EAGER: Assessment of Coupled Hydraulic Fracturing Fluid Mass Transfer and Biodegradation in Shallow Aquifer Systems

水力压裂液(HFFS)是用于水力开采石油(水力压裂)的流体混合物。尽管在运行期间实施了旨在遏制HFFS的措施，但与运输、液体混合、注入、储存和油井套管故障相关的意外泄漏已导致HFFS污染饮用水供应。这种排放可能会影响土壤、地表水和/或含水层，可能需要采取纠正行动来限制污染的程度。此外，由于HFF是复杂的混合物，有必要了解混合物中所有组分的环境命运，包括有机添加剂、表面活性剂、杀生剂和盐。拟议的研究旨在更全面地了解环境中影响HFF的生物和化学反应。这些结果将有助于为监管决策提供信息，并为HFF向环境排放的可持续管理和补救战略提供技术基础。该项目还将通过将本科生纳入实验室研究，将教育举措纳入课堂教学和学术出版的传统框架之外。这项研究还将有助于通过招聘女性和未被充分代表的少数民族理工科本科生和研究生来加强国家S的人才库。最后，通过与环境咨询公司合作与从业者分享成果，以及对可能因水力压裂而负担过重的社区，结果将产生广泛影响。以前的研究表明，水力压裂液(HFF)中的有机化合物(如石油碳氢化合物、胶凝剂和杀生剂)对从深层页岩中获得的现场样品和实验室规模的反应堆中的自然衰减具有潜在的敏感性。然而，环境中特定的HFF组分的物理化学传质和生物介导的转化反应在很大程度上是未知的，这可能威胁到受HFF排放影响的饮用水供应的安全。这项研究的目的是在代表浅层含水层的条件下研究高频辐射，重点是高频辐射有机成分(例如，萘和苯)的生物转化。该研究计划围绕三项任务展开，旨在：(1)开发一种具有良好特性的合成HFF混合物并表征田间回流；(2)测量HFF成分的吸附和解吸作为土壤特性和盐度的函数；以及(3)量化HFF的生物降解、微生物群落反应和分解代谢基因表达作为HFF暴露浓度的函数。这项研究的新方面包括将微生物群落分析与目标分子技术相结合以评估结构和功能，以及使用先进的质谱学技术来表征流出物和识别降解产物。这项工作的结果将提高对以下问题的理解：(A)影响复杂、高有机碳废流中有机化合物反应和副产品形成的自然衰减过程(物理-化学和生物)，(B)本地地下微生物群落影响HFF质量传递(最终影响HFF成分寿命)的潜力，以及(C)修复和管理受HFF影响的场地的可持续、低强度方法(即自然衰减)。具体地说，从这项工作中得出的实验速率参数将帮助环境专业人员评估一系列环境相关条件下的自然衰减能力。此外，这些结果将为设计未来研究HFF在多维系统中的命运和运输提供初步数据和技术基础，并有助于开发改进浅层含水层系统中HFF管理的数学模型。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

Hydraulic fracturing fluids (HFFs) are fluid mixtures used for hydraulic extraction of petroleum (fracking). Despite the implementation of measures designed to contain HFFs during operation, accidental releases associated with transportation, fluid mixing, injection, storage, and well casing failures have led to contamination of drinking water supplies by HFFs. Such releases can impact soil, surface waters, and/or aquifers, potentially requiring corrective action to limit the extent of contamination. Further, as HFFs are complex mixtures, it is necessary to understand the environmental fate of all components of the mixture, which includes organic additives, surfactants, biocides, and salts. The proposed research aims to obtain a more complete understanding of the biological and chemical reactions impacting HFF in the environment. These results will help to inform regulatory decisions, and provide the technical basis for sustainable management and remediation strategies for HFF releases to the environment. The project will also incorporate education initiatives beyond the traditional framework of classroom instruction and scholarly publication, through the inclusion of undergraduate students in laboratory research. This research will also help to strengthen the Nation?s pool of talent through the recruitment of female and underrepresented minority science and engineering undergraduate and graduate students. Finally, the results will be broadly impactful through the sharing with practitioners through collaboration with environmental consulting firms, as well as to communities that may be disproportionately burdened by hydraulic fracturing. Previous studies have shown the potential susceptibility of organic compounds (e.g., petroleum hydrocarbons, gelling agents and biocides) in hydraulic fracturing fluid (HFF) to natural attenuation in field samples obtained from deep shale and in laboratory-scale reactors. However, the physical-chemical mass transfer and biologically-mediated transformation reactions of specific HFF components in the environment is largely unknown, potentially threatening the safety of drink water supplies impacted by HFF releases. The goal of the research is to investigate HFF under conditions representative of shallow aquifers, with an emphasis on biotic transformations of HFF organic constituents (e.g., naphthalene and benzene). The research program is structured around three tasks that are designed to: (1) develop a well-characterized synthetic HFF mixture and characterize field-derived flowback, (2) measure the sorption and desorption of HFF constituents as a function of soil properties and salinity, and (3) quantify HFF biodegradation, microbial community response and catabolic gene expression as a function of HFF exposure concentration. Novel aspects of this research include the coupling of microbial community analysis with targeted molecular techniques to assess both structure and function, and the use of advanced mass spectrometry techniques to characterize effluent streams and identify degradation products. Results of this work will improve understanding of: (a) natural attenuation processes (physical-chemical and biological) impacting organic compound reactivity and byproduct formation in a complex, high organic carbon waste stream, (b) the potential of native subsurface microbial communities to influence HFF mass transfer (and ultimately, HFF constituent longevity) and, (c) a sustainable, low-intensity approach (i.e., natural attenuation) for remediation and management of HFF-impacted sites. Specifically, the experimental rate parameters derived from this work will assist environmental professionals assess natural attenuation capacity for a range of environmentally relevant conditions. Further, these results will provide preliminary data and the technical basis for the design of future studies examining the fate and transport of HFF in multi-dimensional systems, and aid in the development mathematical models for improved management of HFF in shallow aquifer systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.