Remediation effect of biochar-plant on heavy metal contaminated soil in mining area

Abstract

Pot experiment was carried out to artificially add different concentrations (0%, 5%, 10%) of swine biochar and fruit biochar in heavy metal contaminated soil in the farmland of the mining area to study the repairing effect on heavy metal contaminated soil. The results showed that the total Cu of the tested soil before planting was 166.51 mg/kg, the average Cd was 1.31 mg/kg, the average Pb was 757.78 mg/kg, and the average Hg was 8.43 mg/kg, which was a mixed contaminated soil of mercury, lead, cadmium and copper. The contents of Hg and Pb of the tested soils decreased after planting 4 plants, and Cd content decreased in addition to the CK group. The Cu content in the Z10 group decreased, but Hg content still exceeded the soil risk control value, the Cu, Cd and Pb contents exceeded the risk screening value, and the potential risk was reduced but still existed. Compared with CK treatment, the two biochars have better remediation effects on the 4 heavy metals in the tested soil, and the swine biohar was better than the fruit biochar. With the increase of the concentration of the two biochars, the repair effect was better. In the combined pollution soil, the overall remediation effect of biochar-plant combined restoration on these four heavy metals was Hg > Pb > Cd > Cu, and Z10-pakchoi had the best repair effect on Hg, Pb and Cu in the tested soil. Z10-spinach had the best effect on the repair of Cd.