Soil pollution poses a direct threat to both the ecological environment and groundwater safety. Since pollutant transport in soil induces changes in diffusion-adsorption potential, understanding its characteristics is essential for effective pollution prevention and control. Red clay was investigated using the self-potential method. Representative pollutants, including sodium chloride solution, copper nitrate solution, and landfill leachate, were employed in laboratory experiments to examine the variation patterns of diffusion-adsorption potential generated by solute transport under different solute types and concentrations. The results indicate that the potential decrease immediately after the target solution infiltrate the soil and is detected by the electrodes, and the magnitude of the decrease is positively correlate with the solution concentration. During the diffusion of sodium chloride and copper nitrate solutions, anion accumulation on the high-concentration side causes a continuous potential decrease, whereas cation migration toward the low-concentration side resulte in a potential increase. For landfill leachate with a more complex composition, the potential variation pattern differe markedly from those of the two salt solutions. At saturated concentrations, the potential on the high-concentration side exhibite a pronounced downward trend, while under unsaturated conditions, potential variations similar to those in the salt solutions are observed, accompanied by a continuous potential decrease on the low-concentration side. These findings elucidate the self-potential response characteristics of three types of pollutants during their migration in red clay, thereby confirming the feasibility of the self-potential method for monitoring contaminant transport in red clay-covered areas and offering a theoretical foundation for early warning systems and prevention strategies against soil and groundwater pollution in such regions.