Effect of Particle Size on Droplet Infiltration into Hydrophobic Porous Media As a Model of Water Repellent Soil

详细信息    查看全文

• 作者：Christopher A. E. Hamlett ; Neil J. Shirtcliffe ; Glen McHale ; Sujung Ahn ; Robert Bryant ; Stefan H. Doerr ; Michael I. Newton.
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：November 15, 2011
• 年：2011
• 卷：45
• 期：22
• 页码：9666-9670
• 全文大小：769K
• 年卷期：v.45,no.22(November 15, 2011)
• ISSN：1520-5851

文摘

The wettability of soil is of great importance for plants and soil biota, and in determining the risk for preferential flow, surface runoff, flooding,and soil erosion. The molarity of ethanol droplet (MED) test is widely used for quantifying the severity of water repellency in soils that show reduced wettability and is assumed to be independent of soil particle size. The minimum ethanol concentration at which droplet penetration occurs within a short time (鈮?0 s) provides an estimate of the initial advancing contact angle at which spontaneous wetting is expected. In this study, we test the assumption of particle size independence using a simple model of soil, represented by layers of small (0.2鈥? mm) diameter beads that predict the effect of changing bead radius in the top layer on capillary driven imbibition. Experimental results using a three-layer bead system show broad agreement with the model and demonstrate a dependence of the MED test on particle size. The results show that the critical initial advancing contact angle for penetration can be considerably less than 90掳 and varies with particle size, demonstrating that a key assumption currently used in the MED testing of soil is not necessarily valid.