Potentially harmful elements and lead isotopes distribution in a heavily anthropized suburban area: the Casoria case study (Italy)

This study presents the results of 12 trace elements that have been classified by Italian Environmental law as potentially dangerous to human health and new Pb isotope data for topsoils and soil profiles collected in the Casoria municipal area (Napoli). Elemental concentrations were determined in 126 topsoil samples and were produced interpolated distribution (MIDW) and baseline maps using GeoDAS software. Results show Casoria soils to be significantly enriched in several elements (e.g., Cd, Cu, Pb, Zn). Two geochemical sources were determined associating elemental distribution with the background values of Neapolitan soils: one geogenic and another one anthropogenic. High As, Co, Se and Tl concentrations are coherent with bedrock lithology, and elemental concentrations show the same values typical of Neapolitan volcanic soils. Higher Cd, Hg, Pb and Zn concentrations can be linked with anthropic activities coherent with previous studies in the Neapolitan area. Cr, Cu, Sb and V geochemical concentration and distribution shows both geogenic and anthropogenic influence. Pb isotope analyses allow the determination of the source of the Pb and the level of anthropogenic/geogenic influence on their concentration. Pb sources in the Casoria soils overlap the isotopic compositions typical of industrial soils/aerosols. This anthropic influence on Pb concentration is quantified by anthropogenic fraction (AF%). Casoria topsoil shows very high amount of anthropogenic Pb: AF% is 41–58 %. In profile soil samples leached (L) AF(%) is 31–43 % (topsoils) and 38–56 % (bottom soils); in profile soil samples residues (R) AF(%) is shifted toward the geologic signature, 18–43 % (topsoils) and 25–50 % (bottom soils).