compares concentrations and isotopic compositions of CH 4 sampled from domestic groundwater wells in Letcher County, Eastern Kentucky in order to characterize its occurrence and origins in relation to both neighboring hydraulically fractured natural gas wells and surface coal mines. The studied groundwater showed concentrations of CH 4 ranging from 0.05 mg/L to 10 mg/L, thus, no immediate remediation is required. The δ 13C values of CH 4 ranged from 66‰ to 16‰, and δ 2H values ranged from –286‰ to –86‰, suggesting an immature thermogenic and mixed biogenic/thermogenic origin. The occurrence of CH 4 was not correlated with proximity to hydraulically fractured natural gas wells. Generally, CH 4 occurrence corresponded with groundwater abundant in Na +, Cl , and HCO 3 , and with low concentrations of SO 4 –2. The CH 4 and SO 4 –2 concentrations were best predicted by the oxidation/reduction potential of the studied groundwater. CH 4more » was abundant in more reducing waters, and SO 4 –2 was abundant in more oxidizing waters. Additionally, groundwater in greater proximity to surface mining was more likely to be oxidized. This, in turn, might have increased the likelihood of CH 4 oxidation in shallow groundwater.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [1]
  1. The Univ. of Tennessee, Knoxville, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Applied Geochemistry
Additional Journal Information:
Journal Volume: 71; Journal Issue: C; Journal ID: ISSN 0883-2927
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
Work for Others (WFO); USDOE
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; methane; groundwater; isotopes; hydraulic fracturing; surface mining
OSTI Identifier:
1328326