A comparative ecotoxicity impact assessment of hydraulic fracturing chemicals used in oil and gas and coal-bed methane wells

Abstract In this study, we examine the ecotoxicity impacts of chemicals used in hydraulic-fracturing (HF) operations for shale-based oil and gas (O&G) and coal-bed methane (CBM) wells in Colorado. The chemical constituents of HF fluids were analyzed for 40 O&G and 10 CBM wells located in Weld and Las Animas counties. Integrating toxicity data, physical properties, and fate and transport parameter predictions with the USEtox human and ecotoxicological impact model, we developed new fresh water ecotoxicity characterization factors for 184 different chemicals that are commonly used in fracking operations. Further, we also estimated and analyzed the overall ecotoxicity impacts associated with the potential release of these chemicals into the environment. We found that CBM HF wells, on an average, resulted in 12.6% greater ecotoxicity impacts from chemical release than O&G wells. Ecological Impacts were highly-sensitive to the fraction of HF fluid that returns to the surface as part of flow back.