Geochemical and isotopic study of soils and waters from an Italian contaminated site: Agro Aversano (Campania)

Lead isotope applications have been widely used in recent years in environmental studies conducted on different kinds of sampled media. In the present paper, Pb isotope ratios have been used to determine the sources of metal pollution in soils and waters in the Agro Aversano area.During three different sampling phases, a total of 113 surface soils (5–20 cm), 20 samples from 2 soil profiles (0–1 m), 11 stream waters and 4 groundwaters were collected. Major element concentrations in sampled media have been analyzed by the ICP-MS technique. Surface soils (20 samples), all soil profiles and all waters have been also analyzed for Pb isotope compositions by thermal ionization (TIMS). The geochemical data were assessed using statistic methods and cartographically elaborated in order to have a clear picture of the level of disturbance of the area. Pb isotopic data were studied to discriminate between anthropogenic and geologic sources.Our results show that As (5.6–25.6 mg/kg), Cu (9–677 mg/kg), Pb (22–193 mg/kg), Tl (0.53–3.62 mg/kg), V (26–142 mg/kg) and Zn (34–215 mg//kg) contents in analyzed soils, exceed the intervention limits fixed by the Italian Environmental Law for residential areas in some of the sampled sites, while intervention limit for industrial areas is exceeded only for Cu concentrations. Lead isotopic data, show that there is a high similarity between the ratios measured in the leached soil samples and those deriving from anthropic activities. This similarity with anthropogenic Pb is also evident in the ratios measured in both groundwater and stream water samples.

Research highlights
► Pb isotope ratios have been used to determine sources of metal pollution in the Agro Aversano area.
► Pb isotopic composition in soils and waters helped to discriminate between anthropogenic and geologic sources.
► In some areas of the Agro Aversano territory As, Cu, Tl and Zn exceed intervention limits for a residential use of soils.