Remediation of Contaminated Soil in Pb-Zn Mining Area by Raw and Modified Tobacco Stem-derived Biochar
Tobacco stem biochar(BC)has been widely used in the remediation of heavy metal-contaminated soil,and its remediation effect is closely related to the preparation conditions and raw materials.Taking tobacco stem-derived biochar(BC)and its nano hydroxyapatite(nHAP)modified biochar(HBC)pyrolyzed at different temperatures(300,500 and 700 ℃)as research objects,the microcosmic cultivation experiment was used to explore the passivation and remediation effects of tobacco stem BC and HBC on Pb and Zn contaminated soil in mining areas at different periods(7,14 and 30 days).The results showed that BC and HBC prepared at differ-ent temperatures could increase soil pH to 7.81-8.56,and significantly reduce the leaching concentration of soil Pb by 30.02％-34.75％and 28.23％-34.02％,respectively;and the soil available Pb decreased by 37.95％-51.71％and 22.56％-26.52％,re-spectively,while the soil available Zn decreased by 31.90％-55.52％and 19.31％-41.70％,respectively.The bioavailability of Pb and Zn decreased most significantly after 7 days of incubation.Different BC reduced the acid soluble state of Pb and Zn by 8％-11％and 6％-14％,respectively,and meanwhile,increased the reducible state,oxidizable state and residual state of Pb and Zn.HBC,on the other hand,promotes the transformation of acid soluble and reducible Pb and Zn into oxidizable state and residual states.The reme-diation effect of BC on soil Pb and Zn is equivalent to that of HBC.Therefore,tobacco stem-derived BC and HBC have significant effects in passivating Pb and Zn contaminated soil in mining areas,which can provide scientific basis for soil pollution remediation in mining areas.
soils in Pb-Zn mining areatobacco stem-derived biocharmodificationmobilitygeochemical formsbioavailability
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