Electrokinetic Biodegradation of Glyphosate: Feasibility, Mechanism, and Transport Modeling

草甘膦是美国和全球使用最广泛的除草剂。全世界每年大约使用80万吨草甘膦。尽管草甘膦(GLYP)对人类健康的影响仍然是持续争论的主题，但暴露在高浓度GLYP下已被证明1)对生态系统健康产生不利影响，包括对水生生态系统中的几个物种的毒性，2)导致抗草甘膦作物的出现，以及杂草种群对除草剂的抗药性。GLYP还可能通过直接机制(如与土壤中植物生长所必需的金属离子的络合作用)或间接机制(如不利影响菌根和蚯蚓的生长和新陈代谢)对土壤质量和肥力产生不利影响，这可能对植物获得养分和土壤水分渗透产生不利影响。此外，GLYP通过自然衰减在生物降解和矿化有限的土壤中积累。鉴于GLYP的广泛使用，其潜在的生态毒性，以及自然衰减的局限性，迫切需要更有效、更具成本效益的GLYP污染土壤修复技术。该项目的总体目标是探索和研究电动生物降解(EK-Bio)作为一种有效的GLYP污染土壤修复技术的应用。提出的EK-Bio修复技术利用电场来增强土壤中污染物的生物降解。该项目的成功完成将通过产生新的基础知识、数据和建模工具来促进更有效和更具成本效益的土壤修复技术的设计和部署，从而使其能够在农业和农业中安全和可持续地使用，从而造福于社会。学生教育和培训将为社会带来更多好处，包括指导阿拉巴马大学的一名博士后研究员、一名研究生和一名本科生。作为一种潜在的草甘膦(GLYP)土壤修复技术，电动生物降解(EK-Bio)具有几个优点。首先，EK-Bio是一种原位技术，它利用电场来增强土壤中污染物的生物降解，包括低渗透土壤。其次，EK-Bio可以通过促进离子运动(如污染物、营养物质和电子供体/受体)和/或通过增加氧化还原酶的活性来促进GLYP在土壤中的生物降解，从而促进顽固性有机污染物的降解。第三，EK-Bio可以很容易地与其他技术(如土壤冲洗)相结合，以扩大其适用性并提高其有效性。在这个项目中，首席调查员(PI)建议对EK-Bio有潜力成为修复GLYP污染土壤的有效技术的假设进行评估。为了验证这一假设，PI提出了一项综合的实验和建模研究计划。本研究的具体目标是：1)在不同的环境和操作条件下，研究三种典型土壤中GLYP在EK-Bio过程中的降解特征；2)利用先进的分析化学工具和分子生物学技术探索和揭示GLYP降解的化学和生物学机制；以及3)开发和验证一个非局部反应传输模型来模拟EK-Bio过程中GLY的去向和传输。为了实现这个项目的教育和培训目标，PIS计划利用阿拉巴马大学(UA)的现有计划来招募和指导本科生从事项目研究活动。此外，PIS建议与阿拉巴马大学地区在职教育中心合作，提供两项年度教育活动，包括为从阿拉巴马州西部120多所学校挑选的高中生和教师提供身临其境的实验室演示，其中包括“科学家日”计划(秋季学期)和“荣誉日”计划(春季学期)。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Glyphosate is the most widely employed herbicide in the United States and globally. Approximately, 800,000 tons of glyphosate are utilized worldwide every year. Although the impact of glyphosate (GLYP) on human health is still the subject of ongoing debate, exposure to high concentrations of GLYP has been shown to 1) adversely impact ecosystem health including toxicity to several species in aquatic ecosystems and 2) contribute to the emergence of glyphosate-resistant crops, and herbicide resistance in weed populations. GLYP may also adversely impact soil quality and fertility, either through direct mechanisms such as complexation with metal ions that are essential to plant growth in soils, or through indirect mechanisms such as adversely affecting the growth and metabolism of mycorrhizae and earthworms, which can adversely impact plant access to nutrients and water infiltration in soils. In addition, GLYP accumulates in soils with limited (bio)degradation and mineralization through natural attenuation. Given the widespread use of GLYP, its potential ecosystem toxicity, and the limitations of natural attenuation, there is a critical need for more efficient and cost-effective remediation technologies for GLYP contaminated soils. The overarching goal of this project is to explore and investigate the utilization of electrokinetic biodegradation (EK-Bio) as an effective remediation technology for GLYP contaminated soils. The proposed EK-Bio remediation technology utilizes an electric field to enhance the biodegradation of contaminants in soils. The successful completion of this project will benefit society through the generation of new fundamental knowledge, data, and modeling tools to advance the design and deployment of more efficient and cost-effective technologies for the remediation of soils contaminated with GLYP to enable its safe and sustainable use in agriculture and farming. Additional benefits to society will be achieved through student education and training including the mentoring of a post-doctoral research fellow, one graduate student, and one undergraduate student at the University of Alabama.As a potential glyphosate (GLYP) soil remediation technology, electrokinetic biodegradation (EK-Bio) has several advantages. First, EK-Bio is an in-situ technology that utilizes an electric field to enhance the biodegradation of contaminants in soils including low-permeability soils. Second, EK-Bio can enhance the degradation of recalcitrant organic contaminants by enhancing ion movement (e.g., contaminants, nutrients, and electron donors/acceptors) and/or by increasing the activity of redox enzymes to enhance GLYP biodegradation in soils. Third, EK-Bio can easily be integrated with other technologies (e.g., soil flushing) to broaden its applicability and enhance its effectiveness. In this project, the Principal Investigators (PIs) propose to evaluate the hypothesis that EK-Bio has the potential to become an effective technology for the remediation of GLYP contaminated soils. To test this hypothesis, the PIs propose to carry out an integrated experimental and modeling research program. The specific objectives of the research are to 1) characterize GLYP degradation during EK-Bio under varying environmental and operating conditions in three model and representative soils; 2) probe and unravel the chemical and biological mechanisms of GLYP degradation using advanced analytical chemistry tools and molecular biology techniques; and 3) develop and validate a nonlocal reactive-transport model to simulate GLY fate and transport during an EK-Bio process. To implement the education and training goals of this project, the PIs plan to leverage existing programs at the University of Alabama (UA) to recruit and mentor undergraduate students to work on the project research activities. In addition, the PIs propose to partner with the University of Alabama Regional In-Service Education Center to deliver two annual education activities consisting of immersive lab demonstrations for high school students and teachers selected from over 120 schools in Western Alabama including a “Scientist for Day” program (Fall Semester) and a “Honor Day” program (Spring Semester).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.