How does drying-driven crystalized salt influence the dynamics of water evaporation from porous media?

干燥驱动的结晶盐如何影响多孔介质中水蒸发的动力学？

• 批准号: 497539130
• 负责人: Professor Nima Shokri
• 金额: --
• 依托单位: Mork Family Department of Chemical Engineering and Materials Science
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/497539130?language=en
• 关键词: How; does; drying; driven; crystalized

Soil salinization, referring to excess accumulation of soluble salts in soil, has detrimental impacts on crops, animal and human health. It is one of the main land-degrading threats influencing soil fertility, stability, and bio-diversity leading to undesirable changes in the physical, chemical, and biological functions of the soil. Beyond soil, it has significant impacts on other processes such as the durability of building materials, preservation of pavements, and CO2 sequestration. Saline water evaporation is influenced by transport properties of the porous media, external conditions (e.g. wind, ambient temperature, and relative humidity), properties of the evaporating solution, and salt crystallization. During water evaporation from soil, solute is transported via capillary induced liquid flow, from the wet zone at the bottom to the evaporation surface. Simultaneously, diffusion tends to spread the solute homogeneously across the entire domain. The competition between upward advection and diffusion transport determines solute distribution throughout the soil. When advection dominates diffusion, solute in preferentially deposited close to the surface leading to gradual increase of its concentration. When salt concentration substantially exceeds the solubility limit, crystals will precipitate at soil surface. The crystals formed at the surface create complex, branching structures, which can substantially increase the surface area available for evaporation. How exactly the presence of the evolving evaporation-driven porous crystallized salt at the surface influences the evaporative water losses from soil under different boundary conditions is poorly understood. Detailed information about the complex coupling between flow and transport processes within porous media and the evolving crystallized salt at the surface is required for accurate prediction of water evaporation from soil otherwise our description of this process would reply on adjusting parameters. Without such knowledge, one may notably underestimate or overestimate water availability and evaporation from land surface which will influence several hydrologic processes. In this project, we plan to conduct a comprehensive multiscale numerical and experimental investigations to quantify the effects of the evolving evaporation-driven crystallized salt at the surface on the evaporative water loses from porous media. Within this context, we will utilize the state-of-art numerical and experimental tools such as molecular dynamics simulation, pore-network and continuum-scale modelling, synchrotron X-ray micro-tomography and customized laboratory experiments to achieve the objectives of this project. Such efforts will enable us to provide an accurate description of saline water evaporation which will place us in a stronger position to quantify soil water evaporation and land-atmosphere interactions.

土壤盐碱化是指土壤中可溶性盐的过量积累，对农作物、动物和人类健康产生不利影响。它是影响土壤肥力、稳定性和生物多样性的主要土地退化威胁之一，导致土壤物理、化学和生物功能发生不良变化。除了土壤之外，它还对建筑材料的耐久性、路面的保存和二氧化碳封存等其他过程产生重大影响。盐水蒸发受到多孔介质的传输特性、外部条件（例如风、环境温度和相对湿度）、蒸发溶液的特性和盐结晶的影响。在水从土壤蒸发的过程中，溶质通过毛细管引起的液体流从底部的潮湿区域输送到蒸发表面。同时，扩散倾向于使溶质均匀地分布在整个域中。向上的平流和扩散传输之间的竞争决定了溶质在整个土壤中的分布。当平流主导扩散时，溶质优先沉积在靠近表面的位置，导致其浓度逐渐增加。当盐浓度大大超过溶解度极限时，晶体会在土壤表面沉淀。表面形成的晶体形成复杂的分支结构，可以大大增加可用于蒸发的表面积。地表不断演化的蒸发驱动多孔结晶盐的存在如何影响不同边界条件下土壤的蒸发水损失，人们知之甚少。为了准确预测土壤中的水蒸发，需要有关多孔介质内的流动和传输过程以及表面不断演变的结晶盐之间复杂耦合的详细信息，否则我们对该过程的描述将依赖于调整参数。如果没有这样的知识，人们可能会明显低估或高估水的可用性和陆地表面的蒸发，这将影响一些水文过程。在该项目中，我们计划进行全面的多尺度数值和实验研究，以量化表面不断变化的蒸发驱动结晶盐对多孔介质蒸发水损失的影响。在此背景下，我们将利用分子动力学模拟、孔隙网络和连续尺度建模、同步加速器X射线显微断层扫描和定制实验室实验等最先进的数值和实验工具来实现该项目的目标。这些努力将使我们能够准确描述盐水蒸发，这将使我们能够更好地量化土壤水蒸发和陆地-大气相互作用。