Quantification of the Impact of Hydrologic Controls on Anomalous Solute Transport and Mixing Dynamics in Partially Saturated Porous Media

当地下水在地下流动时，它与其他化学性质不同的水混合时经常发生化学反应，这可以促进污染物分解成危害较小的物质。这些混合和反应的关键过程受到非饱和条件的显著影响，在非饱和条件下，土壤和沉积层的孔隙中含有除水以外的其他相，例如空气或气体。该项目旨在调查和量化地下水文系统中不饱和条件对流动、运输和混合的影响。具体来说，该项目将在3d打印的土壤结构和新颖的数值模拟中使用新的实验成像方法来可视化和预测流体如何相互作用，并探索含水量的变化和多孔基质的物理特性如何影响混合和反应结果。总的来说，本研究将为水资源管理和推进水科学提供坚实的科学基础，确保地下水资源的保护和可持续性。此外，该项目将为各级学生提供有影响力的教育和培训机会，并辅以公众宣传和加强STEM教育的举措。该项目将开发和使用新的实验技术和数学模型，旨在了解部分饱和多孔介质中反应输运的复杂性。本研究以非饱和多孔介质中异常输运、混合和化学反应等相关现象为研究重点，结合孔尺度和达西尺度的视觉实验室实验和直接数值模拟进行了定量研究。主要目标包括：1)利用三维多孔介质的实验观测，研究流体动力学、介质非均质性和流体相分布对溶质输运和分散的影响。2)利用实验数据评估饱和度在促进反应热点和增强混合过程中的作用。3)利用反应输运模型中的孔隙尺度性质、流动和输运统计以及反应速率，对混合和反应进行力学描述和预测。该项目的结果将有助于改进对依赖化学品运输和混合到受污染地点的水资源污染的预测和管理。该奖项由水文科学项目和促进竞争研究的既定项目（EPSCoR）共同资助。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。

As groundwater moves through the subsurface, it often undergoes chemical reactions as it mixes with other chemically distinct waters, which can facilitate the breakdown of pollutants into less harmful substances. These critical processes of mixing and reaction are significantly influenced by unsaturated conditions, where soil and sediment layers contain phases other than water, such as air or gas, within their pores. This project aims to investigate and quantify how flow, transport, and mixing are impacted by unsaturated conditions in subsurface hydrologic systems. Specifically, the project will use new experimental imaging methods in 3D-printed soil structures and novel numerical simulations to visualize and predict how fluids interact and explore how variations in water content and the physical characteristics of the porous matrix influence mixing and reaction outcomes. Collectively, this research will provide a robust scientific foundation for water resource management and advancing water science, ensuring the protection and sustainability of groundwater resources. Moreover, the project will facilitate impactful educational and training opportunities for students across all levels, complemented by public outreach and initiatives to enhance STEM education. This project will develop and use novel experimental techniques and mathematical models aimed at understanding the complexities of reactive transport in partially saturated porous media. The research focuses on investigating and quantifying the interrelated phenomena of anomalous transport, mixing, and chemical reaction in unsaturated porous media, combining pore- and Darcy-scale visual laboratory experiments and direct numerical simulations. The primary objectives include: 1) Investigating the effects of flow dynamics, medium heterogeneity, and the distribution of fluid phases on solute transport and dispersion using experimental observations in three-dimensional porous media. 2) Utilizing experimental data to assess the role of saturation in promoting reaction hotspots and enhancing mixing processes. 3) Employing pore-scale properties, flow and transport statistics, and reaction rates in reactive transport models to mechanistically describe and predict mixing and reaction. The project results will be relevant for the improved prediction and management of contamination of water resources that rely on the transport and mixing of chemicals to target polluted locations.This award is co-funded by the Hydrologic Sciences program and Established Program to Stimulate Competitive Research (EPSCoR).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.