Researchers analyzed well water samples from counties overlying the Marcellus shale formation in Pennsylvania and New York. Accelerated gas drilling and hydrofracking in the region in recent years has fueled concerns about well-water contamination by methane and fracking fluids, which contain a proprietary mix of chemicals that companies often don't disclose. Above, a hydrofracking protest in Albany, NY, on April 11, 2011. (Credit: Bennett V/Flickr)
DUKE (US) — Researchers found high levels of leaked methane in well water collected near shale-gas drilling and hydrofracking sites in Pennsylvania.
Hydraulic fracturing, also called hydrofracking or fracking, involves pumping water, sand and chemicals deep underground into horizontal gas wells at high pressure to crack open hydrocarbon-rich shale and extract natural gas.
The scientists collected and analyzed water samples from 68 private groundwater wells across five counties in northeastern Pennsylvania and New York. Findings are reported this week in the Early Edition of the Proceedings of the National Academy of Sciences.
“At least some of the homeowners who claim that their wells were contaminated by shale-gas extraction appear to be right,” says Robert Jackson, a Duke University professor.
The study found no evidence of contamination from chemical-laden fracking fluids, which are injected into gas wells to help break up shale deposits, or from “produced water,” wastewater that is extracted back out of the wells after the shale has been fractured.
“We found measurable amounts of methane in 85 percent of the samples, but levels were 17 times higher on average in wells located within a kilometer of active hydrofracking sites,” says Stephen Osborn, postdoctoral research associate. The contamination was observed primarily in Bradford and Susquehanna counties in Pennsylvania.
Water wells farther from the gas wells contained lower levels of methane and had a different isotopic fingerprint.
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November 9, 2011 
