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Environ Sci Pollut Res (2012) 19:12601270 DOI 10.1007/s11356-011-0648-4
RESEARCH ARTICLE
Use of inorganic and organic wastes for in situ immobilisation of Pb and Zn in a contaminated alkaline soil
Y-F. Zhou & R. J. Haynes & R. Naidu
Received: 9 August 2011 /Accepted: 18 October 2011 /Published online: 12 November 2011 # Springer-Verlag 2011
AbstractPurpose 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 CaCl2, CH3COOH, HCl and EDTA-extractable Zn but compost and mill mud had no appreciable immobilising effects. Additions of all amendments reduced levels of CaCl2, CH3COOH 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.
Keywords Metal immobilisation . Metal fixation . Heavy metals . Extractable metals
1 Introduction
Contamination of soils with heavy metals (e.g. Pb and Zn) is of environmental concern because the accumulated metals may adversely affect soil ecology, agricultural production, product quality, animal and human health as well as groundwater quality (Adriano 2001). The traditional method of treating heavy metal-contaminated soil is to excavate it and transport it to landfill. Processes have also...