Metal(loid) Sequestration by Natural Bacterial Sulfate Reduction and Field-Scale Biostimulation

1425004桑德斯金属（类）螯合天然细菌硫酸盐还原和现场规模的生物刺激砷是一种常见的金属污染物，发现在地下水从自然和人为来源。特别是，地下水的天然砷污染在世界许多地方对人类健康构成重大威胁。地下水中的砷可以通过硫化物生物矿物的吸附或共沉淀来去除或隔离，如果它们是天然形成的，或者可以通过化学方法去除。设计的？沉淀。拟议的研究包括本科生和研究生的教育和研究活动。该研究将使学生从EPSCoR状态到现场，实验室和建模研究的一个重要的环境健康问题。研究结果将对矿物学/地球化学、水文学、地质微生物学、生物修复和环境健康等广泛领域产生重大影响。研究结果将对缓解自然和工业场所的砷问题产生重大影响。研究结果将为工业界规划和实施具有成本效益的修复战略提供重要信息，以应对大量砷（和其他金属）污染的工业和军事场所。此外，由于天然砷污染是一个紧迫的问题，在美国，我们开发的优化的成本效益的生物修复技术可能会受益于许多受砷影响的发展中国家（孟加拉国，越南，柬埔寨，印度等）。本研究的首要目标是评估如何细菌活动，生物矿化，地球化学吸附一起工作，以消除砷从地下水在现场规模。为了实现研究目标，研究小组将在工业现场进行长期的现场注入实验，通过不稳定的水溶性有机碳和电子受体进行修正;并表征天然含水层环境中形成的硫化物生物矿物的污染物同化能力。该团队将把现场实验与实验室研究和地球化学建模相结合，以评估在不断变化的氧化还原条件下控制砷流动性和地下水地球化学的关键微生物活动和地球化学反应。这项研究提供了一个无与伦比的机会，监测自然衰减过程和评估潜在的补救工具。为了解决在理解天然含水层中砷封存的关键地球化学过程中的关键差距，拟议的研究将围绕三个问题：1）导致砷被去除的主要机制是什么？2)建议的生物刺激技术是否可以优化，以便在细菌代谢停止后，硫化铁生物矿物继续通过吸附螯合砷？3)自然微生物群落结构如何响应野外生物刺激而变化？拟议的研究将表征吸附和衰减（生物和非生物）的金属污染物，将发展更好地了解化学和生物过程的影响及其对污染物行为的相关速率，将开发工具来估计天然含水层的天然污染物吸收能力，还将开发地球化学方法，以确定在生物刺激后是否仍在发生自然衰减过程（并可能持续到未来）。

1425004SaundersMetal(loid) Sequestration by Natural Bacterial Sulfate Reduction and Field-Scale BiostimulationArsenic is a common metal contaminant found in groundwater from both natural and anthropogenic sources. In particular, natural arsenic contamination of groundwater poses a major human health threat in many parts of the world. Arsenic in groundwater may be removed or sequestered by adsorption or co-precipitation on sulfide bio-minerals if they form naturally or can be ?engineered? to precipitate. The proposed research includes educational and research activities for undergraduate and graduate students. The research will expose students from an EPSCoR state to field, laboratory, and modeling research on a significant environmental health problem. The results will be of great interest to the broad fields of mineralogy/geochemistry, hydrology, geomicrobiology, bioremediation, and environmental health. The results will have significant implications for mitigation of arsenic problems at both natural and industrial sites. The results will provide critical information to industry as they plan and implement cost-effective remediation strategy for the large number of arsenic (and other metals) contaminated industrial and military sites. Moreover, because natural As-contamination is a pressing problem worldwide, the optimized cost-effective bioremediation technology we develop in US may benefit many arsenic-affected developing countries (Bangladesh, Vietnam, Cambodia, India, etc.).The overarching objective of this study is to assess how bacterial activity, biomineralization, and geochemical sorption work together to remove arsenic from groundwater at the field scale. To achieve the research goal the research team will conduct long-term field injection experiments at an industrial site amended by labile water-soluble organic carbon and electronic acceptors; and, characterize contaminant assimilative capacity of sulfide biominerals formed in a natural aquifer setting. The team will integrate field experiments with lab-based studies and geochemical modeling to assess the key microbial activities and biogeochemical reactions that control arsenic mobility and groundwater geochemistry under changing redox conditions. This research offers an unparalleled opportunity to monitor the natural attenuation processes and evaluate a potential remediation tool. To address critical gaps in the understanding of key biogeochemical processes of arsenic sequestration in natural aquifers, the proposed study will center around three questions: 1) What is the main mechanism causing arsenic to be removed? 2) Can the proposed biostimulation technology be optimized so that the Fe-sulfide biominerals continue to sequester arsenic by sorption after bacterial metabolism ceases? 3) How does the natural microbial community structure change in response to biostimulation in the field? The proposed research will characterize sorption and attenuation (both biotic and abiotic) of metal contaminants, will develop a greater understanding of the effect of chemical and biological processes and their associated rates on contaminant behavior, will develop tools to estimate the natural contaminant assimilative capacity of natural aquifers, and also will develop geochemical methods to determine whether natural attenuation processes are still occurring after biostimulation (and will likely to continue into the future).