title: Long-term impact of biochar on the immobilisation of nickel (II) and zinc (II) and the revegetation of a contaminated site.
abstract: A field remediation treatment was carried out to examine the long-term effect of biochar on the immobilisation of metals and the revegetation of a contaminated site in Castleford, UK. The extracted concentrations of nickel (Ni) (II) and zinc (Zn) (II) in the carbonic acid leaching tests were reduced by 83-98% over three years. The extracted Ni (II) and Zn (II) concentrations three years after the treatment were comparable to a cement-based treatment study carried out in a parallel manner on the same site. The sequential extraction results indicated that biochar addition (0.5-2%) increased the residue fractions of Ni (II) (from 51% to 61-66%) and Zn (II) (from 7% to 27-35%) in the soils through competitive sorption, which may have resulted in the reduction of leachabilities of Ni (II) (from 0.35% to 0.12-0.15%) and Zn (II) (from 0.12% to 0.01%) in the plots with biochar compared with that without biochar three years after the treatment. The germination of grass in the plots on site failed. Further laboratory pot study suggested that larger amounts of biochar (5% or more) and compost (5% or more) were needed for the success of revegetation on this site. This study suggests the effectiveness and potential of biochar application in immobilising heavy metals in contaminated site in the long term.
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom. Electronic address: ztshennju@gmail.com.
authors.forename: Zhengtao
authors.initials: Z
authors.lastname: Shen
authors.affiliation: UniKL MICET, Lot 1988 Bandar Vendor Taboh Naning, Melaka, 78000 Alor Gajah, Malaysia.
authors.forename: Amelia Md
authors.initials: AM
authors.lastname: Som
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom.
authors.forename: Fei
authors.initials: F
authors.lastname: Wang
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom.
authors.forename: Fei
authors.initials: F
authors.lastname: Jin
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom.
authors.forename: Oliver
authors.initials: O
authors.lastname: McMillan
authors.affiliation: Geotechnical and Environmental Research Group, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ, United Kingdom.
authors.forename: Abir
authors.initials: A
authors.lastname: Al-Tabbaa
mesh_terms: D002606:Charcoal / Q000737:chemistry*; D052918:Environmental Restoration and Remediation / Q000379:methods*; D009532:Nickel / Q000032:analysis* / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry; D015032:Zinc / Q000032:analysis* / Q000737:chemistry
chemical_list: D012989:Soil Pollutants; C540010:biochar; D002606:Charcoal; D009532:Nickel; D015032:Zinc
keywords: Biochar; Heavy metal; Leaching; Revegetation; Sequential extraction; Soil remediation