According to a report in Shale Gas Bulletin Ireland Scientists from Duke University have found that wastewater from oil and gas drilling (conventional and unconventional) contains high levels of ammonium and iodide, potentially hazardous substances that have not been associated with the petroleum industry to date.
The findings were published in the peer-reviewed journal Environmental Science and Technology and are discussed in this Scientific American article.
The rport goes on to say when dissolved in water or mixed with other pollutants, ammonium and iodide can encourage the formation of toxic substances.
Because it was not known until now that wastewater from oil and gas drilling contained these contaminants, their presence is not being monitored or controlled in the wastewater that is often released into rivers and streams following treatment. The scientists found that “current brine treatment practice in Pennsylvania is not sufficient to remove these contaminants.”
Ammonium can convert to ammonia, highly toxic to aquatic life.
The Duke scientists found ammonium levels of up to 100 mg/L in samples from wastewater discharge sites, 50 times higher than the threshold set by the US EPA for protecting freshwater organisms.
The Bulletin further repoirts that Iodide can promote the formation of highly toxic byproducts that pose a threat to drinking water.
If a municipal treatment plant located downstream from a wastewater discharge point treats intake water using chlorine, this could combine with the iodide in the wastewater to form toxic disinfection by-products.
The report concludes “These and the other highly toxic substances that fracking wastewater is known to contain are of particular concern to residents of North Dakota, where three million gallons of fracking wastewater spilled from a leaking pipe last month.
In an interview, Anver Vengosh, one of the authors of the Duke study discussed above, found that wastewater from North Dakota’s oil and gas operations is “ten times saltier than the ocean, that endangers aquatic life and trees, and it has ammonium and radioactive elements.”