Remediation of soil contaminated by copper, cadmium and lead combined with agroforestry matrix biochar and Vetiver zizanioides

The effects of adding rice husk biochar (DBC), coconut husk biochar (YBC) and corn stalk biochar (JBC) on the basic soil properties, the morphological distribution of Cu, Cd and Pb in soil, and the contents of Cu, Cd and Pb in different parts of Vetiver zizanioides were studied by pot experiment. The results showed that both biochar application alone and biochar combined with Vetiver zizanioides treatment increased soil pH value and organic matter content, and soil urease, sucrase and catalase activities increased to varying degrees. The total amount of Cu, Cd and Pb in soil decreased after biochar application alone or combined with Vetiver zizanioides treatment. During the three incubation periods, the proportion of available Cu and Pb in soil decreased, the proportion of residual Cu and Pb increased, and the proportion of residual Cd first decreased and then increased. The addition of biochar significantly reduced the accumulation of Cu, Pb and Cd in Vetiver zizanioides root. Biochar is beneficial to the stabilization of Cu, Cd and Pb in the root of Vetiver zizanioides and reduce the effective state of Cu, Cd and Pb in soil, and can be applied to the remediation of soil contaminated by Cu, Cd and Pb.