Project 4: Arsenic and Manganese Mobility: Land Use, Redox Shifts

在过去十年中，我们对砷和锰污染含水层的静态地球化学特征有了详细的了解，并在孵育实验中表征了沉积物对人工化学扰动的快速反应。然而，人们对水文地质学的基本方面所知甚少，而这些方面对于理解受这些金属污染的流动路径上地下水化学的演变至关重要。我们不知道驱动锰和砷流动性的溶质通量是如何进入含水层的，地下水流动的模式是什么，或者溶质是如何在不同的流动路径上混合的。对深层地下水流动的了解甚少，区域流动的意义、地下水抽取等基本问题仍存在争议。在拟议的研究中，我们将把传感器网络和地球物理成像技术与三维地下水流动和输送模型结合起来，以表征不断变化的地下条件。我们将观察通过安装社区供水井（提供安全用水的最常见方法）如何改变地下条件，我们将开发地下水化学未来变化的预测模型。我们的研究结果将提供深入了解导致金属从沉积物中动员的过程，并将更好地管理受污染的地下水。

Over the last decade we have gained a detailed understanding of the static geochemical characteristics of arsenic and manganese contaminated aquifers and have characterized the rapid response of sediment to artificial chemical perturbations in incubation experiments. However, remarkably little is known about the basic aspects of hydrogeology that are vital for understanding the evolution of groundwater chemistry along flow paths that are contaminated by these metals. We do not know how the solute fluxes that drive manganese and arsenic mobility enter the aquifer, what patterns groundwater flow follows, or how solutes mix across different flow paths. Little is known about deeper groundwater flow, and basic issues such as the significance of regional flow and groundwater pumping are still controversial. In the proposed research, we will combine networks of sensors and geophysical imaging techniques with three-dimensional groundwater flow and transport models to characterized changing subsurface conditions. We will observe how subsurface conditions may be altered by installation of community supply wells, the most common approach to providing safe water, and we will develop predictive models for future shifts in groundwater chemistry. Our results will provide insight into the processes that cause metal mobilization from sediments, and will enable better management of contaminated groundwater.