Platinum and heavy metal concentration levels in urban soils of Naples (Italy)

Cd, Cu, Hg, Pb, Zn and Pt concentrations were determined in soil samples collected in the urban area of Naples (Italy). Particular attention has been posed on Pb and Pt content, due to their presence in vehicle emissions. The results evidence that Pb (mean 71, range 19-318 mg/kg) and Pt (mean 8.5, range <1-13.8 ng/g) concentrations are comparable with those found in other Italian urban soils. The concentrations of Zn, Cu, Cd and Hg are generally close to those of unpolluted soils. Higher heavy metal concentrations have been found in top soils and, in particular, the relatively high concentration levels of Pb suggest that the main pollution source could be related to vehicular emission. Zn, Cu, Pb, Cd and Hg are enriched in finer soil fraction, while Pt content does not show any relation with soil particle size. Data concerning Pt represent the first attempt to measure this element in urban soils of Naples and can be used as a reference level to evaluate a possible long-term accumulation trend following the introduction of the automobile catalytic converters.