Distribution and nature of arsenic along former railway corridors of South Australia
Date
2006
Authors
Smith, E.R.G.
Smith, J.
Naidu, R.
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Science of the Total Environment, 2006; 363(1-3):175-182
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Elevated concentrations of arsenic (As) have been detected in soils of former railway corridors in South Australia, Australia. Elevated As concentrations resulted from the long-term application of As-based herbicides to control grass growth along former railway corridors. A study of former railway corridors revealed considerable surface (0-10 cm) contamination with As (< 20 to > 1000 mg As kg<sup>- 1</sup>). The distribution of As in soils was related with particle size fraction and iron (Fe) oxide content. Total As increased markedly with decreasing particle size; sand ≪ silt < clay, with increasing As concentration generally correlated with increasing Fe concentrations (R<sup>2</sup> = 0.57). A sequential fractionation of soils collected from selected sites showed that As was primarily associated with the amorphous and crystalline Fe and Al oxide materials. Solid phase speciation of As-contaminated soil indicated that arsenate (As<sup>V</sup>) was the dominant As species present in the soil. However, in some soils, arsenite (As<sup>III</sup>) composed up to 40% of the total As present. The reasons for the presence of As<sup>III</sup> under alkaline and aerobic conditions are unclear. © 2005 Elsevier B.V. All rights reserved.
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