The Role of Fractional Dynamic Wettability as a Primary Determinant for Flow and Transport in Soils and the Vadose Zone.

分数动态润湿性作为土壤和包气区流动和传输的主要决定因素的作用。

• 批准号: RGPIN-2014-04214
• 负责人: Smith, James
• 金额: $ 2.19万
• 依托单位: McMaster University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633877
• 关键词: Role; Fractional; Dynamic; Wettability; Primary

In some soils when water is applied to the surface by rain or other means the water beads on the surface and runs off. Then, over time the soil changes to become able to soak up the water. This process is called dynamic fractional wettability or soil water repellency. Dynamic fractional wettability drastically changes the behaviour of water and its availability in soils for plant growth, nutrient cycling, and it role in contaminant transport. The process of changing wettability of soils is very complex and unpredictable under many important environmental conditions. For example, after a forest wildfire the soil is commonly rendered highly repellent leading to excessive runoff of rain with resultant erosion. Also, the amount of water that is retained in repellent soil is greatly reduced which directly affects plant growth, seed germination, soil evapotranspiration, and soil temperature. Water that does pond on the surface due to the repellency can drain down fractures and large pores in the soil (like old root channels) and bypass the shallow soil and most plant roots to subsequently arrive in groundwater much more quickly. Similar concerns of dynamic fractional wettability below ground surface occur in soils after petroleum spills or at old industrial sites (Brown Fields). Unfortunately, our current scientific knowledge and ability to predict how water moves and is stored or released from soils that have the tendency to repel water to varying degrees over time (dynamic fractional wettability) is critically lacking. The current state of our scientific knowledge is such that there are currently no mechanistic computer models that can accurately describe water behaviour in these complex dynamic soils and/or resultant recharge and transport of contaminants to ground waters under these conditions. Research over the last few decades has revealed that soil water fractional wettability/repellency is far more common than previously known/recognised and is potentially a primary driver for water movement under a number of important environmental conditions. The objectives of this NSERC Discovery Grant research program are to advance our fundamental conceptual understanding and ability to mathematically model and predict water flow and contaminant transport in soils expressing dynamic fractional wettability/water repellency. This will be done through field experiments, highly instrumented laboratory testing/experiments, pore-scale imaging in representative soil materials, and model development. The outcome will be new/better models of soil water flow, soil water storage, and related contaminant transport in soil and groundwater that can be used to help solve many related and pressing environmental problems subject to the primary effects of dynamic fractional wettability.

在某些土壤中，当通过雨水或其他方式将水施加到表面时，水会在表面形成水珠并流走。然后，随着时间的推移，土壤发生变化，能够吸收水分。这个过程称为动态分数润湿性或土壤拒水性。动态分数润湿性极大地改变了水的行为及其在土壤中对植物生长、养分循环及其在污染物输送中的作用的可用性。在许多重要的环境条件下，土壤润湿性的变化过程非常复杂且不可预测。例如，森林野火之后，土壤通常会变得高度排斥，导致雨水径流过多，从而导致侵蚀。而且，憎水土壤中的保水量大大减少，直接影响植物生长、种子发芽、土壤蒸散和土壤温度。由于排斥性而在地表积聚的水可以从土壤中的裂缝和大孔隙（如旧根通道）中排出，并绕过浅层土壤和大多数植物根部，随后更快地到达地下水。类似的地表以下动态分数润湿性问题也出现在石油泄漏后或旧工业场地（布朗田）的土壤中。不幸的是，我们目前严重缺乏科学知识和预测水如何从土壤中移动、储存或释放的能力，这些土壤随着时间的推移会不同程度地排斥水（动态分数润湿性）。我们科学知识的现状是，目前没有机械计算机模型可以准确描述这些复杂动态土壤中的水行为和/或在这些条件下由此产生的补给和污染物向地下水的输送。过去几十年的研究表明，土壤水分数润湿性/排斥性比以前已知/认识的要普遍得多，并且可能是许多重要环境条件下水运动的主要驱动因素。 NSERC 发现补助金研究计划的目标是提高我们对基本概念的理解以及对表达动态分数润湿性/防水性的土壤中的水流和污染物传输进行数学建模和预测的能力。这将通过现场实验、高度仪器化的实验室测试/实验、代表性土壤材料的孔隙尺度成像以及模型开发来完成。结果将是土壤水流、土壤水储存以及土壤和地下水中相关污染物迁移的新的/更好的模型，可用于帮助解决许多受动态分数润湿性主要影响的相关和紧迫的环境问题。