Evaluation of the bioavailability of potentially harmful elements in urban soils through ammonium acetate-EDTA extraction: a case study in southern Italy

Bioavailability of some harmful elements in the urban soils of the cities of Avellino, Benevento, Caserta, Napoli and Salerno (Italy) has been evaluated through an analytical process based on an ammonium acetate-EDTA extraction followed by ICP-MS analysis. Comparison between concentration values obtained for the same samples by means of an aqua regia leach and a weaker extraction such as ammonium acetate-EDTA (AA-EDTA) demonstrates how some elements, mostly of anthropogenic origin in the study areas (e.g. Cd, Cu, Pb, Zn), are more easily available to the biological cycle and thus more harmful to human health than others of strictly geogenic origin (e.g. As, Tl and V), depending on their chemical binding in the crystalline lattice of the soil minerals. Determination of elemental bioavailability can help to evaluate the environmental risks of human exposure and to redefine the local intervention levels for risk assessment based on a better knowledge of the geochemical background concentrations.