Coupling of physical and bio-geochemical processes in saturated and unsaturated subsurface systems.

采矿、工业和其他人为活动造成的地下水污染威胁到饮用水供应和生态系统健康。污染物在地下水和非饱和土壤中的迁移和去向往往涉及复杂的生物地化反应以及物理迁移和衰减过程。反应迁移模型提供了量化这些过程的手段，提供了分析复杂数据集的手段，并提供了对污染物迁移和衰减的基本机制的洞察。这项研究的长期目标是通过开发反应迁移模型，更好地了解和量化耦合的生物地球化学和物理过程，以及这种耦合对污染物迁移和衰减的影响。发展的重点领域将包括：1)纳米粒子和胶体传输和反应的模拟：胶体是尺寸在纳米尺度上测量的粒子。无机和有机胶体可以与含金属废物相互作用，并有可能促进它们在环境中的运输。将开发一个反应输运模型来模拟胶体输运和地球化学相互作用，并将该模型用于模拟野外和实验室的柱实验，以更好地了解胶体相关的金属输运。2)多相体系中稳定同位素分馏的模拟：将建立一个反应输运模型来模拟甲烷中碳同位素的分馏和溶解和汽相气体中碳的分馏，包括气泡。该模型将用于模拟明尼苏达州贝米吉镇附近漏油地点的污染物降解过程，从而更好地了解污染物的降解速率以及迁移和衰减机制。此外，还将进行实验室水箱实验，以更好地量化地下水位中的气体/水相互作用。3)矿山废物物理和地球化学过程的耦合：预测废石堆的排水质量是矿山规划和许可的一个重要方面。将开发一个反应输运模型，以耦合废石场中的热、水文和地球化学相互作用。该模型将应用于西北地区Diavik钻石矿收集的数据，以更好地了解控制水质的过程。4)污染含水层中气体和气泡运动的力学模拟。将开发一个反应运移模型，以更好地描述气体运移，包括地下水中气泡的运动。该模型将被用来模拟1)挥发性有机污染物在地下水中的传输，包括由于浮力引起的气泡的垂直传输，2)氚和有机污染物在地下和低水平核废料储存库中的不饱和物质中的传输，以及3)在人工补给池下补给时气泡的捕获。拟议的研究将提供一个独特的反应传输模型，该模型将深入了解污染物在地下的移动。这一见解将有助于制定具有成本效益的污染物稳定和补救方案，帮助加拿大工业达到环境保护标准。这项研究将培训开发和应用数值模式的高素质人员，并使他们对污染物地球化学和补救科学有透彻的了解。这些受训人员将继续从事尖端研究或在工业领域工作，管理污染问题，并帮助加拿大公司保持在污染物修复行业的领先地位。

The contamination of groundwater from mining, industrial and other anthropogenic activities threatens potable water supplies and ecosystem health. The transport and fate of contaminants in groundwater and in unsaturated soils often involves complex biogeochemical reactions coupled to physical transport and attenuation processes. Reactive transport models provide a means of quantifying these processes, providing a means of analyzing complex data sets and providing insights into the underlying mechanisms of contaminant transport and attenuation. The long-term objectives of the research are to better understand and quantify coupled biogeochemical and physical processes, and the effect of this coupling on contaminant transport and attenuation, through the development of reactive transport models. The key areas for development will include: 1) Simulation of nano-particle and colloid transport and reactivity: Colloids are particles with dimensions measuring in the nano-meter scale. Inorganic and organic colloids can interact with metal-bearing wastes and potentially facilitate their transport in the environment. A reactive transport model will be developed to simulate colloid transport and geochemical interactions, and the model will be used to simulate field and laboratory column experiments to gain a better understanding of colloid-associated metal transport. 2) Simulation of stable isotope fractionation in multi-phase systems: A reactive transport model will be developed to simulate the fractionation of carbon isotopes in methane and carbon in dissolved and vapour phase gases, including gas bubbles. The model will be used to simulate the degradation of contaminants at an oil spill site near the town of Bemidji, MN, providing a better understanding of degradation rates, and transport and attenuation mechanisms. In addition, laboratory tank experiments will be conducted to better quantify the gas/water interactions at the water table. 3) Coupling of physical and geochemical processes in mine waste: The prediction of drainage quality from waste-rock piles is an important aspect of mine planning and permitting. A reactive transport model will be developed to couple thermal, hydrological and geochemical interactions in waste-rock dumps. The model will be applied to data collected at the Diavik Diamond Mine in the Northwest Territories to better understand the processes controlling water quality. 4) Mechanistic simulation of gases and gas bubble movement in contaminated aquifers. A reactive transport model will be developed to provide a better description of gas transport, including the movement of gas bubbles in groundwater. The model will be used to simulate 1) the transport of volatile organic contaminants in groundwater including the vertical transport of gas bubbles due to buoyancy, 2) tritium and organic contaminants in unsaturated materials below and low-level nuclear waste repository, and 3) the entrapment of gas bubbled during recharge below an artificial recharge pond. The proposed research will provide a unique reactive transport model that will provide insight into the movement of contaminants in the subsurface. This insight will aid in the development of cost-effective contaminant stabilization and remediation options that will assist Canadian industry in meeting environmental protection standards. The research will train highly qualified personnel in the development and application of numerical models and provide them with a thorough understanding of contaminant geochemistry and remediation science. These trainees will continue with cutting edge research or will work in industry, managing contamination issues and helping to maintain Canadian companies at the leading edge of the contaminant remediation industry.