Bioaccessibility of metals in soils surrounding two dismissed mining sites in Northern Italy

Mining activities are one of the main contributors to metals contamination of soils, most often due to the inappropriate management of the mining residues. In Italy, hundreds of small mining sites are scattered around the mountainous areas, near small villages with fragile environments. Here, wastes and residues may have polluted the surrounding soils and become a threat to living organisms. We investigated two dismissed sites in Northern Italy with extractive wastes in unmanaged areas close to villages using bioaccessibility and size fractionation methods, focussing on particles that can potentially be eroded and/or ingested (<10 µm and<200 µm). In the Campello Monti site, Co, Cu and Ni showed high values in soils near the landflls, with the highest concentrations in the<10 µm particles around the landflls and along the valley bottom. Lead and Ni were the most bioaccessible metals. In the Plassa site, Cd and Zn were the most important contaminants, with an average content of 118 and 34,000 mg/kg. They originated from mining wastes scattered through the slope and had a particularly high bioaccessible fractions, close to the 100% for Zn and above 80% for Cd in the fne particles. The study of the fne, more reactive and mobile particles ofered a close insight into the lability of contaminants, as in both sites, a dispersion of metal contaminants through very fne particles in surrounding and downhill areas was observed, resulting in an increased risk to all living organism and for the environment.