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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=665459
• 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，当水通过雨水或其他方式施加到表面时，水在表面上形成水珠并流失。然后，随着时间的推移，土壤发生变化，能够吸收水分。这个过程被称为动态部分润湿性或土壤防水性。动态分数润湿性极大地改变了土壤中水的行为及其在植物生长、养分循环和污染物迁移中的作用。在许多重要的环境条件下，改变土壤润湿性的过程是非常复杂和不可预测的。例如，在森林野火之后，土壤通常呈现高度排斥性，导致雨水的过度径流，从而导致侵蚀。此外，保留在斥水土壤中的水量大大减少，这直接影响植物生长、种子萌发、土壤蒸散和土壤温度。由于排斥性，在表面上形成池塘的水可以沿着土壤中的裂缝和大孔隙（如旧的根通道）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。石油泄漏后的土壤或旧工业用地（棕色地带）也存在类似的地表以下动态湿润度问题。不幸的是，我们目前的科学知识和能力，以预测水如何移动，并存储或释放的土壤，有排斥水的趋势，随着时间的推移（动态分数润湿性）是严重缺乏。我们的科学知识的当前状态是这样的，目前没有机械的计算机模型，可以准确地描述在这些复杂的动态土壤和/或由此产生的补给和运输的污染物在这些条件下的地下沃茨中的水的行为。过去几十年的研究表明，土壤水分的润湿性/排斥性比以前已知/公认的要普遍得多，并且可能是许多重要环境条件下水分运动的主要驱动因素。 这个NSERC发现补助金研究计划的目标是推进我们的基本概念理解和数学建模的能力，并预测水流和污染物在土壤中的传输表示动态分数润湿性/防水性。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和模型开发来完成。其结果将是新的/更好的模型，土壤水流动，土壤水储存，以及相关的污染物在土壤和地下水中的传输，可用于帮助解决许多相关的和紧迫的环境问题的主要影响的动态分数润湿性。