CAREER: Hydrodynamic Controls on Fluid and Solute Exchanges Across the Aquifer-Estuary Interface

由于潮汐、波浪、水流和其他水文过程，地表水和溶解的化学物质在河流和海洋下面的沉积物中循环。在沉积物中，溶解的化学物质，如有机碳和硝酸盐，在重新进入地表水之前经历了化学转化。这种循环影响河流和海洋水质、生态系统健康和沿海地下水资源。该项目将利用地表水、地下水流动和生物地球化学计算机模型，量化并绘制三种类型河口陆海过渡带的水和化学交换以及盐水入侵的地图。这项研究将通过实地学习和通过与区域州际契约的伙伴关系提供的关于地下水-地表水相互作用的专业发展课程，纳入一个面向来自代表性不足社区的高中学生的多步骤教育管道。对地下水-地表水的尺度以及河流和海洋系统之间相关的化学交换的了解有限。该项目将通过解决河口地下水-地表水交换中河流和海洋连通性的基本问题来填补这一知识空白。该研究将开发新的地表水、地下水和反应输运耦合建模方法，以了解河口水动力学和地表水化学非均质性在驱动含水层-河口界面流体和化学交换中的作用。了解河流到海底的交换将有助于更准确地估计流入海洋的营养物质、金属、污染物和碳通量，从而将对海底交换的了解与陆地河流走廊的交换联系起来。深入了解地下水-地表水交换的水动力控制将有助于1)预测海平面上升对河口孔隙水化学转化的影响，2)改进沿海地表水质量模型，3)指导沿海地下水资源管理，4)加强研究河口的长期修复工作。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Surface water and dissolved chemicals cycle through sediments that underlie rivers and the ocean due to tides, waves, currents, and other hydrological processes. Within the sediments, dissolved chemicals, such as organic carbon and nitrate, undergo chemical transformations before re-entering surface water. This cycling affects river and ocean water quality, ecosystem health, and coastal groundwater resources. This project will quantify and map water and chemical exchanges and saltwater intrusion along the land-sea transition zone in three types of estuaries using surface water, groundwater flow, and biogeochemical computer models. The research will be integrated into a multi-step educational pipeline for high school students from underrepresented communities in the hydrologic sciences though field-based learning, and professional development courses on groundwater-surface water interactions that will be offered through partnership with a regional interstate compact. There is limited understanding of the scales of groundwater-surface water and associated chemical exchanges between river and ocean systems. The project will fill this knowledge gap by addressing fundamental questions on the connectedness of rivers and oceans through groundwater-surface water exchanges in estuaries. The research will develop new coupled surface water, groundwater, and reactive transport modeling approaches to understand the role of estuary hydrodynamics and heterogeneity in surface water chemistry on driving fluid and chemical exchanges across aquifer-estuary interfaces. Knowledge of river to seabed exchanges will allow for more accurate estimates of nutrient, metal, contaminant, and carbon fluxes to the ocean, thus bridging understanding of subsea exchanges to exchanges in terrestrial river corridors. Insights into hydrodynamic controls on groundwater-surface water exchanges will 1) aid in predicting the impacts of sea level rise on chemical transformations in estuarine pore water, 2) improve coastal surface water quality models, 3) guide coastal groundwater resource management, and 4) strengthen long-standing restoration efforts in the study estuaries.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.