Heavy metal partitioning in soils profiles in the vicinity of an industrial complex and potential health implications

The industrial complex of Port Kembla, NSW, Australia comprises a Cu smelter, steelworks and associated industries. As part of an investigation into the regional extent in soils of a suite of metals, speciation in selected soil profiles was undertaken. A single aqua regia extraction and a six-step sequential extraction procedure were applied to soil samples at six different horizons to a depth of 50 cm from: (i) a contaminated, disturbed site located about 70 m from a major point source (C2); (ii) a contaminated undisturbed area situated 1.1 km from the contamination source (C1); and (iii) an uncontaminated, undisturbed area located 22.1 km from the complex (C3). In the uncontaminated soil profile, Pb was preferentially bound to hydrous Fe-Mn oxides and the less mobile fractions (crystalline Fe oxides, sulphides and organic matter). Lead partitioning was relatively constant with depth. In the contaminated undisturbed soil profile, the proportion of mobile Pb decreased with depth. Lead partitioning at the lower levels was similar to that of core C3. At the surface, Pb was preferentially bound to carbonates. In the contaminated disturbed soil profile, a large proportion of Pb was found in the labile forms to a depth of 40-50 cm. The contaminated disturbed site represents potential health and environmental hazards.