The chemical makeup of wastewater generated by “hydrofracking” could cause the release of tiny particles in soils that often strongly bind heavy metals and pollutants, exacerbating the environmental risks during accidental spills, Cornell researchers have found.

Previous research has shown that 10 to 40 percent of the water and chemical solution mixture injected at high pressure into deep rock strata surges back to the surface during well development. Scientists at the College of Agriculture and Life Sciences studying the environmental impacts of this “flowback fluid” found that the same properties that make it so effective at extracting natural gas from shale can also displace tiny particles that are naturally bound to soil, causing associated pollutants, such as heavy metals, to leach out.

They described the mechanisms of this release and transport in a paper published online June 6 in the American Chemical Society journal Environmental Science and Technology.

The particles they studied are colloids – larger than the size of a molecule but smaller than what can be seen with the naked eye – which cling to sand and soil due to their electric charge.

via Fracking flowback could indirectly pollute groundwater | Cornell Chronicle.