Immobilization of Cadmium in Neutral Soil in a Vegetable Cultivation Mode Using Thiolated Palygorskite

Abstract

Cd pollution in agricultural soil and its subsequent accumulation in crops are a global concern. In situ immobilization is an efficient remediation method; however, there are only few reported amendments for neutral soil. In this study, thiolated palygorskite (TPAL) is employed as a potential amendment. To comprehensively investigate the remediation effects and associated mechanisms of TPAL, a pot‐scale cultivation experiment with pakchoi and romaine lettuce is conducted. TPAL reduces the available Cd concentrations in the soil by 38.12–57.54% at doses of 0.1–0.3% and subsequently decreases Cd accumulation in the leafy vegetables. TPAL clearly decreases the ζ potentials of the amended soil and increases their maximum sorption capacity to promote Cd fixation in the soil. Correlation and principal component analyses confirm that the immobilization effect is correlated with the maximum sorption capacity of the soil for Cd2+. Furthermore, TPAL reduces the biological concentration factors to inhibit the transfer of Cd from the soil to the roots of the vegetables. TPAL increases the vegetable biomass and has no elevating effects on the soil pH or available concentrations of trace elements in the soil, illustrating its environmental friendliness. Overall, TPAL is a good immobilization amendment for Cd‐contaminated neutral soils.