Resistivity responses of sodium sulfate and sodium chloride-type loess under different water and salinity conditions

Saline loess is widely distributed in Africa, Latin America and Asia and is characterized by wet expansion and dry shrinkage, which has a large impact on the environment. In this study, the electrical resistivity of sodium sulfate loess and sodium chloride loess with moisture content (8-24%) and salt content (0.3-2.7%) was measured by an LCR digital bridge instrument. The experimental results demonstrated a decrease in the resistivity with the increase in moisture and salt content. When the salt content was greater than 0.9%, the rate of reduction in resistivity decreased and showed a tendency to be stable. With the increase in moisture content, the water conductive path changes from water in diffusion double layer (DDL) to capillary water and finally to gravity water, which in turn leads to a gradual decrease in the rate of reduction in resistivity. At the same salt content, the resistivity of sulfate loess is higher than that of chloride loess. This study analyses the resistivity changes of two kinds of salt-bearing loess under different water and salinity conditions, which has certain guiding significance for environmental monitoring and pollutant assessment based on resistivity data.