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。尽管在作业过程中采取了控制HFFs的措施，但与运输、流体混合、注入、储存和套管失效相关的意外泄漏导致了HFFs污染饮用水供应。这种排放可能影响土壤、地表水和/或含水层，可能需要采取纠正措施来限制污染程度。此外，由于HFFs是复杂的混合物，有必要了解混合物中所有成分的环境命运，包括有机添加剂、表面活性剂、杀菌剂和盐。本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，并为向环境释放氢氟化合物的可持续管理和补救战略提供技术基础。该项目还将纳入超越课堂教学和学术出版的传统框架的教育举措，通过将本科生纳入实验室研究。这项研究也将有助于加强国家？通过招募女性和代表性不足的少数民族科学和工程本科生和研究生，扩大美国的人才库。最后，通过与环境咨询公司的合作，与从业者分享，以及对可能因水力压裂而负担过重的社区，结果将产生广泛的影响。先前的研究表明，在深层页岩和实验室规模的反应器中获得的现场样品中，水力压裂液（HFF）中的有机化合物（如石油碳氢化合物、胶凝剂和杀菌剂）对自然衰减的潜在敏感性。然而，环境中特定HFF成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释放影响的饮用水供应的安全。这项研究的目的是调查具有代表性的浅层含水层条件下的HFF，重点是HFF有机成分（如萘和苯）的生物转化。该研究计划围绕三个任务进行，旨在：(1)开发具有良好表征的合成HFF混合物，并表征现场衍生的返排；(2)测量HFF成分的吸附和解吸与土壤性质和盐度的关系；(3)量化HFF的生物降解、微生物群落响应和分解代谢基因表达与HFF暴露浓度的关系。本研究的新方面包括微生物群落分析与靶向分子技术的耦合，以评估结构和功能，以及使用先进的质谱技术来表征流出流和识别降解产物。这项工作的结果将提高对以下方面的理解：(a)影响复杂的高有机碳废物流中有机化合物反应性和副产物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传质（最终影响HFF成分寿命）的潜力，以及(c)可持续的低强度方法（即自然衰减）用于修复和管理受HFF影响的地点。具体来说，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，并有助于建立数学模型，以改善浅层含水层系统中HFF的管理。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识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.