Methane leaks are contaminating drinking
water near shale gas drilling sites in the eastern United States,
scientists said Tuesday, placing a further question mark over this
fast-growing energy source.
Scientists tested water samples taken from 68
private wells in five counties in Pennsylvania and New York to explore
accusations that hydraulic fracturing — a contested technique to
extract shale gas nicknamed “fracking” — contaminated groundwater.
Methane was found in 85% of the samples, and at sites within a kilometre
of active hydraulic-fracturing operations, levels were 17 times higher
than in wells far from such operations, said the study by researchers at
Duke University in North Carolina.
“In these rural areas, almost everybody has a well. They are using the
groundwater for some purpose — they are using it for drinking, for
their livestock, for agriculture,” lead author Stephen Osborn said.
However, little is known about the health impacts of consuming methane in drinking water. “We were surprised, and we have spoken with many health officials,” he said. “There is really no literature that addresses that particular issue —
the physiological response — is methane really non-reactive in the
body? What are the effects of consuming high concentrations of methane?”
The paper found no evidence of contamination from the chemicals used to
fracture the rock or from “produced” water — the wastewater that
emerges from the wells after the shale has been fractured. Shale gas is found in dense sedimentary rock which is fractured by large
volumes of water, sand and chemicals that are piped in horizontally at
very high pressure.
within a few days, along with significant amounts of methane, which
comprises the bulk of the shale gas.
The gas is enjoying a boom in North America and Europe, buoyed by high
prices and fears over the political risks of imported fossil fuels. Opponents say the technique is environmentally destructive because the
methane can contaminate groundwater and, if leaked to the air, add to
the greenhouse effect.
“Definitely natural gas is cleaner than coal but if you do it without
regulation or without careful monitoring, you might harm the
environment,” said co-author Avner Vengosh, also of Duke University.
“There is no really comprehensive oversight of what is going on. There is not enough scientific research,” he added. “We are just revealing something that should have been revealed long ago
before the boom took place. In some places it might be too late.”
The study, published on Monday in the peer-reviewed journal Proceedings
of the National Academy of Sciences (PNAS), said the methane sampled
near the fracking sites had an isotopic fingerprint that pointed to its
Water from wells farther from the gas sites had lower levels of methane and a different isotopic signature. As a gas, methane is flammable and can cause suffocation.
In April, scientists from New York’s Cornell University found that
current extraction techniques meant that shale gas carried a greater
carbon footprint than oil, coal and conventional gas over at least a
According to the US Department of Energy, total domestic production of
natural gas will grow by 20% by 2035. Shale gas alone will increase its
share of production from 16% in 2009 to 45% in 2035. — Sapa-AFP