Department of Biological Sciences, University of Alberta , Edmonton, Alberta T6G 2R3, Canada.
Department of Earth and Atmospheric Sciences, University of Alberta , Edmonton, Alberta T6G 2R3, Canada.
Environ Sci Technol. 2017 Mar 7;51(5):3032-3039. doi: 10.1021/acs.est.6b05179. Epub 2017 Feb 13.
Hydraulic fracturing is an industrial process allowing for the extraction of gas or oil. To fracture the rocks, a proprietary mix of chemicals is injected under high pressure, which later returns to the surface as flowback and produced water (FPW). FPW is a complex chemical mixture consisting of trace metals, organic compounds, and often, high levels of salts. FPW toxicity to the model freshwater crustacean Daphnia magna was characterized utilizing acute (48 h median lethal concentrations; LC) and chronic (21 day) exposures. A decrease in reproduction was observed, with a mean value of 18.5 neonates produced per replicate over a 21 day chronic exposure to 0.04% FPW, which was a significant decrease from the average of 64 neonates produced in the controls. The time to first brood was delayed in the highest FPW (0.04%) treatment. Neonates exhibited an LC of 0.19% of full-strength FPW, making them more sensitive than adults, which displayed an LC value of 0.75%. Quantitative PCR highlighted significant changes in expression of genes encoding xenobiotic metabolism (cyp4) and moulting (cut). This study is the first to characterize chronic FPW toxicity and will help with the development of environmental monitoring and risk assessment of FPW spills.
水力压裂是一种提取天然气或石油的工业过程。为了使岩石破裂，将一种专有的化学混合物在高压下注入，随后作为回流和产出水（FPW）返回地面。FPW 是一种复杂的化学混合物，由痕量金属、有机化合物组成，通常还含有高浓度的盐。利用急性（48 小时半数致死浓度；LC）和慢性（21 天）暴露，对模式淡水甲壳动物大型溞的 FPW 毒性进行了表征。在 21 天慢性暴露于 0.04%FPW 中，观察到繁殖减少，每个重复产生的平均幼体数为 18.5 个，与对照中产生的 64 个幼体的平均值相比显著减少。在最高 FPW（0.04%）处理中，首次产卵的时间延迟。幼体对全强度 FPW 的 LC 为 0.19%，比成虫更敏感，成虫的 LC 值为 0.75%。定量 PCR 突出显示了编码外来生物代谢（cyp4）和蜕皮（cut）的基因表达的显著变化。这项研究首次对慢性 FPW 毒性进行了特征描述，将有助于环境监测和 FPW 泄漏风险评估的发展。
