Abstract: Leaching is a simple and efficient way of soil restoration, but the effect on soil of low permeability is unsatisfactory. In view of this, electrokinetic remediation was taken to promote the efficiency of leaching of cadmium-contaminated paddy soils , and the influence of electrolyte pH control on the pH value of soil and the removal of heavy metal Cd was discussed in this paper. Results showed that when voltage gradient is 1.5 V/cm, working for five days intermittently and 8 hours every day continuously, the removal efficiency of Cd in electrokinetic leaching(Ex1) reached 50.87%, 10% higher than test Ex0 which was only simple leaching; electrokinetic remediation could strengthen the flow of pore water in the soil, accelerate the migration of Cd²⁺ in pore water of soil, improve the removal rate of Cd, and effectively promote the leaching effect of Cd in farmland soil. Compared with test Ex1 in which electrolyte pH was uncontrolled, tests Ex2, Ex3, and Ex4 could control the soil’s pH value and improve the mobility efficiency of Cd²⁺ in pore water of soil. Therefore, when factors such as site operation were considered, polarity switching technology would be a good choice in controlling soil’s pH value.

Key words: paddy soil, cadmium, leaching-electrokinetic, electrolyte pH control, polarity switching