CSU researchers: Fracking spills on ag land need more scrutiny
FORT COLLINS — More scientific research is needed about how spilled chemicals interact with each other and the underground chemical environment, according to a Colorado State University research team that studied fracking-related spills on and near agricultural land.
The need for more information applies not just to oil and gas extraction but to many other industrial processes as well, the researchers said in a report released Wednesday. Such follow-up studies could lead to a better understanding of water contamination above and below ground, as well as how crops could absorb pollutants. The ultimate goal, they said, could be to help improve how spills are assessed as potential risks to human health.
Hydraulic fracturing, commonly known as “fracking,” is a method for extracting oil and gas from otherwise impenetrable shale and rock formations and is widely used in the Wattenberg and Denver-Julesburg fields in Northern Colorado. It involves not only underground injections composed mostly of water, but also a mixture of chemical additives ranging from toxic biocides and surfactants to corrosion inhibitors and slicking agents, many of which also are used by other industries.
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The CSU researchers — Thomas Borch, a professor in the Department of Soil and Crop Sciences in the College of Agricultural Sciences; Jens Blotevogel, a research assistant professor in civil and environmental engineering; and graduate student Molly McLaughlin — wanted to understand what happened to those chemicals when they are spilled accidentally during either transportation or production in oil and gas operations, especially on or near agricultural land. The two professors have worked together for about nine years.
The team studied 838 fracking-fluid spills that were reported to the Colorado Oil and Gas Conservation Commission in 2014. They limited their study to spills larger than five barrels of fluid when they happened within a well pad and larger than one barrel when outside a well pad.
The team used reactors to simulate chemical reactions and biodegradation of fracking additives spilled onto soil on ag lands, and plan to test their conclusions at actual spill sites.
They tested three organic chemicals: polyethylene glycol (PEG), a commonly used surfactant; glutaraldehyde, a biocide that prevents pipe corrosion from microbial activity; and polyacrylamide, a slicking agent that allows fracking fluid to better penetrate shale. They looked at how these chemicals interact both with each other and with naturally occurring salts underground.
They found that the PEG by itself completely biodegrades within about 70 days, but that when it was combined with glutaraldehyde, it stayed in the soil much longer. That biodegradation was fully inhibited by salt concentrations typical for oil and gas extraction activities.
“Our motivation for doing this is because the chemicals often come up as mixtures,” Borch said. “While you may see biodegradation of a surfactant under normal circumstances, if you spill that together with a biocide that kills bacteria, maybe you don’t break that surfactant down as quickly. And that’s exactly what we see. If chemicals don’t degrade as quickly, it gives them more time to be transported to groundwater or sensitive surface water.”
They found that glutaraldehyde degraded within about two months, while polyacrylamide stuck around in the soil for six months. When bonded with the glutaraldehyde, however, it effectively lowered the biocide’s toxicity.
“We cannot say our findings are valid for all the different chemicals used worldwide in hydraulic fracturing,” Blotevogel said. “There are probably 1,000 different chemicals used globally, and they all behave very differently with respect to how they are broken down.”
The team’s results are online in the American Chemical Society’s journal, Environmental Science and Technology. The study was supported primarily by CSU’s School of Global and Environmental Sustainability, a grant from the CSU Water Center and by the Borch-Hoppess Fund for Environmental Contaminant Research.
