Impact of manganese-driven redox processes on groundwater quality and soil carbon cycling

地下水资源的保护和温室气体的排放是加拿大乃至全世界的关键环境问题。土壤在这些挑战中发挥着核心作用。我在氧化还原生物地球化学方面的研究项目的主要目标是了解地下水污染的威胁，并产生对土壤中碳封存的矿物控制的机制理解-土壤是生物圈中最大的动态陆地碳库。通过使用多学科方法，拟议的研究计划解决了两个基本问题：(i)矿物质（例如，锰氧化物），微生物和有机物之间的相互作用如何控制威胁地下水质量的氧化还原活性地质污染物？（ii）锰氧化物在土壤碳循环中的作用是什么？锰氧化物是环境系统中最活跃的矿物相之一，几乎影响每一个元素循环。锰不仅被认为是对水生和土壤系统中污染物和碳动态的重要控制，而且越来越多地被认为是饮用水中出现的一种污染物。本研究项目的目的是为了更好地了解土壤中锰的动态循环，以便提供安全的饮用水和优化土壤中的碳固存。拟开展的研究包括以下三个方面：(1)确定地下水中锰释放的物理和生物地球化学控制；(2)评价锰、碳在控制成因砷动员的地球化学过程中的竞争效应；(3)定量Mn氧化物对复合有机C化合物的非生物转化。研究结果将为改善对有地质污染风险的地下水资源的管理提供有价值的信息。对重要的地下水资源进行天然污染物调查对于减少公众接触和确定易受监测和管理的地区至关重要，以便防止代价高昂的污染物动员。除了帮助更有效地分配管理资源外，拟议的研究还将为控制地下过程提供有价值的见解，以尽量减少未来来自自然来源的地下水污染。这些结果将为水资源管理者提供有关含水层地质或成土和生物地球化学过程是否能更好地预测地下水污染的宝贵信息。最后，研究锰氧化物促进碳矿化的程度将提高预测环境变化和土地管理转变如何影响二氧化碳释放的准确性。提高对土壤循环的矿物控制的理解对于确保加拿大实现《巴黎协定》中承诺的2030年减排目标至关重要，特别是考虑到最近的quamebe立法要求到2020年完全禁止垃圾填埋场的有机物。

The preservation of groundwater resources and the release of greenhouse gases represent critical environmental issues in Canada and worldwide. Soils play a central role in these challenges. The main goals of my research program in redox biogeochemistry are to understand groundwater contamination threats and to generate mechanistic understanding of mineral control on carbon sequestration in soils - the largest dynamic terrestrial carbon reservoir in the biosphere. By using a multidisciplinary approach, the proposed research program addresses two essential questions: (i) How do interactions among minerals (e.g., manganese oxides), microorganisms, and organic matter control redox-active geogenic contaminants which threaten groundwater quality? and (ii) What is the role of manganese oxides in soil carbon cycling? Manganese oxides are among the most reactive mineral phases in environmental systems and influence nearly every elemental cycle. Not only is Mn gaining recognition as an important control on both contaminant and carbon dynamics in aquatic and soil systems, but it is increasingly recognized as a contaminant of emerging concern in drinking water. The objective of this research program is to develop a better understanding of the dynamic cycling of Mn in soils, in order to provide safe drinking water and optimize carbon sequestration in soils. The proposed research addresses the following three axes: (1) Identifying physical and biogeochemical controls on Mn release in groundwater; (2) Evaluating competitive effect of Mn and C on geochemical processes controlling mobilization of geogenic As; and (3) Quantifying the abiotic transformation of complex organic C compounds by Mn oxides. The results will provide valuable information for the improved management of groundwater resources that are at risk of geogenic contamination. Surveying vital groundwater resources for native contaminants is critical to reduce public exposure and identify vulnerable areas for monitoring and management in order to prevent costly contaminant mobilization. In addition to helping allocate management resources more efficiently, the proposed research will provide valuable insight into controlling subsurface processes in order to minimize future groundwater contamination from natural sources. These results will provide water managers valuable information on whether aquifer geology or pedogenic and biogeochemical processes serve as better predictors of groundwater contamination. Finally, investigating the extent to which Mn oxides promote C mineralization will improve the accuracy of predicting how environmental changes and shifts in land-management may impact CO2 release. This improved understanding of mineral control on soil  cycling will be critical to ensure Canada reaches its 2030 emission reduction targets as committed to in the Paris agreement, especially in light of recent Québec legislation that calls for a complete ban of organic matter from landfills by 2020.