Study ties fracking to radioactive wastewater
Two Dartmouth studies recently established a link between fracking and the production of radioactive wastewater. Lead researcher and senior research scientist Josh Landis and his team found that the prevalent radioactive material in wastewater after hydraulic fracking comes from the interaction between slick water and black shale.
“Prior to our work, everyone was assuming that the radium was from pre-existing [briny water] found underground,” Landis said.
However, Landis added the study points to the controversial oil and gas extraction method as the cause of this radioactive waste.
“We are able to argue pretty vigorously that the fracking itself is producing the fluid,” he said. “[This] shows that the frackers are responsible for its creation, and if you want to minimize its production, you have to do that through their process.”
According to Sharma, radioactive wastewater cannot currently be treated. It is either mixed with fresh water and used to frack again, or it is sent away to be buried into the ground. For example, radioactive wastewater from fracking locations in Pennsylvania may be sent to Ohio, Sharma said.
Over the past 10 years, the prevalence of fracking has greatly increased and grown more controversial due to its environmental impact.
“Fracking is an important invention that has allowed us to become more or less sufficient [in the U.S.] in terms of energy,” Mukul said.
During the process of fracking, slick water — water with added chemicals — is pumped deep into the rock to release the gas inside. The fractured shale absorbs about three-quarters of this water, and the rest returns to the surface, full of radium. The first study — focused on the rapid desorption of radium from black shale — found that radium comes from both organic and mineral surfaces as the wastewater moves toward the surface. The second study contextualized the first study’s findings with the available data from research in fracking on radium isotopes.
Landis said he got the idea to look at radium after seeing the work that his future co-authors, earth science professor Mukul Sharma and earth sciences professor Devon Renock, were doing with barium. Sharma and Renock had been researching the chemical reactions during fracking that produce the toxic metal barium in wastewater. Since radium and barium belong to the same periodic family, Landis said he was able to adopt aspects of their methods to study the radium found in the wastewater.
Landis added that he and Sharma believed that radium could offer insight that barium could not.
The team of researchers carried out experiments on rock samples taken from the Marcellus shale in Pennsylvania and New York. They found that the radium came from the rock, not pre-existing brine as previously thought, and the experiments focused on understanding the conditions needed for radium to be released from the rock itself.
The radium is originally found within a few nanometers of the surface in two distinct locations: a clay mineral surface that transfers one type of radium and an organic surface that transfers another type of radium. Landis and his team found that when high salinity water passes by the mineral or organic surface, radium is ejected from its surface and added to the solution, turning the saline water radioactive.
An important question researchers are still examining is the source of this saline water, Sharma said. The original slick water that is ejected into the rock contains a mixture of chemicals including biocides and hydrochloric acid, which help to increase the flow of fluids. Though this water contains little to no salt, the wastewater that comes back up is 10 times more saline than ocean water. The salinity of wastewater from fracking is important because the slick water alone does not extract radium, according to Sharma. Rather, the high saline composition of the wastewater is responsible.
However, the oil and gas produced poses environmental concerns. Divest Dartmouth, a sustainability group on campus, is pushing the College to divest from the fossil fuel industry.
“The fossil fuel industry is pretty exploitative of communities that live in the area they are extracting from,” Divest Dartmouth member Camille Pauley ’21 said. “Even if there are the economic gains from jobs, they do come at strong environmental costs. This research shows the seriousness of some of those costs, and I don’t think we really know what the consequences are going to be.”
Sharma added that he thought about researching the “serious problems” surrounding fracking as the study progressed.
“The key here is to try to optimize its production so we don’t foul up the places all around,” he said. “These communities should not get impacted substantially.
Correction appended (Sept. 28, 2018):
The original version of this article incorrectly named Joshua Landis as a professor of earth sciences instead of a senior research scientist at the College. This error has been corrected.