Effect of bone char addition on the fractionation and bio-accessibility of Pb and Zn in combined contaminated soil

Effect of bone char addition on the fractionation and bio-accessibility of lead (Pb) and Zinc (Zn) in combined contaminated soil was studied by batch soil column incubation experiment. Four treatments were designed: control (without bone char), 1%, 2% and 5% bone char addition (by weight). The results showed that all treatments with bone char addition could significantly decrease the concentration of HOAc extractable Pb (P < 0.05). Compared with the control the concentration of HOAc extractable Pb was decreased by 66.85%, 83.69% and 97.40%, respectively, in 1%, 2% and 5% bone char amended soils after 3 months incubation. The treatment with 5% bone char addition significantly decreased (P < 0.05) the concentration of HOAc extractable Zn by 47.80%, 43.63% and 41.35%, respectively, after 1, 2 and 3 months incubation. All treatments, including 1%, 2% and 5% bone char addition, significantly decreased (P < 0.05) the concentration of bio-accessible Pb after 3 months incubation, however, only the treatment with 5% bone char addition significantly decreased (P < 0.05) the concentration of bio-accessible Zn after 3 months incubation. The results highlighted the potential of bone char amendments to reduce the bioavailability of Pb and Zn in contaminated soil.