Nitric oxide bioactivity and oxygen delivery following blood transfusions

Shale gas comprises an increasing fraction of the US natural gas supply, but the environmental implications of shale gas extraction—a process that includes horizontal drilling and hydraulic fracturing—remain uncertain. Expanding their previous study of methane gas contamination in private drinking water wells near active drilling operations in the Marcellus shale region of northeastern Pennsylvania and southeastern New York, Robert Jackson et al. (pp. 11250–11255) analyzed the concentrations and isotopic signatures of methane, ethane, and propane in 141 wells in the area. The authors report that 82% of the wells analyzed contained methane; on average, methane concentrations were six times higher for homes located less than 1 km from drilling sites than for homes farther away. Concentrations of ethane and propane were also high for homes located within 1 km of drilling sites. Furthermore, the authors found that distance to gas wells was the most significant factor to influence drinking water methane and ethane concentrations. In some cases, the authors report, the isotopic signatures and relative proportions of the gases in drinking water were characteristic of a Marcellus-like source. The findings suggest that some homes located within 1 km of Marcellus gas wells might have drinking water contaminated with stray gases, according to the authors. — N.Z.