Upscaling of Reactive Transport Equations in Porous Media; Biologically Mediated Iron Reduction, and the Effect of Humic Materials on the Scaling Process

JaffeIron还原影响许多重要的多孔介质过程（即，磷酸盐或砷酸盐等化合物的吸附，或与铁还原同时发生的铀还原），因此需要铁还原动力学的预测能力，并且是该项目的重点。 铁还原可以通过腐殖物质的存在来增强，腐殖物质可以充当电子表，即使当铁还原剂不与铁表面直接接触时也允许反应发生。 通过关注溶解腐殖物质存在和不存在下的铁还原，本研究将深入了解腐殖物质如何影响整体铁还原动力学。 它还将提供一个独特的实验系统，其中（i）反应取决于与铁表面直接接触的铁还原细菌的生物量（无腐殖酸），和（ii）铁还原细菌的所有生物量都参与反应，受到电子调度过程（含腐殖酸）的传输限制，并且应应用新的缩放方程。 我们将在石英砂中进行一系列的柱实验，不同的铁分布，乙酸盐作为碳源。 将用铁还原剂接种色谱柱，并在有AQDS（腐殖物质类似物）和无AQDS的情况下一式两份运行。 将获得所有色谱柱实验的本体反应速率，并与通过缩放程序获得的速率进行比较。 这项研究的结果可以转移到，例如，在湿地，地下水微量金属/放射性核素补救，砷酸盐和磷酸盐的稳定性的生物地球化学动力学的模型模拟。 这项研究将涉及一名兼职博士后研究员，以及研究生和本科生，并将导致开发一个实验模块，重点是高中生物和化学教师在土壤中的地球化学反应。

0337687 JaffeIron reduction affects many important porous media processes (i.e., sorption of compounds such as phosphates or arsenate, or the reduction of uranium, which occurs simultaneously with iron reduction) therefore predictive capabilities of iron reduction dynamics are needed and are the focus of this project. Iron reduction can be enhanced by the presence of humic substances that can act as an electron schedule, allowing the reaction to happen even when the iron reducer is not in direct contact with the iron surface. By focusing on iron reduction in the presence and absence of dissolved humic substances, this research will gain an insight on how humic substances affect the overall iron reduction kinetics. It will also provide a unique experimental system where (i) the reaction is dependent on the biomass of the iron reducing bacteria directly in contact with the iron surface (no humics), and (ii) all biomass of the iron reducing bacteria is involved in the reaction, subject to the transport limitations of the electron schedule process (with humics), and for which new scaling equations should apply. We will conduct a series of column experiments in quartz sand with varying iron distributions, and acetate as the carbon source. The columns will be seeded with an iron reducer and will be run in duplicate, with AQDS (a humic substance analog) and without AQDS. Bulk reaction rates will be obtained for all column experiments, and compared to the rates obtained via the scaling procedure. Results of this research can be transferred, for example, to model simulations of the biogeochemical dynamics in wetlands, groundwater trace metal/radionuclide remediation, arsenate and phosphate stability. This research will involve a part-time postdoctoral fellow, as well as graduate and undergraduate students, and will result in the development of an experimental module focused on biogeochemical reactions in soils for high school biology and chemistry teachers.