Efficiency of Talcum-Biochars to Mitigate Heavy Metals and Growth of Brassica Chinensis in Contaminated Agricultural Soil

Abstract

Soil contamination with multiple heavy metals poses a significant threat to the global environment. This study aimed to evaluate the ability of a novel talcum-modified biochar as a soil amendment to improve soil properties and remediation performance in agricultural soils contaminated with various heavy metals. The talcum-biochar composites exhibited superior immobilization efficacy for multiple heavy metals compared to pristine biochar. CaCl2-heavy metal contents decreased under the treatment with talcum-biochar, in contrast to the control. Sequential extraction procedures revealed that the more accessible forms of heavy metals were converted into less accessible forms. The application of talcum-biochar reduced the Cu, Zn, Cr, and Cd concentrations in Brassica chinensis, potentially due to a decrease in their bioavailability in the soil. Following the addition of talcum-biochar composites, increases in soil pH, available P and K levels, total N content, and organic matter concentrations were observed. Additionally, a significant enhancement in catalase and urease activities was noted, whereas acid phosphatase activity was inhibited. The Cd content in B. chinensis and available Cd in the soil had a highly significant positive correlation with pH, physicochemical properties, soil enzyme activities, and the quantity of talcum added to the talcum-biochar composites. Therefore, the utilization of talcum-biochar composites as amendments has great potential for enhancing the soil environment and remediating multiple heavy metal-contaminated soils, making it an eco-friendly and cost-effective approach.

Keywords: biochar, Co-contaminated soils, soil stabilization, Brassica chinensis, Bioavailability