In situ remediation and phytotoxicity assessment of lead-contaminated soil by biochar-supported nHAP

In this study, a kind of biochar-supported nano-hydroxyapatite (nHAP@BC) material was used in in-situ remediation of lead-contaminated soil. Column experiments were performed to compare the mobility of nHAP@BC and Bare-nHAP. The immobilization, accumulation and toxic effects of Pb in the after-amended soil were assessed by the in vitro toxicity tests and pot experiments. The column experiments showed a significant improvement in the mobility of nHAP@BC. The immobilization rate of Pb in the soil was 74.8% after nHAP@BC remediation. Sequential extraction procedures revealed that the residual fraction of Pb increased by 66.6% after nHAP@BC remediation, which greatly reduced the bioavailability of Pb in the soil. In addition, pot experiments indicated that nHAP@BC could effectively reduce the upward translocation capacity of Pb in a soil-plant system. The concentration of Pb in the aerial part of the cabbage mustard was 0.1 mg/kg, which is lower than the tolerance limit (0.3 mg/kg). nHAP@BC can remediate Pb-contaminated soil effectively, which can restore soil quality for planting.