Thallium (Tl) is a highly toxic metal, and elevated concentrations in the environment have raised serious environmental and human health concerns. In this study, column leaching experiments coupled with the Convection-Dispersion Transport Fitting (CXTFIT) model and statistical analyses were used to investigate the mobility and retention of Tl(I) in diverse soil systems. Correlation analysis revealed that Tl(I) retention by soils was predominantly governed by soil pH, cation exchange capacity, exchangeable cations (K + , Na + , Ca 2+ , and Mg 2+ ), and free manganese oxides, which are reflected in the retardation factor (R f ). The forward-selection multiple linear regression model identified the key soil properties that collectively explained approximately 77% of the variance in Tl(I) mobility. Desorption experiments showed that K⁺ was the most effective competing cation for Tl(I) remobilization, achieving up to 93.0% desorption in specific soils. However, in soils with higher R f values, Tl(I) desorption by K⁺ was relatively limited (73.5%), suggesting potential persistence. Conversely, soils with lower R f values may release Tl(I) more readily when exposed to the solutions of K + or other cations, such as fertilizer application, thereby increasing the environmental risk. Overall, this study elucidates the physicochemical controls on Tl(I) transport and retention in soils, providing a quantitative framework for risk assessment and the design of soil-specific remediation strategies for soil Tl contamination. • Column experiments and CXTFIT modeling elucidated Tl(I) transport in 20 soils. • Transport parameters reveal non-equilibrium behavior with rate-limited sorption in high-retention soils. • Tl(I) retention depends mainly on soil pH, CEC, exchangeable cations, and Mn oxides. • K⁺ showed the highest Tl(I) desorption efficiency.
Lai et al. (Sun,) studied this question.