U.S. Geological Survey, Reston, Virginia, USA
U.S. Geological Survey, Reston, Virginia, USA.
Appl Environ Microbiol. 2018 Apr 2;84(8). doi: 10.1128/AEM.02729-17. Print 2018 Apr 15.
The development of unconventional oil and gas (UOG) resources results in the production of large volumes of wastewater containing a complex mixture of hydraulic fracturing chemical additives and components from the formation. The release of these wastewaters into the environment poses potential risks that are poorly understood. Microbial communities in stream sediments form the base of the food chain and may serve as sentinels for changes in stream health. Iron-reducing organisms have been shown to play a role in the biodegradation of a wide range of organic compounds, and so to evaluate their response to UOG wastewater, we enriched anaerobic microbial communities from sediments collected upstream (background) and downstream (impacted) of an UOG wastewater injection disposal facility in the presence of hydraulic fracturing fluid (HFF) additives: guar gum, ethylene glycol, and two biocides, 2,2-dibromo-3-nitrilopropionamide (DBNPA) and bronopol (CHBrNO). Iron reduction was significantly inhibited early in the incubations with the addition of biocides, whereas amendment with guar gum and ethylene glycol stimulated iron reduction relative to levels in the unamended controls. Changes in the microbial community structure were observed across all treatments, indicating the potential for even small amounts of UOG wastewater components to influence natural microbial processes. The microbial community structure differed between enrichments with background and impacted sediments, suggesting that impacted sediments may have been preconditioned by exposure to wastewater. These experiments demonstrated the potential for biocides to significantly decrease iron reduction rates immediately following a spill and demonstrated how microbial communities previously exposed to UOG wastewater may be more resilient to additional spills. Organic components of UOG wastewater can alter microbial communities and biogeochemical processes, which could alter the rates of essential natural attenuation processes. These findings provide new insights into microbial responses following a release of UOG wastewaters and are critical for identifying strategies for the remediation and natural attenuation of impacted environments.
非常规油气（UOG）资源的开发会产生大量含有水力压裂化学添加剂和地层成分的复杂混合物的废水。这些废水排放到环境中会带来潜在风险，而这些风险目前还了解甚少。溪流沉积物中的微生物群落是食物链的基础，它们可能是溪流健康变化的哨兵。已经表明，铁还原生物在广泛的有机化合物的生物降解中发挥作用，因此为了评估它们对 UOG 废水的反应，我们在存在水力压裂液（HFF）添加剂：瓜尔胶、乙二醇和两种杀菌剂 2,2-二溴-3-亚硝丙酰胺（DBNPA）和溴硝醇的情况下，从 UOG 废水注入处置设施的上游（背景）和下游（受影响）沉积物中富集了厌氧微生物群落。在添加杀菌剂的情况下，铁还原在孵育早期受到显著抑制，而添加瓜尔胶和乙二醇相对于未添加对照物刺激了铁还原。在所有处理中都观察到微生物群落结构的变化，这表明即使是少量的 UOG 废水成分也可能影响自然微生物过程。背景和受影响沉积物的富集物中的微生物群落结构不同，这表明受影响的沉积物可能已经通过暴露于废水而得到了预处理。这些实验表明，杀菌剂在泄漏后立即显著降低铁还原率的潜力，并表明先前暴露于 UOG 废水中的微生物群落可能对额外的泄漏更具弹性。UOG 废水的有机成分可以改变微生物群落和生物地球化学过程，从而改变必要的自然衰减过程的速率。这些发现为 UOG 废水释放后微生物的反应提供了新的见解，对于确定受影响环境的修复和自然衰减策略至关重要。
