On its own, a study by researchers at the University of Texas at Arlington doesn’t prove a whole lot about the presence, in some cases even dangerous levels, of heavy metals in groundwater near Barnett Shale natural gas drilling sites.The study shows reason to take notice of its findings. It shows reasons for more scientific investigation of its findings.That’s significant. Let’s hope the further investigation takes place.The drilling industry was quick to question the peer-reviewed study report, an online version of which was published Thursday by the journal Environmental Science & Technology.That’s significant, too. The study’s methodology is open to question in some parts. One of the reasons things like this get published is to allow critics to examine and respond to it.The study tested samples from 100 private water wells in and near the Barnett Shale. It showed elevated levels of heavy metals such as arsenic, selenium and strontium in areas closest to drilling sites.These contaminants exist naturally throughout much of the area, but elevated presence near drilling begs for explanation.Brian Fontenot, a UT Arlington researcher with a doctorate in quantitative biology and the study report’s lead author, said in a news release that the findings “can’t conclusively identify the exact causes” of the contamination, “but it does provide a powerful argument for continued research.”Steve Everley, national spokesman for Energy in Depth, an outreach campaign by the Independent Petroleum Association of America, noted in an online post that some experts say the testing in the UTA study did not include sufficient control samples (only nine samples out of 100 were from outside active drilling areas).Everley also pointed out that some news stories about the study results included headlines linking it to “fracking,” or hydraulic fracturing of wells. The study did not find the chemicals normally used in the fracking process in its well samples.He also focused on the researchers’ selection of testing sites. They issued a news release and chose from among those wells whose owners responded. Not exactly a scientific sampling.Still, the troubling contaminants were found, some at levels exceeding EPA safety standards for drinking water.Many people who live on or around the Barnett Shale would like to know how those contaminants got there.