Mobility and Fate of Potentially Toxic Elements in Soil Environment

Abstract

Soil pollution, caused by potentially toxic elements (PTEs), is a significant problem worldwide. This study has investigated the key factors that control the mobility and fate of six PTEs (Pb, Cd, Cr, Cu, Zn, and Ni) which are frequently detected in contaminated soils. The findings of this study demonstrate that smaller particles present in soil show stronger adsorption capacity compared to larger particles because of the higher specific surface area. Moreover, soil with higher organic matter content (e.g., humic acid) exhibits stronger adsorption capacity due to the presence of abundant functional groups namely hydroxyl (─OH) and carboxyl (─COOH). Notably, these functional groups possess high affinity for Pb adsorption, followed by Cd > Cu > Cr > Zn > Ni. The adsorption of most of the PTEs by soil with and without humic acid is better described by the Langmuir isotherm model and pseudo‐second‐order kinetic model. Overall, the experimental results illustrate that soil with high contents of humic acid can restrict the mobility of PTEs. This mechanistic evaluation predicts how soils with different organic matter contents respond to PTEs pollution. This study outcome will be helpful in developing sustainable remediation strategies to tackle pollution caused by PTEs in the soil environment.