Purpose Saline-alkali soils, with high salt content, are important soil resources due to their significant production potential once the salts are removed. The ability to remove salts from saline-alkali soils depends on the saturated hydraulic conductivity (SHC), which is crucial for enhancing the sustainable development of saline-alkali land. The effect of electrostatic repulsion between soil particles, considering the polarization effects of interfacial counterions, on the SHC of saline-alkali soil was therefore investigated in different leaching electrolytes. Materials and methods The test saline-alkali soil samples (0–20 cm) were collected from Korla City, Xinjiang Province, China. The SHC was determined using the one-dimensional vertical water infiltration method with a constant head. The sieved soil was packed into Plexiglas columns (10 cm in diameter × 10 cm in height) at a target bulk density of 1.15 g cm− 3. The column experiments were carried out at room temperature (~ 298 K) and repeated twice. The electrokinetic potential of samples was measured using a zeta potential analyzer (ZetaPlus, Brookhaven Instruments) across a range of concentrations of different electrolytes. The soil samples were saturated with H+ before determining the cation exchange capacity under different pH conditions using a Micro-Nano Universal Surface Charge Analyzer (VSI-USCA2001, Chongqing Vision Scientific Instrumentation Co., Ltd.). Results and discussion The SHC decreased with decreasing electrolyte concentrations and showed the Hofmeister sequence K+ > Na+ and NO3− > CO32−. The concentrations and types of electrolytes determined the interfacial potential of soil particles, which further determined the electrostatic repulsions between soil particles and then directly affected the SHC of saline-alkali soil. The electrostatic repulsive pressures between soil particles, influenced by ionic polarizability, resulted in the observed Hofmeister sequence for the SHC under different electrolyte conditions. Although the SHCs were substantially different in Na/K carbonates and nitrates, they could be described as a function of electrostatic repulsion between soil particles. Soil water movement can be quantitatively predicted by soil internal electrostatic repulsion estimated by surface potential rather than zeta potential. Conclusion Our findings indicated that reducing the surface charge density of soil particles and the presence of strongly polarized ions in irrigation water can decrease electrostatic repulsion, leading to improved salt-leaching in saline-alkali soil.

Saturated hydraulic conductivities in saline-alkali soil dependent on electrostatic repulsion between particles considering polarization effects

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发表日期：

2025年3月7日

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Yanting Jing,
Wuquan Ding,
Xinmin Liu

摘要

Purpose

Saline-alkali soils, with high salt content, are important soil resources due to their significant production potential once the salts are removed. The ability to remove salts from saline-alkali soils depends on the saturated hydraulic conductivity (SHC), which is crucial for enhancing the sustainable development of saline-alkali land. The effect of electrostatic repulsion between soil particles, considering the polarization effects of interfacial counterions, on the SHC of saline-alkali soil was therefore investigated in different leaching electrolytes.

Materials and methods

The test saline-alkali soil samples (0–20 cm) were collected from Korla City, Xinjiang Province, China. The SHC was determined using the one-dimensional vertical water infiltration method with a constant head. The sieved soil was packed into Plexiglas columns (10 cm in diameter × 10 cm in height) at a target bulk density of 1.15 g cm^− 3. The column experiments were carried out at room temperature (~ 298 K) and repeated twice. The electrokinetic potential of samples was measured using a zeta potential analyzer (ZetaPlus, Brookhaven Instruments) across a range of concentrations of different electrolytes. The soil samples were saturated with H⁺ before determining the cation exchange capacity under different pH conditions using a Micro-Nano Universal Surface Charge Analyzer (VSI-USCA2001, Chongqing Vision Scientific Instrumentation Co., Ltd.).

Results and discussion

The SHC decreased with decreasing electrolyte concentrations and showed the Hofmeister sequence K⁺ > Na⁺ and NO₃⁻ > CO₃²⁻. The concentrations and types of electrolytes determined the interfacial potential of soil particles, which further determined the electrostatic repulsions between soil particles and then directly affected the SHC of saline-alkali soil. The electrostatic repulsive pressures between soil particles, influenced by ionic polarizability, resulted in the observed Hofmeister sequence for the SHC under different electrolyte conditions. Although the SHCs were substantially different in Na/K carbonates and nitrates, they could be described as a function of electrostatic repulsion between soil particles. Soil water movement can be quantitatively predicted by soil internal electrostatic repulsion estimated by surface potential rather than zeta potential.

Conclusion

Our findings indicated that reducing the surface charge density of soil particles and the presence of strongly polarized ions in irrigation water can decrease electrostatic repulsion, leading to improved salt-leaching in saline-alkali soil.