Effects of freeze-thaw leaching on physicochemical properties and cadmium transformation in cadmium contaminated soil

作者：Lulu Wu, Wei Du, Luping Wang, Yang Cao, Jialong Lv · 发表于：Ecotoxicology and Environmental Safety · 年份：2024 · DOI：10.1016/j.ecoenv.2024.116935 · 被引用次数：18 · 研究领域：Climate change and permafrost、Agriculture, Soil, Plant Science、Soil and Unsaturated Flow

This study aims to investigate the effect of the combined method of freeze–thaw and leaching on the removal of cadmium (Cd) in soil and to provide a theoretical basis for the remediation of farmland soil polluted by heavy metals. The removal process and mechanism of Cd were deduced through oscillatory leaching experiments and freeze–thaw leaching simulation experiments, and the influence of the freeze–thaw leaching technology on the soil environment was evaluated. The results of oscillatory leaching showed that a mixture consisting of 0.80 mol/L citric acid and 0.80 mol/L ferric chloride in a 1:19 vol ratio effectively remove 47.75 % of Cd, indicating that the composite leaching agent could effectively remove Cd from the soil. The results of the freeze–thaw leaching simulation experiment showed that although the freeze–thaw leaching treatment increased the total Cd content in the 0–5 cm soil layer, the total Cd content in the 5–10 cm, 10–15 cm, and 15–20 cm soil layers decreased by 5.08 %, 2.39 %, and 5.68 %, respectively. The freeze–thaw leaching increased the content of exchangeable Cd ( p<0.05 ), carbonate bound Cd, but decreased organic bound Cd and residual Cd ( p<0.05 ), thereby increasing the bioavailability of Cd. Freeze–thaw leaching not only increased the competitive adsorption of Cd 2+ by decreasing soil pH, cation exchange capacity, and increasing the content of exchangeable calcium and exchangeable magnesium, thus reducing the adsorption of Cd in soil. And the re...