The toxic substances, including arsenic, selenium and strontium, were all found at levels higher than recommended levels in wells in and around the Barnett Shale, an important reservoir of natural gas in North Texas.
The study, led by Kevin Schug, professor of chemistry and biochemistry at the University of Texas (UT) at Arlington, took water samples from 100 private wells. Of these, 91 were taken from wells that were within a five kilometre radius of a natural gas drilling site, while another nine were taken from “reference areas” of more than 14 kilometres from a drilling site.
The highest levels of contaminants were discovered within three kilometres of natural gas wells. While many of the heavy metals identified in the samples are naturally present in groundwater, the researchers found that they were present at levels higher than historical average.