Comparative Study of Salt Leaching Dynamics at Different Water Temperatures: Sand and Clay Soils

Abstract

Many processes that dictate the movement of solutes through porous media are temperature-dependent.  In porous media systems, water temperature can induce a qualitative change in solute transport behavior within layers.  Nonetheless, the way they change soil salinity is still poorly quantified. This study aims to understand the impact of water temperature on hydraulic performance and salt leaching from sand and clay soils. The experiment was performed with eight columns containing sand and clay under four different water temperature conditions (25, 40, 60, and 80 °C). Results show that flow and leaching performance significantly increase with increasing water temperature. An increase in water temperature from 25 to 80 °C, sand flow rates increased from 4.62 (mL/min) to 6.87 (mL/min), and clay: from 2.70 (mL/min) to 6.18 mL/ min, respectively. In addition, soil salinity was remarkably reduced with rising temperature, where low EC values for sand (461 μS/cm) and clay (318 μS/cm) were reached at 80 °C. The enhanced mobilization of salts under increased thermal conditions was further supported by the trends observed in effluent conductivity. The results show that water temperature is a coupled driver of flow and solute release, with the efficacy being highly dependent on soil structure. Hence, an effective technique for salt leaching enhancement is thermal treatment, especially in low-permeable soils where conventional methods are hardly applicable.