Abstract:Soil in mining areas are easily to be contaminated by heavy metals, which fact is a major challenge for land resource utilization and maintenance. In the present study, the contaminated soil in copper mining area was used as the research material, and 0, 1%, 2%, 4%, and 10% (w/w) biochar were added by weight ratio to carry out an indoor potted experiment for planting Vetiveria zizanioides. The effects of biochar on soil pH and microbial activity, and the enrichment and transport of heavy metals by Vetiveria zizanioides were investigated to find out the correlations between the contents of heavy metal species, biochar and microbial activity, aiming to provide a theoretical reference for the combined remediation of heavy metal-contaminated soil in mining areas by biochar and Vetiveria zizanioides. The results showed that the addition of biochar increased soil pH, significantly increased the activities of soil FDA hydrolase, sucrase and urease, and significantly promoted soil basal respiration, but had no significant effect on soil microbial biomass carbon. The addition of biochar significantly increased the biomass of Vetiveria zizanioides, decreased the available state of Cu and Pb, while the changes of Cd species was opposite. The addition of high doses of biochar attenuated the enrichment of Cu in Vetiveria zizanioides, while the addition of biochar promoted the enrichment of Cd and Pb and attenuated the transport of Cu, Cd and Pb in Vetiveria zizanioides. So Vetiveria zizanioides could be used as a stabilized plant for Cu, Cd and Pb. Soil sucrase activity was significantly positively correlated with the contents of Cu, Cd and Pb in leaves, soil available state Cu and residual state Cu; soil basal respiration was significantly negatively correlated with the contents of Cu, Cd and Pb in leaves, available state Cu and available state Pb, while significantly positively correlated with available state Cd. In conclusion, biochar can reduce the toxic effect of heavy metals on the growth of Vetiveria zizanioides in mining soil and promote the enrichment of heavy metals by Vetiveria zizanioides, and the combination of both can improve the physicochemical properties and microbial activity of contaminated soil in copper mining areas. These findings are conducive to the remediation of heavy metal-contaminated soil and the improvement of soil quality.