Highly toxic gas due to shale gas extraction

(Some people living near shale gas wells are at risk of being affected by the contamination of drinking water by gases from shale gas extraction , according to a study. just led by Duke University.

Scientists analyzed 141 water samples from households across the northeastern basin of the Marcellus- rich shale of Pennsyvania state.

The analytical results show that methane concentration is 6 times higher and the concentration of ethane is 23 times higher in families wells within 1km of a shale gas well. Propane was also detected in 10 samples, all of which were from households within 1 km of the drill hole.

"Data on methane, ethane and propane, and new evidence from hydrocarbon and helium components, all showed that boreholes are affecting the water supply of households," said Dr. Robert B. Jackson, Professor Nicholas at Duke's School of Environmental Sciences said, 'In a few cases, gas is even the same as Marcellus' - probably because of poor well construction.'

'Ethane and propane data are remarkable , ' Jackson said, 'because there is no biological source of ethane and propane in this area and Marcellus shale gas contains high concentrations of both of these gases, and high. more about the concentration compared to the gases of the Upper Body ' found in Marcellus shale areas.

Scientists have conducted tests to find out what are the factors that lead to this situation, including factors such as terrain, distance to wells and distance to the geological strata.'The distance to gas wells is the most important factor affecting the concentration of gas in the drinking water that we sampled' , Jackson said.

Photo: nbcnews.com

The research team has published an online discovery in the Proceedings of the National Academy of Sciences magazine.

Shale gas extraction - a process that includes horizontal drilling and hydraulic fracturing - has prompted concerns in recent years about polluting drinking water near the mining area.

The previous two studies led by Duke gave direct evidence of methane contamination in wells located near shale gas boreholes in northeast Pennsylvania, as well as possible hydraulic bonds between water. Deep sea and shallow aquifers. The third study, conducted with US geological survey scientists, found no evidence of contaminated drinking water due to shale gas production in Arkansas. No studies found evidence of current contamination due to hydraulic fracture fluid.

This new study is the first to provide direct evidence of ethane and propane pollution.

'Our studies demonstrate that the integrity of gas wells, as well as regional and regional geological changes, play important roles in determining the risks of underground impacts from development of shale gas. Therefore, it is necessary to consider carefully before the drilling process begins , " warned Avner Vengosh, professor of geological chemistry and water quality at Nicholas's Duke School.

'These new data reinforce our previous observations of leaking gases polluting domestic wells in some Marcellus shale gas extraction areas. The question is what is happening in other shale gas basins' , Vengosh said.

"Data on helium in this study is the new tool we have developed to determine pollution using rare gas geochemistry," said Thomas H. Darrah, a geological research scientist, also from Nicholas. "The new tools allow us to identify and monitor contaminants with high certainty through multiple lines of evidence," Duke said .

The co-authors of this new study are Nathaniel Warner, Adrian Down, Kaiguang Zhao and Jonathan Karr, all of whom are from Duke University; Robert Poreda of Rochester University, and Stephen Osborn of California State Polytechnic University. Duke's Nicholas School of Environment and Duke University's Global Transformation Center funded this study.

Shale is fine-grained sedimentary rock whose original constituents are clay or mud minerals. It is characterized by thin plates broken by irregular curvature, often brittle and generally parallel to the bottom plane difficult to distinguish.

Since the 70s of the twentieth century, to ensure energy security, the US government has been increasingly interested in finding gas in shale. The US government conducted exploration work and discovered four large schist structures including Barnett, Haynesville, Fayetteville and Marcellus distributed over tens of thousands of square kilometers with huge gas reserves.