Effects of sodium adsorption ratio and electrolyte concentration on soil saturated hydraulic conductivity
Effects of sodium adsorption ratio and electrolyte concentration on soil saturated hydraulic conductivity
复制标题
钠吸附率和电解质浓度对土壤饱和导水率的影响
DOI：
10.1016/j.geoderma.2022.115772
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发表时间：
2022-02-18
期刊：
影响因子：
6.1
通讯作者：
Li, Hang
中科院分区：
文献类型：
--
作者：
Liu, Xinmin;Zhu, Yingcan;Li, Hang
钠吸附比（SAR）和电解质浓度（EC）会显著影响土壤中的水分运动。然而，其背后的理论机制却鲜有研究。在本研究中，推导出了钠 - 钙混合电解质溶液或土壤水中静电斥力（PEDL）与SAR/EC之间的解析函数。土壤水的SAR和EC通过两个相邻土壤颗粒之间的表面电位和中点电位控制PEDL，进而影响饱和土壤导水率（Ks）。理论计算表明，PEDL随EC的增加而降低，随SAR的增加而升高，并且Ks的降低与斥力PEDL相关。使用了五种具有不同主要黏土矿物（特别是高岭石（K）、伊利石（I）和蒙脱石（M））的土壤来研究PEDL与Ks变化之间的关系。将这些土壤装入柱中，并用一系列SAR从0增加到无穷大的溶液（EC值分别恒定为0.5、1和2 ds m⁻¹）进行淋洗。我们的研究表明，Ks随PEDL的增加而降低。在Ks降低百分比（Kred）与PEDL曲线的拐点处，芒加纳土壤（M）、亚兰杜土壤（M，K）和邓霍尔姆土壤（M）的临界PEDL值为8.358 - 8.569 atm，且Kred > 92%，而厄布拉土壤（I）和廷伯利土壤（K）的平均临界PEDL值约为12.34 atm，Kred仅约为51.75%。对于给定的土壤，PEDL是决定性因素，而其他因素如土壤质地和黏土类型也会影响Ks。
Sodium adsorption ratio (SAR) and electrolyte concentration (EC) can significantly affect water movement in soil. However, the theoretical mechanisms behind it are rarely studied. In the present study, an analytical function between electrostatic repulsive pressure (PEDL) and SAR/EC was derived in Na-Ca mixed electrolyte solutions or soil water. Soil water SAR and EC controls PEDL through surface potential and midpoint potential between two adjacent soil particles, which consequently influences the saturated soil hydraulic conductivity (Ks). Theoretical calculations show that the PEDL decreases with increasing EC and increases with increasing SAR, and the reduction in Ks is correlated with the repulsive PEDL. Five soils of different dominant clay minerals, specifically kaolinite (K), illite (I) and montmorillonite (M), were used to investigate the relationship between PEDL and change of Ks. The soils were packed in columns and leached with a serial of solutions (constant EC values of 0.5, 1, and 2 ds m-1, respectively) with increasing SAR from 0 to infinity. Our study showed that the Ks decreases with increasing PEDL. At the inflection point of the percent of Ks reduction (Kred) vs. PEDL curve, the critical PEDL values are 8.358 ~ 8.569 atm and Kred > 92% for the Mungana soil (M), Yarrandoo soil (M, K) and Dunholm soil (M), while the average critical PEDL value is about 12.34 atm and Kred is only ~51.75% for the Urrbrae soil (I) and Timberlea soil (K). For a given soil, the PEDL is the determinant factor, while other factors such as soil texture and clay type can also affect Ks.