title: Use of inorganic and organic wastes for in situ immobilisation of Pb and Zn in a contaminated alkaline soil.
abstract: OBJECTIVE
  This study aims to examine whether addition of immobilising agents to a sandy, alkaline (pH = 8.1) soil, which had been contaminated with Pb and Zn by airborne particles from a Pb/Zn smelter, would substantially reduce metal bioavailability.
  
  
  METHODS
  The effectiveness of five waste materials (blast furnace (BF) slag, alum water treatment (WT) sludge, red mud, sugar mill mud and green waste compost) as metal immobilising agents was evaluated by incubating them with a contaminated soil for a period of 12 months at rates of 5% and 10% (w/w), after which, Rhodes grass was grown in the soils in a greenhouse study.
  
  
  RESULTS
  Additions of WT sludge, BF slag and red mud reduced CaCl(2), CH(3)COOH, HCl and EDTA-extractable Zn but compost and mill mud had no appreciable immobilising effects. Additions of all amendments reduced levels of CaCl(2), CH(3)COOH and HCl-extractable Pb although concentrations of EDTA-extractable Pb remained unchanged. A sequential extraction procedure showed that additions of mill mud and compost increased the percentage of total Pb and Zn present in the oxidisable fraction whilst additions of the other materials increased the percentage present in the residual fraction. Rhodes grass yields were promoted greatly by additions of red mud, compost and particularly mill mud, and yields were negatively correlated with tissue Pb concentrations and extractable Pb.
  
  
  CONCLUSIONS
  Red mud was the most effective material for lowering extractable Pb and Zn levels simultaneously while mill mud and compost were notably effective for Pb. A field evaluation in the study area is justified.
authors.affiliation: School of Land, Crop and Food Sciences/CRC CARE, The University of Queensland, St Lucia, Queensland 4072, Australia.
authors.forename: Y-F
authors.initials: YF
authors.lastname: Zhou
authors.forename: R J
authors.initials: RJ
authors.lastname: Haynes
authors.forename: R
authors.initials: R
authors.lastname: Naidu
mesh_terms: D001682:Biological Availability; D005591:Chemical Fractionation; D052918:Environmental Restoration and Remediation / Q000379:methods*; D007220:Industrial Waste; D007854:Lead / Q000737:chemistry* / Q000493:pharmacokinetics; D008669:Metallurgy; D006109:Poaceae / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D012722:Sewage / Q000737:chemistry; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000737:chemistry* / Q000493:pharmacokinetics; D013021:South Australia; D015032:Zinc / Q000737:chemistry* / Q000493:pharmacokinetics
chemical_list: D007220:Industrial Waste; D012722:Sewage; D012987:Soil; D012989:Soil Pollutants; D007854:Lead; D015032:Zinc
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