Surface spills of flowback and produced water (FPW), fluids which return to the surface following hydraulic fracturing in shale oil and gas reservoirs, may cause detrimental effects to aquatic environments. In this study, we investigated responses of microbiota in surface waters exposed to FPW derived from fracturing of the Duvernay Formation, Canada. Changes in microbial community structure and important bioindicators were tracked at various FPW concentrations over seven days under aerobic conditions using 16S rRNA gene sequencing. Three distinct shift pathways for microbial communities were identified at the three FPW concentration ranges tested: (1) from 0% to 0.5% FPW, indigenous surface water genera Flavobacterium, Methylotenera, and Caulobacter were predominant, (2) from 2.5% to 5% FPW, microbial communities shifted to potential organics degraders such as Pseudomonas, Rheinheimera, and Brevundimonas, and (3) from 25% to 50% FPW, microbial shifts were not significant. Using these 16S data, these enriched genera were also identified by Random Forests (2% classified error in 1000 runs) as essential bioindicators to predict spill magnitude, information that was used to develop a machine learning-based model. Our study indicates that a few key microorganisms are likely to attenuate organics derived from FPW spills in surface waters, and that significant responses of the surface microbiota to FPW contaminants start at modest FPW to fresh water ratios.

Responses of surface water microbial communities exposed to spills of flowback and produced water

2019 Fall National Meeting

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