Hydraulic fracturing flowback and produced water (HF-FPW), which contains polyaromatic hydrocarbons (PAHs) and numerous other potential contaminants, is a complex wastewater produced during the recovery of tight hydrocarbon resources. Previous studies on HF-FPW have demonstrated various toxicological responses of aquatic organisms as consequences of combined exposure to high salinity, dissolved organic compounds and particle/suspended solids-bound pollutants. Noteworthy is the lack of studies illustrating the potentially toxic effects of the FPW suspended solids (FPW-SS). In this study, we investigated the acute and sublethal toxicity of suspended solids filtered from six authentic FPW sample collected from two fracturing wells, using a sediment contact assay based on early-life stages of zebrafish (). PAHs profiles and acute toxicity tests provided initial information on the toxic potency of the six samples. Upon exposure to sediment mixture at two selected doses (1.6 and 3.1 mg/mL), results showed adverse effects in larval zebrafish, as revealed by increased Ethoxyresorufin-O-deethylase (EROD) activity. Transcriptional alterations were also observed in xenobiotic biotransformation (, , , , , , , , ), antioxidant response (, , , ) and hormone receptor signaling (, , , ) genes. The results demonstrated that even separated from the complex aqueous FPW mixture, FPW-SS can induce toxicological responses in aquatic organisms' early life stages. Since FPW-SS could sediment to the bottom of natural wetland acting as a continuous source of contaminants, the current findings imply the likelihood of long-term environmental risks of polluted sediments on aquatic ecosystems due to FPW spills.

中文翻译：

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斑马鱼（Danio rerio）生命早期阶段水力压裂回流和采出水与悬浮固体相关的毒性

水力压裂回流和采出水（HF-FPW）含有多环芳烃（PAH）和许多其他潜在污染物，是致密碳氢化合物资源回收过程中产生的复杂废水。先前对 HF-FPW 的研究表明，水生生物因同时暴露于高盐度、溶解有机化合物和颗粒/悬浮固体结合污染物而产生各种毒理学反应。值得注意的是，缺乏说明 FPW 悬浮固体 (FPW-SS) 潜在毒性作用的研究。在这项研究中，我们使用基于斑马鱼生命早期阶段的沉积物接触测定法，研究了从两个压裂井收集的六个真实 FPW 样品中过滤出的悬浮固体的急性和亚致死毒性。 PAH 概况和急性毒性测试提供了有关六个样品毒性效力的初步信息。暴露于两种选定剂量（1.6 和 3.1 mg/mL）的沉积物混合物后，结果显示对斑马鱼幼虫产生不利影响，如乙氧基试卤灵-O-脱乙基酶 (EROD) 活性增加。在外源生物转化 (, , , , , , , , )、抗氧化反应 (, , , ) 和激素受体信号传导 (, , , ) 基因中也观察到转录改变。结果表明，即使从复杂的 FPW 水溶液混合物中分离出来，FPW-SS 也能在水生生物的早期生命阶段引起毒理学反应。由于 FPW-SS 可以沉积到自然湿地底部，成为连续的污染物源，目前的研究结果表明，由于 FPW 泄漏，沉积物污染可能对水生生态系统造成长期环境风险。