Slick Water and Black Shale in Fracking Produce Radioactive Waste

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Researchers from Dartmouth College suggested that hydraulic fracturing for oil and gas transfers radium to wastewater

The U.S. is a net exporter of gas, owing to fracking and is expected to become a net exporter of oil in the near future. However, the wastewater produced in the process of oil and natural gas manufacturing contains toxins such as barium and radioactive radium. Radium upon decay releases other elements such as radon that collectively generate high radioactivity. Millions of gallons of water during fracking is combined with sand and a mixture of chemicals and is pumped deep underground at high pressure. By breaking apart the shale, the pressurized water forces out natural gas and oil. The sand prevents the fractures from resealing and a large proportion of the slick water returns to the surface as highly toxic waste.

The research team at Dartmouth College combined sequential and serial extraction experiments to leach radium isotopes from shale drill core samples. The team focused on rocks taken from Pennsylvania and New York locations of the Marcellus Shale, which is one of the major rock formations in the U.S. for fracking to extract natural gas. In their first research paper, the team found presence of radium in the Marcellus Shale, which was leached into saline water. The leachable radium within the rock had two distinct sources that include, clay minerals with radium-228 and an organic phase with abundant isotope radium-226.

The second paper combined experimental results and isotope mixing models with direct observations of radium present in wastewaters from the Marcellus Shale to describe the radium transfer mechanics. The two papers together revealed that increasing salinity in water produced during fracking draws radium from the fractured rock. The findings confirmed that the wastewater travels through the fracture network and returns to the fracking drill hole. This water is enriched in salts and is responsible for extracting radium from the shale and for bringing it to the surface. The research was published in the journal Chemical Geology on August 3, 2018.

 

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