Spills of Hydraulic Fracturing Chemicals on Agricultural Topsoil: Biodegradation, Sorption, and Co-contaminant Interactions

Abstract

Hydraulic fracturing frequently occurs on agricultural land. Yet the extent of sorption, transformation, and interactions among the numerous organic frac fluid and oil and gas wastewater constituents upon environmental release is hardly known. Thus, this study aims to advance our current understanding of processes that control the environmental fate and toxicity of commonly used hydraulic fracturing chemicals. Poly(ethylene glycol) surfactants were completely biodegraded in agricultural topsoil within 42-71 days, but their transformation was impeded in the presence of the biocide glutaraldehyde and was completely inhibited by salt at concentrations typical for oil and gas wastewater. At the same time, aqueous glutaraldehyde concentrations decreased due to sorption to soil and were completely biodegraded within 33-57 days. While no aqueous removal of polyacrylamide friction reducer was observed over a period of 6 months, it cross-linked with glutaraldehyde, further lowering the biocide's aqueous concentration. These findings highlight the necessity to consider co-contaminant effects when we evaluate the risk of frac fluid additives and oil and gas wastewater constituents in agricultural soils in order to fully understand their human health impacts, likelihood for crop uptake, and potential for groundwater contamination.

A review on the removal of conditioning chemicals from cooling tower water in constructed wetlands

“…Many biocides can be biodegraded, including the most commonly used biocide glutaraldehyde (Campa et al, 2018;Kahrilas, Blotevogel, Corrin, & Borch, 2016;Kahrilas, Blotevogel, Stewart, & Borch, 2015;Laopaiboon, Phukoetphim, Vichitphan, & Laopaiboon, 2008;McLaughlin, Borch, & Blotevogel, 2016;Rogers, Ferrer, Tummings, Bielefeldt, & Ryan, 2017). Although biodegradation of a biocide sounds counterintuitive, biocides are biodegraded if their concentration is below the effect concentration or if the biocide does not target all microorganisms present.…”

“…Although biodegradation of a biocide sounds counterintuitive, biocides are biodegraded if their concentration is below the effect concentration or if the biocide does not target all microorganisms present. In addition, adsorption of glutaraldehyde to the sediment resulted in a decreased effective concentration and increased biodegradation (McLaughlin et al, 2016). Additionally, the formation of biofilms, as in surface flow CWs, has also shown to mitigate the negative effects of biocides by their protective functioning.…”

Groundwater Quality and Hydraulic Fracturing: Current Understanding and Science Needs

“…Biocides suppress the growth of sulfate-reducing bacteria downhole. They are toxic by design and pose perhaps the greatest risk to groundwater of all the chemical additives in a frack (Kahrilas et al 2015;McLaughlin et al 2016).…”

A Sustainable Rural Food–Energy–Water Nexus Framework for the Northern Great Plains

“…2015; McLaughlin et al, 2016), and reduced fresh water supplies (Horner et al, 2016). As climate change progresses, water supplies will become less predictable and may, in some areas, be lost.…”