Whether trickling from cracked shale deep underground or gushing through an old-school well, wastewater from oil and gas production may carry two additional dangerous chemicals besides those previously known.
Harmful levels of ammonium and iodide have now been found in wastewater from conventional oil and gas production plus the more controversial practice of hydraulic fracturing, known as fracking. The chemicals, pulled up from the Earth, arrive at the surface at concentrations high enough to harm aquatic life and form cancer-causing compounds when mixed with the chlorine in tap water, researchers report January 14 in Environmental Science & Technology.
Wastewater from oil and gas is known to contain cocktails of dangerous components, including arsenic, radioactive material and naphthalene. But ammonium and iodide have not been reported in fracking wastewater before. And little research has examined the toxicity of these two chemicals in wastewater from conventional oil and gas wells.
Researchers led by environmental geochemist Avner Vengosh of Duke University tested water samples from conventional wells, fracking sites, oil and gas wastewater treatment facilities and a wastewater spill site. Samples came from Pennsylvania, West Virginia, New York and Arkansas.
The researchers found high levels of both ammonium and iodide in many samples. Even treated wastewater had levels of ammonium up to 50 times higher than the maximum levels found to be safe by the U.S. Environmental Protection Agency.
Editor’s note: This story was updated January 15, 2015, to include New York and Arkansas in the list of sampling locations.