Collaborative Research: Enhanced Biogeochemical Flushing of Uranium in Groundwater

合作研究：地下水中铀的强化生物地球化学冲洗

• 批准号: 2229869
• 负责人: Charles Paradis
• 金额: $ 35万
• 依托单位: University of Wisconsin-Milwaukee
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2229869&HistoricalAwards=false
• 关键词: Collaborative; Research; Enhanced; Biogeochemical; Flushing

Approximately 115 million people in the United States use groundwater as source of drinking water. Many groundwater aquifers are contaminated with uranium from both natural and anthropogenic sources. Prior to its usage as source of drinking water, uranium contaminated groundwater needs to be treated to achieve a target concentration below the EPA MCL (Maximum Concentration Limit) of 30 micrograms per liter (µg/L). In-situ immobilization is currently the leading remediation technology for uranium-contaminated aquifers. This approach relies on the manipulation of the redox biogeochemistry of uranium to reduce and convert mobile uranyl [U(VI)] ions to the mineral uraninite (UO2) which is generally considered immobile in uranium-contaminated aquifers. However, uraninite is highly susceptible to re-oxidation and re-mobilization by oxidants such as oxygen, thus limiting the efficacy of in-situ immobilization as a remediation technology. The goal of this project is to investigate the enhanced biogeochemical mobilization and flushing of uranium from contaminated aquifers as an alternative remediation technology. To advance this goal, the Principal Investigators (PIs) propose to carry out an integrated research program with field, laboratory, and modeling studies to characterize and unravel the biogeochemical reactions and microbial processes that control uranium mobilization in contaminated aquifers. The successful completion of this research will benefit society through the generation of new fundamental knowledge, data and validated models to advance the design and implementation of more efficient and cost-effective remediation technologies for uranium contaminated aquifers. Additional benefits to society will be accomplished through education and outreach including the mentoring of one graduate student and one post-doctoral scholar at the University of Wisconsin-Milwaukee and one graduate student at the University of Wisconsin-Madison.The remediation of uranium-contaminated aquifers has been largely focused on immobilizing uranium by stimulating the abiotic and biotic processes and reactions that control the reduction and conversion of soluble and mobile uranyl [U(VI)] ions to stable and immobile uraninite minerals. However, in situ immobilization has limited effectiveness and the estimated times to naturally flush uranium to below the EPA MCL often exceed hundreds of years. The overarching goal of this research is to understand how to better tune and manipulate the biogeochemical processes and reactions that control the mobility of uranium in contaminated aquifers with the aim of enhancing uranium mobilization and flushing from these aquifers through the injection of oxygen and bicarbonate enriched surface water. The specific objectives of the research are to: 1) Characterize and unravel the biogeochemical mechanisms of uranium mobilization using geochemical modeling and available thermodynamic and kinetic reaction data, 2) Conduct laboratory experiments to investigate the effect of microbial activity on the mobility of uranium under oxygen- and carbonate-rich conditions, and 3) Determine flow and reactive transport parameters to support the implementation and validation of a uranium transport/mobilization model using finite difference numerical modeling and available uranium mobilization data from single-well tracer experiments. The successful completion of this project has the potential for transformative impact through the generation of fundamental knowledge and modeling tools to advance the design and implementation of in-situ enhanced mobilization and flushing as an alternative remediation technology for uranium contaminated aquifers. To implement the educational and outreach goals of this project, the Principal Investigators (PIs) propose to integrate the findings from this research into an existing course at the University of Wisconsin-Madison. In addition, the PIs plan to leverage existing programs at their respective institutions to design and build an exhibition panel on metal contamination in groundwater and aquifers in Wisconsin that will be displayed at the Northern Great Lakes Visitor Center for viewing by Summer 2024.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.

在美国，大约有1.15亿人使用地下水作为饮用水源。许多地下水含水层受到自然和人为来源的铀污染。在用作饮用水源之前，铀污染的地下水需要进行处理，以达到低于EPA MCL（最大浓度限值）30微克/升（µg/L）的目标浓度。原位固定是目前铀污染含水层的主要修复技术。这种方法依赖于对铀的氧化还原地球化学的操纵，以将移动的铀酰[U（VI）]离子还原并转化为矿物晶质铀矿（UO 2），晶质铀矿通常被认为在铀污染的含水层中是不移动的。然而，晶质铀矿极易被氧化剂如氧气再氧化和再活化，从而限制了原位固定作为修复技术的功效。该项目的目标是研究作为一种替代补救技术，从受污染的含水层中加强铀的生物地球化学动员和冲洗。为了推进这一目标，主要研究人员（PI）建议开展一项综合研究计划，包括现场、实验室和建模研究，以表征和揭示控制受污染含水层中铀流动的生物地球化学反应和微生物过程。这项研究的成功完成将通过产生新的基础知识、数据和经验证的模型来促进设计和实施更有效和更具成本效益的铀污染含水层修复技术，从而造福社会。还将通过教育和外联活动，包括指导威斯康星大学密尔沃基分校的一名研究生和一名博士后学者以及威斯康星大学麦迪逊分校的一名研究生，为社会带来更多的惠益。受污染的含水层主要集中在通过刺激控制可溶性铀的还原和转化的非生物和生物过程和反应来固定铀。和移动的铀酰[U（VI）]离子转化为稳定且不移动的晶质铀矿矿物。然而，原位固定的效果有限，估计天然冲洗铀至EPA MCL以下的时间通常超过数百年。这项研究的首要目标是了解如何更好地调整和操纵控制铀在受污染含水层中流动性的地球化学过程和反应，目的是通过注入富含氧气和碳酸氢盐的地表水，加强铀的流动和从这些含水层中冲洗出来。研究的具体目标是：1）利用地球化学建模和现有的热力学和动力学反应数据，描述和揭示铀活动的地球化学机制，2）进行实验室实验，研究微生物活动对富氧和富碳酸盐条件下铀流动性的影响，利用有限差分数值模拟和单井示踪剂实验获得的铀活化数据，确定流动和反应性迁移参数，以支持铀迁移/活化模型的实施和验证。该项目的成功完成有可能通过产生基础知识和建模工具来推动设计和实施现场增强动员和冲洗作为铀污染含水层的替代补救技术，从而产生变革性影响。为了实现本项目的教育和推广目标，主要研究者（PI）建议将本研究的结果整合到威斯康星大学麦迪逊分校的现有课程中。此外，本发明还提供了一种方法，计划利用各自机构的现有项目，设计和建造一个关于威斯康星州地下水和含水层中金属污染的展览板，该展览板将于2024年夏季在北方五大湖游客中心展出。该奖项反映了美国国家科学基金会的法定使命，并被认为值得通过利用基金会的知识价值和更广泛的影响进行评估来支持审查标准。