Effect of modified corn residue biochar on chemical fractions and bioavailability of cadmium in contaminated soil

Abstract

ABSTRACT In order to study the effects of FeCl2 modified corn residue biochar (Fe-MCB) on the bioavailability and chemical fractions of cadmium (Cd) in a contaminated calcareous soil, an experiment was conducted as a factorial in completely randomised design with three replications. This research investigated two factors: levels of Cd concentration (0, 15, and 30 mg kg−1) and type of biochar [control: without any biochar application, biochar (CB) and Fe-MCB]. Results indicated that the use of CB and Fe-MCB increased soil pH, the cation exchange capacity (CEC) of soil and soil organic matter content (SOM). The application of CB and Fe-MCB significantly decreased Cd bioavailability by 26.52 and 37.75%, respectively. The results of sequential extraction showed that the exchangeable and carbonate fractions of Cd decreased while organically bounded Cd and Fe/Mn-oxide-bounded Cd increased after Fe-MCB was applied. The application of Fe-MCB increased the IR values, but decreased MF values, demonstrating a decrease in the mobility of Cd in the soil. Overall, this study showed that Fe-MCB application especially at high concentrations of Cd can effectively immobilise Cd, thus decreasing its mobility in contaminated soils and improving the quality of soil environment and reducing remediation costs.