Industry has made efforts to reuse or to transport shale gas wastewater to deep injection wells, but wastewater is still discharged into the environment, after being treated, in some states.
In western Pennsylvania, water that comes from Marcellus shale is naturally high in salinity and radioactivity but a new Duke study examined the quality of shale gas wastewater resulting from hydraulic fracturing and found that the stream water above and below the Josephine Brine Treatment Facility disposal site that is derived from the Marcellus shale gas flowback water showed elevated levels of radioactivity, salts and metals.
High concentrations of some salts and metals were also observed in the stream water.
They also analyzed stream-bottom sediments for radium isotopes that are typically found in Marcellus wastewater and found that the facility's treatment process significantly reduced radium and barium levels in the wastewater but that the amount of radioactivity that has accumulated in the river sediments, natural or not, still exceeds thresholds for safe disposal of radioactive materials.
Credit and link:
Environmental Science&Technology October 2, 2013 DOI: 10.1021/es402165b
"Radium levels were about 200 times greater in sediment samples collected where the Josephine Brine Treatment Facility discharges its treated wastewater into Blacklick Creek than in sediment samples collected just upstream of the plant," said Avner Vengosh, professor of geochemistry and water quality at Duke University's Nicholas School of the Environment. "The treatment removes a substantial portion of the radioactivity, but it does not remove many of the other salts, including bromide. When the high-bromide effluents are discharged to the stream, it increases the concentrations of bromide above the original background levels. This is significant because bromide increases the risks for formation of highly toxic disinfection byproducts in drinking water treatment facilities that are located downstream."
"The radioactivity levels we found in sediments near the outflow are above management regulations in the U.S. and would only be accepted at a licensed radioactive disposal facility," said Robert B. Jackson, professor of environmental science at Duke. "The facility is quite effective in removing metals such as barium from the water but concentrates sulfates, chlorides and bromides. In fact this single facility contributes four-fifths of the total downstream chloride flow at this point."
"While water contamination can be mitigated by treatment to a certain degree, our findings indicate that disposal of wastewater from both conventional and unconventional oil and gas operations has degraded the surface water and sediments," said Nathaniel R. Warner, a recent Ph.D. graduate of Duke who is now a postdoctoral researcher at Dartmouth College. "This could be a long-term legacy of radioactivity."
Citation: Nathaniel R. Warner, Cidney A. Christie, Robert B. Jackson, and Avner Vengosh, 'Impacts of Shale Gas Wastewater Disposal on Water Quality in Western Pennsylvania', Environmental Science & Technology October 2, 2013 DOI: 10.1021/es402165b