Chemists have found signs of contamination in well water samples collected throughout the Eagle Ford Shale region in Texas.

Scientists found evidence of dissolved gases as well as spikes in levels of volatile organic compounds in well water samples. They also found unusual chloride-bromide ratios. The evidence suggests the contamination is a result of industrial or agricultural activity in the region.

"The infrequent detection of volatile organic compounds in the groundwater overlying the Eagle Ford Shale is certainly good news for citizens," Kevin Schug, a chemist at the University of Texas at Arlington, said in a news release. "However, there were instances of abnormalities on the water that we cannot quite explain."

Some water samples revealed high bromide levels, which is indicative of contamination events. Other water samples featured effervescence, a sign of the presence of dissolved hydrocarbon gases. Several water samples collected near oil and gas extraction sites featured heightened levels of volatile organic compounds.

"The next step in this research is to further characterize what these gases and chemicals are attributed to," Schug added. "Hopefully a closer collaboration with industry to gain a more intimate knowledge of the chemicals used during shale energy extraction will allow us to better assess whether or not unconventional oil and gas development is having a significant impact on groundwater quality in the south Texas region."

The latest findings were published in the journal Science of the Total Environment.

Schug is the director of UTA's CLEAR lab, short for Collaborative Laboratories for Environmental Analysis and Remediation. CLEAR lab scientists are also working on ways to reduce contamination events at oil well pad sites.

"CLEAR continues to provide reliable information to the scientific community, industry and the public about the potential effects of large-scale unconventional oil and gas development on the environment," said Frederick MacDonnell, chair of department of chemistry and biochemistry at UTA. "This is a service we can provide to all these different sectors."