A Marcellus Shale gas well operation in Scott Township, Pennsylvania. Photo credit: wcn247/Flickr Creative Commons A Marcellus shale gas well operation in Scott Township, Pennsylvania. Photo credit: wcn247/Flickr Creative Commons At least one aspect of fracking’s risks to drinking water became a little clearer this week. A study led by Rob Jackson of Duke University’s Nicholas School of the Environment, and published in the Proceedings of the National Academy of Sciences, found that drinking water wells located within 1 kilometer of a shale gas well in a region of northeastern Pennsylvania are at high risk of contamination with methane. Fracking, shorthand for hydraulic fracturing, is the process of blasting water mixed with sand and chemicals deep underground at high pressure so as to fracture shale rock and release the gas it holds. Colorless, odorless, and highly flammable, methane is the primary component of natural gas. It is not regulated as a drinking water contaminant, but it poses potential health and safety hazards. If the gas builds up in a basement or other confined space, for example, it can set off an explosion or start a fire. If breathed in high enough concentrations, it can cause dizziness, headaches and nausea. The risks of long-term exposure and of secondary water quality changes due to high levels of dissolved methane are not known. The research team analyzed 141 drinking water wells in northeastern Pennsylvania’s gas-rich Marcellus shale region and detected methane in 82 percent of them. For homes within 1 kilometer of a gas well, the average methane concentration was six times higher than in water wells located further away. Nearly 1 in 11 of the household wells analyzed had methane concentrations above the threshold level set by the U.S. Department of Interior for immediate remediation; all but one of those drinking water wells was within 1 kilometer of an active shale gas well. By analyzing the isotopic signature of the gases, Jackson’s team determined that the methane found in the drinking water was of fossil origin, not from current biological activity. The presence of ethane and propane, constituents of natural gas that are not produced by microbes, also signaled that the contamination was coming from nearby fracking operations. Ethane was detected in 30 percent of the home water wells sampled, and concentrations of this gas were 23 times higher on average for homes less than one kilometer from a fracking well. “Overall, our data suggest that some homeowners living
Posted on: Sat, 29 Jun 2013 20:52:20 +0000
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