National Energy Technology Laboratory , Pittsburgh, Pennsylvania 15236, United States.
Environ Sci Technol. 2013 Nov 19;47(22):13141-50. doi: 10.1021/es402928b. Epub 2013 Oct 31.
Microbial communities associated with produced water from hydraulic fracturing are not well understood, and their deleterious activity can lead to significant increases in production costs and adverse environmental impacts. In this study, we compared the microbial ecology in prefracturing fluids (fracturing source water and fracturing fluid) and produced water at multiple time points from a natural gas well in southwestern Pennsylvania using 16S rRNA gene-based clone libraries, pyrosequencing, and quantitative PCR. The majority of the bacterial community in prefracturing fluids constituted aerobic species affiliated with the class Alphaproteobacteria. However, their relative abundance decreased in produced water with an increase in halotolerant, anaerobic/facultative anaerobic species affiliated with the classes Clostridia, Bacilli, Gammaproteobacteria, Epsilonproteobacteria, Bacteroidia, and Fusobacteria. Produced water collected at the last time point (day 187) consisted almost entirely of sequences similar to Clostridia and showed a decrease in bacterial abundance by 3 orders of magnitude compared to the prefracturing fluids and produced water samplesfrom earlier time points. Geochemical analysis showed that produced water contained higher concentrations of salts and total radioactivity compared to prefracturing fluids. This study provides evidence of long-term subsurface selection of the microbial community introduced through hydraulic fracturing, which may include significant implications for disinfection as well as reuse of produced water in future fracturing operations.
与水力压裂产生的采出水相关的微生物群落尚未得到很好的理解，其有害活动可能导致生产成本显著增加和环境负面影响。在这项研究中，我们使用 16S rRNA 基因克隆文库、焦磷酸测序和定量 PCR 比较了宾夕法尼亚州西南部一口天然气井在多个时间点的预压裂液（压裂源水和压裂液）和采出水中的微生物生态学。预压裂液中的大多数细菌群落由与 α 变形菌纲相关的需氧种组成。然而，随着耐盐、厌氧/兼性厌氧种的相对丰度增加，它们在采出水中的相对丰度降低，这些种与梭菌纲、芽孢杆菌纲、γ 变形菌纲、ε 变形菌纲、拟杆菌纲和梭杆菌纲有关。在最后一个时间点（第 187 天）采集的采出水中几乎完全由类似于梭菌的序列组成，与预压裂液和早期时间点的采出水样本相比，细菌丰度下降了 3 个数量级。地球化学分析表明，与预压裂液相比，采出水中含有更高浓度的盐和总放射性。本研究提供了通过水力压裂引入的微生物群落的长期地下选择的证据，这可能对消毒以及未来压裂作业中采出水的再利用产生重大影响。
