Remediation Effect of Compound Modifier FZB on Arsenic and Cadmium Contaminated Soil

A pot-based planting experiment of Chinese brassica was carried out to study the influence of the compound modifier FZB (iron sulfate+zeolite+modified biochar) on the physical and chemical properties of soil, As and Cd bioavailability and morphology, and the ability of Chinese brassica to accumulate As and Cd at different dosages. The results showed that, after application of FZB, the pH, OM, and CEC contents of the rhizosphere soil tended to increase in As and Cd compound contaminated farmland soils. The concentrations of available As and available Cd in the soil gradually reduced with an increase in FZB application, with maximum reductions of 65.99% and 30.68%, respectively. The application of FZB significantly changed the morphology of heavy metals in the soil, which consequently decreased the exchangeable concentrations of As and Cd, while the concentrations of aluminum-bound As, iron-bound As, organic bound Cd, and residual Cd increased. At the same time, the application of FZB effectively reduced the concentrations of As and Cd in the roots and aerial parts of Chinese brassica. When 8 g·kg-1 of FZB was applied, compared with the control group, the concentrations of As and Cd in the aerial parts of Chinese brassica were reduced by 42.09% and 31.34%, respectively. FZB application decreased the As and Cd bioaccumulation capacity of the roots and aerial parts, and decreased the capacity of the plant to translocate As from the roots to the aerial parts. The study shows that the composite modifier FZB has good application prospects for reducing the bioavailability of As and Cd in farmland soils.