Elevated levels of metals found in water in Barnett Shale

ARLINGTON — Researchers at the University of Texas at Arlington say there are elevated levels of arsenic and other heavy metals close to natural gas extraction sites in the Barnett Shale area of North Texas, according to a news release from the school Friday.

Several scenarios — including disturbances from hydraulic fracturing, lower water tables from drought, removal of water used for fracturing or industrial accidents such as faulty gas well casings — could release the dangerous compounds into shallow groundwater.

“This study alone can’t conclusively identify the exact causes of elevated levels of contaminants in areas near natural gas drilling, but it does provide a powerful argument for continued research,” said Brian Fontenot, the lead author on the new paper.

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Arsenic, barium, strontium and selenium occur naturally at low levels in groundwater. But the release says hydraulic fracturing activities could elevate their levels.

The results from the peer-reviewed study were published online by the journal Environmental Science & Technology.

Elevated levels for most of the metals were not found outside active drilling areas or outside the shale.

Fracking, or hydraulic fracturing, uses chemicals along with water under high pressure to crack open rock formations and release oil and natural gas.
Samples were gathered from 100 private water wells of varying depths within a 13-county area in or near the Barnett Shale during four months in summer and fall of 2011.

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Additionally, the paper recommended further research on methanol and ethanol levels in water wells after 29 of the 100 wells in the study contained methanol. The highest concentrations were in the areas of hydraulic fracturing activity.

The samples were compared to historical data on water wells from the Texas Water Development Board groundwater database for 1989-1999, before natural gas drilling activity ramped up.