Mechanism of Water and Salt Migration in soil during Cyclic Freeze-thaw

摘要

Water migration during freeze-thaw is influenced by temperature gradient, initial moisture content, concentration gradient and soil structure. Temperature gradient is one of the external agents of the soil water movement. Water is not only the solvent of salt, but also carrier of the salt, so salt migration is influenced by factor influencing water movement besides various physical and physicochemical matters. So the mechanism of water movement determines a large extent the mechanism of salt migration. Salt migration is controlled by concentration gradient and temperature gradient. Salt migrates with water for convection accompanying diffusion for concentration gradient.