Subsurface Carbon Cycling in Bioremediation of Acid Mine Drainage: Experiments and Modeling

酸性矿山排水生物修复中的地下碳循环：实验和建模

• 批准号: 0854510
• 负责人: JoAnn Silverstein
• 金额: $ 33.91万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0854510&HistoricalAwards=false
• 关键词: Subsurface; Carbon; Cycling; Bioremediation; Acid

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).0854510SilversteinAcid Mine Drainage (AMD) is a serious environmental problem resulting from oxidation reactions in sulfidic rock, which is mediated by iron-oxidizing bacteria (IOB). The principal objective of this proposal is to develop a fundamental quantitative understanding of the coupled biogeochemical processes involved in the pyrite oxidation cycle and the carbon cycle, facilitating the evaluation and design of a sustainable remediation process. The proposed work is a follow-up to previously-funded bench-scale studies of the use of organic carbon additions for mitigation of AMD, which demonstrated that addition of organic carbon to acid generating rock stimulates the growth of heterotrophic microorganisms, consuming oxygen and sequestering ferric iron, thus inhibiting pyrite oxidation. The proposed research, which combines experiments and modeling across a range of scales, consists of the following major tasks: (1) Monitor reactions of AMD generation and inhibition under simulated environmental conditions for sufficient duration to determine mineral and organic carbon storage and transport from the interstitial pore to waste rock pile scale. (2) Develop expressions for microbial and chemical kinetics and diffusion rates in waste rock to use in computational models. (3) Characterize transport and storage of reactive organic and mineral constituents along flow paths in waste rock media over the range of spatial and temporal scales, to evaluate the sustainability of carbon addition for in-situ AMD remediation. (4) Incorporate the understanding gained from (1) - (3) into a rigorous reactive transport model and combine it with models of complex unsaturated flow in waste rock systems to predict the behavior at the waste-rock column and pile scale. (5) Carry out sensitivity analysis to evaluate the robustness of carbon addition in inhibiting AMD formation in waste rock under a variety of environmental and hydrologic conditions. The remediation strategy being explored in this project for in-situ control of AMD generation can potentially result in significant reduction in cost compared with current approaches. Moreover, the study of carbon addition to waste rock is an opportunity to identify the mechanisms that control carbon cycling in the subsurface after perturbation of an existing biogeochemical system. Once developed, the multi-scale model approach could be used to assess sustainability of other bioremediation methods such as constructed wetlands and bioreactive subsurface barriers. The multi-disciplinary nature of the research will provide unique opportunities for graduate student research and training in environmental engineering - with broad exposure to hydrology, geochemistry, microbiology and modeling. Large lab columns will provide educational and outreach opportunities targeted at undergraduate students, stakeholder groups and K-12 students in Colorado, where the environmental impacts of AMD are widespread. A diverse group of undergraduate student researchers will be recruited through the University of Colorado REU site in environmental engineering and the Summer Multicultural Access to Research and Training (SMART) program.

该奖项根据 2009 年《美国复苏和再投资法案》（公法 111-5）提供资金。0854510银矿酸性矿山排水 (AMD) 是由含铁氧化细菌 (IOB) 介导的硫化岩石中的氧化反应引起的严重环境问题。该提案的主要目标是对黄铁矿氧化循环和碳循环中涉及的耦合生物地球化学过程有一个基本的定量理解，促进可持续修复过程的评估和设计。这项拟议的工作是先前资助的使用有机碳添加物缓解AMD的小规模研究的后续工作，该研究表明，向产酸岩石中添加有机碳会刺激异养微生物的生长，消耗氧气并隔离三价铁，从而抑制黄铁矿氧化。拟议的研究结合了一系列尺度的实验和建模，包括以下主要任务：（1）在模拟环境条件下监测AMD生成和抑制的反应足够长的时间，以确定矿物和有机碳从间隙孔到废石堆规模的储存和运输。 (2) 开发废石中微生物和化学动力学以及扩散速率的表达式，以用于计算模型。 (3) 在时空尺度范围内表征废石介质中反应性有机成分和矿物成分沿着流动路径的传输和储存，以评估原位 AMD 修复中碳添加的可持续性。 （4）将从（1）-（3）中获得的理解纳入严格的反应输运模型，并将其与废石系统中复杂的非饱和流动模型相结合，以预测废石柱和堆规模的行为。 (5)进行敏感性分析，评价在各种环境和水文条件下添加碳对抑制废石中AMD形成的稳健性。该项目中正在探索的用于 AMD 生成的原位控制的修复策略与当前方法相比可能会显着降低成本。此外，对废石中碳添加的研究为确定现有生物地球化学系统扰动后控制地下碳循环的机制提供了一个机会。一旦开发出来，多尺度模型方法可用于评估其他生物修复方法的可持续性，例如人工湿地和生物反应性地下屏障。该研究的多学科性质将为环境工程研究生的研究和培训提供独特的机会——广泛接触水文学、地球化学、微生物学和建模。大型实验室专栏将为科罗拉多州的本科生、利益相关团体和 K-12 学生提供教育和推广机会，AMD 的环境影响在科罗拉多州非常普遍。科罗拉多大学环境工程 REU 网站和夏季多元文化研究与培训 (SMART) 项目将招募多元化的本科生研究人员。