A new study has found that liquid wastes from hydraulic fracturing, or "fracking," that was treated and released into local streams in Pennsylvania still contained elevated levels of salts and other contaminants, which could be dangerous to aquatic life and human health.
The study also reports high levels of radioactive materials in stream sediments at the disposal site. Published in the ACS journal Environmental Science & Technology, it states that the scientists recommend use of advanced treatment technologies to further remove the potentially harmful material.
Avner Vengosh, Nathaniel R. Warner and colleagues explain that although fracking technology has fueled a boom in U.S. oil and gas production, disposal of its wastewater remains a major challenge. It is 2 to 5 times as salty as seawater and contains substances that could harm the environment and humans. One of the options some oil and gas companies have is to send the waste to a site where it is treated and then released into local streams where it is diluted. The Duke team investigated how such a disposal practice would affect the environment.
The scientists tested the discharge and stream water samples both upstream and downstream from a wastewater disposal site in western Pennsylvania. They found that the treatment removed some of the potentially harmful contaminants from wastewater -- more than 90 percent of barium and radium, for instance. However, chloride and bromide levels were still high. In addition, they found that radium levels in stream sediments where the wastewater was discharged were still about "200 times greater than upstream and background sediments and above radioactive waste disposal threshold regulations, posing potential environmental risks of radium bioaccumulation in localized areas of shale gas wastewater disposal," the researchers state.
The authors acknowledge funding from the Park Foundation and the Duke University Nicholas School of the Environment.
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