Hydrofracking protest in Albany, NY, on April 11, 2011.
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.
DURHAM, US: 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.
“We found measurable amounts of methane in 85 per cent of the samples, but levels were 17 times higher on average in wells located within a kilometer of active hydrofracking sites,” said Stephen Osborn, Postdoctoral Research Associate. The contamination was observed primarily in Bradford and Susquehanna counties in Pennsylvania.
“Methane is CH4. By using carbon and hydrogen isotope tracers we could distinguish between thermogenic methane, which is formed at high temperatures deep underground and is captured in gas wells during hydrofracking, and biogenic methane, which is produced at shallower depths and lower temperatures,” said Avner Vengosh, Professor of geochemistry and water quality. Biogenic methane is not associated with hydrofracking.
“Methane in water wells within a kilometer had an isotopic composition similar to thermogenic methane. Outside this active zone, it was mostly a mixture of the two,” said Vengosh.
The scientists confirmed their finding by comparing the dissolved gas chemistry of water samples to the gas chemistry profiles of shale-gas wells in the region, using data from the Pennsylvania Department of Environmental Protection.
Methane is flammable and poses a risk of explosion. In high concentrations, it can cause asphyxiation. Little research has been conducted on the health effects of drinking methane-contaminated water and methane isn’t regulated as a contaminant in public water systems under the EPA’s National Primary Drinking Water Regulations.
Shale gas comprises about 15 per cent of natural gas produced in the United States. The Energy Information Administration estimates it will make up almost half of the nation’s production by 2035.
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