hydraulic fracturing water cycle

A Rutgers University-led study has found that the wastewater from oil and gas operations including fracking for shale gas has been responsible for altering of microbes in West Virginia waters.

Scientists were able to demonstrate that wastewater releases, including briny water that contained petroleum and other pollutants, altered not only the numbers of microbes in West Virginia waters, they also impact the diversity, and functions of microbes. The shifts in the microbial community indicated changes in their respiration and nutrient cycling, along with signs of stress, note scientists in their study published in Science of the Total Environment.

Underground reservoirs of oil and natural gas contain water that is naturally occurring or injected to boost production. During fracking, a fracturing fluid and a solid material are injected into an underground reservoir under very high pressure, creating fractures to increase the porosity and permeability of rocks. Liquid pumped to the surface is usually a mixture of the injected fluids with briny water from the reservoir. It can contain dissolved salt, petroleum and other organic compounds, suspended solids, trace elements, bacteria, naturally occurring radioactive materials and anything injected into wells. Such water is recycled, treated and discharged; spread on roads, evaporated or infiltrated; or injected into deep wells.

The oil and gas industry has been increasingly using fracking lately and its wastewater has increased dramatically in recent years. Scientists say that this increase could overwhelm local infrastructure and strain many parts of the post-fracking water cycle, including the storage, treatment, reuse, transportation or disposal of the wastewater.

Scientists collected water and sediment from tributaries of Wolf Creek in West Virginia in June 2014, including an unnamed tributary that runs through an underground injection control facility. The facility includes a disposal well, which injects wastewater to 2,600 feet below the surface, brine storage tanks, an access road and two lined ponds (now-closed) that were used to temporarily store wastewater to allow particles to settle before injection.

Water samples were shipped to Rutgers, where they were analyzed. Sediment samples were analyzed at the Waksman Genomics Core Facility at Rutgers. The study generated a rich dataset from metagenomic sequencing, which pinpoints the genes in entire microbial communities, scientists note.

Findings indicate that there has been shift in microbial community and antibiotic resistance. The use of biocides in some fracturing fluids raised the question of whether this type of wastewater could serve as an environment that is favorable for increasing antimicrobial resistance. Antimicrobial resistance detected in these sediments did not rise to the levels found in municipal wastewater – an important environmental source of antimicrobial resistance along with agricultural sites.

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