title: Chemical stabilisation of lead in shooting range soils with phosphate and magnesium oxide: Synchrotron investigation.
abstract: Three Australian shooting range soils were treated with phosphate and magnesium oxide, or a combination of both to chemically stabilize Pb. Lead speciation was determined after 1 month ageing by X-ray absorption spectroscopy combined with linear combination fitting in control and treated soils. The predominant Pb species in untreated soils were iron oxide bound Pb, humic acid bound Pb and the mineral litharge. Treatment with phosphate resulted in substantial pyromorphite formation in two of the soils (TV and PE), accounting for up to 38% of Pb species present, despite the addition of excess phosphate. In MgO treated soils only, up to 43% of Pb was associated with MgO. Litharge and Pb hydroxide also formed as a result of MgO addition in the soils. Application of MgO after P treatment increased hydroxypyromorphite/pyromorphite formation relative to soils teated with phosphate only. X-ray diffraction and Scanning electron microscopy revealed PbO precipitate on the surface of MgO. Soil pH, (5.3-9.3) was an important parameter, as was the solubility of existing Pb species. The use of direct means of determination of the stabilisation of metals such as by X-ray absorption spectroscopy is desirable, particularly in relation to understanding long term stability of the immobilised contaminants.
authors.affiliation: Centre for Environmental Risk Assessment and Remediation and CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), University of South Australia, University Parade, 5095 Mawson Lakes, Australia.
authors.forename: Peter
authors.initials: P
authors.lastname: Sanderson
authors.affiliation: Centre for Environmental Risk Assessment and Remediation and CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), University of South Australia, University Parade, 5095 Mawson Lakes, Australia. Electronic address: ravi.naidu@crccare.com.
authors.forename: Ravi
authors.initials: R
authors.lastname: Naidu
authors.affiliation: Centre for Environmental Risk Assessment and Remediation and CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), University of South Australia, University Parade, 5095 Mawson Lakes, Australia.
authors.forename: Nanthi
authors.initials: N
authors.lastname: Bolan
authors.affiliation: Korea Biochar Research Center & Department of Biological Environment, Kangwon National University, Chuncheon 200-701, South Korea.
authors.forename: Jung Eun
authors.initials: JE
authors.lastname: Lim
authors.affiliation: Korea Biochar Research Center & Department of Biological Environment, Kangwon National University, Chuncheon 200-701, South Korea.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Ok
mesh_terms: D005389:Firearms; D007854:Lead / Q000737:chemistry*; D008277:Magnesium Oxide / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010710:Phosphates / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*; D017356:Synchrotrons; D014961:X-Ray Diffraction
chemical_list: D010710:Phosphates; D012989:Soil Pollutants; D007854:Lead; D008277:Magnesium Oxide
keywords: Bioavailability; Immobilisation; Lead; Linear combination fitting; X-ray adsorption spectroscopy