Characterization and Simulation of the Effects of Redox Zones on the Fate and Transport of Contaminants in the Saturated Subsurface

9506467 洛阿格 人为污染可以产生不同氧化还原电位的地球化学带，这反过来又会导致许多有害污染物以不同的氧化态存在于不同的含水层带中。 这些污染物在不同氧化态下的迁移率可以按数量级变化。 这使得预测地下水污染物的迁移、归宿和影响的任务变得非常复杂。 这里提出的工作将提供深入了解的命运和运输的危险化学品在饱和地下。 这项工作将建立一个基于物理和化学的模拟协议，使未来的工作人员能够定量估计可能以多种氧化态存在的污染物的命运和运输。 经过充分研究的美国地质勘探局有毒物质水文研究计划现场科德角，MA将作为一个独特的数据集模型开发和测试。 这项工作的预期结果包括：i）负责在科德角现场观察到的Fe（II）分布的反应的表征，ii）在当前和未来的管理策略下，铁和缺氧区的潜在命运。 在这项研究中的科德角网站所使用的措施和模型的方法将作为一个替代未来的调查在类似的污染网站。 拟议工作将采取的办法包括三个阶段。 第一阶段将通过以下方式完成：i）基于热力学开发一组控制铁浓度的化学反应，以及ii）分析批次模拟对反应物和产物的浓度和丰度的敏感性。 第二阶段将完成调查过程中影响Fe（II）在科德角网站的运输过程中，i）构建一个一维模型来模拟污水羽流和铁区的发展和ii）考虑限速反应的重要性和影响。 在第三阶段，化学批量建模和一维传输建模将被集成，以开发耦合的地下水流，化学形态，溶质运移在科德角油田现场的模型。 第三阶段将通过以下方式完成：i）开发二维垂直横截面地下水流模型; ii）开发二维垂直横截面地下水溶质运移模型; iii）耦合流体流动和溶质运移模型。 这些模拟将与现场数据进行比较，以评估耦合建模方法的概念开发和预测能力方面的模型性能。

9506467 Loague Anthropogenic contamination can create geochemical zones of different redox potential, which in turn will cause many hazardous contaminants to exist in different oxidation states in different zone of aquifers. The mobilities of these contaminants in the different oxidation states may vary by orders of magnitude. This greatly complicates the task of predicting the transport, fate and effects of groundwater contaminants. The work proposed here will provide insight into the fate and transport of hazardous chemicals in the saturated subsurface. This work will establish a physics and chemistry based simulation protocol that will enable future workers to quantitatively estimate the fate and transport of contaminants that can exit in multiple oxidation states. The well-studied USGS Toxic Substances Hydrology Research Program field site on Cape Cod, MA will serve as a unique data set for model development and testing. The results anticipated from this work include i) characterization of the reactions responsible for the distribution of Fe (II) observed at the Cape Cod site and ii) the potential fate of the iron and anoxic zone under current and future management strategies. The measure and model approach used for the cape Cod site in this study will serve as a surrogate for future investigations at similar contaminations sites. The approach to be taken for the proposed work consists of three phases. The first phase will be accomplished by i) developing a set of chemical reactions, based upon thermodynamics, that control the concentration of iron, and ii) analyzing the sensitivity of batch simulations to concentrations and abundances of reactants and products. The second phase will be accomplished by investigating what processes affect Fe (II) during transport at the Cape Cod site by i) constructing a one-dimensional model to simulate the development of the sewage plume and iron zone and ii) considering the importance and impact of rate-limited reactions. In third p hase the chemical batch modeling and the one-dimensional transport modeling will be integrated to develop a model of coupled groundwater flow, chemical speciation, and solute transport at the Cape Cod field site. The third phase will be accomplished by i) developing a two-dimensional vertical cross-sectional groundwater flow model, ii) developing a two-dimensional vertical corss-sectional groundwater solute transport model, and iii) coupling the fluid flow and solute transport models. These simulations will be compared with field data to evaluate model performance in terms of assessing concept development and predictive capabilities of the coupled modeling approach.