Atmospheric deposition of potentially toxic elements in a peri-urban industrial landscape: Evaluating legacy vs. current pollution

This study investigated the atmospheric deposition of 13 potentially toxic elements (PTEs; As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Sn, Tl, V, Zn) in the historically industrialised Scarlino Plain, Tuscany (Italy). Monthly bulk deposition was monitored over one year at three strategically selected sites, revealing marked spatial and temporal variability, with Zn and Mn dominating flux profiles. Comparison with reference values suggests moderate contamination characteristics of peri-urban contexts, yet lower than levels reported for heavily industrialised areas. Multivariate analysis linked PTE deposition patterns to both geogenic and anthropogenic sources, including legacy pyrite roasting, current industrial activity and vehicular emissions. While major elements showed relatively uniform behaviour across sites, minor elements (Sb, Sn, Co, and Pb) exhibited site-specific peaks, likely reflecting episodic local anthropogenic contributions. The differences among the sites were further modulated by wet and dry deposition dynamics under local meteorological conditions. Based on the calculated soil-to-deposition (S/D) ratios, current atmospheric inputs exert minimal influence on soil PTE concentrations, which are primarily driven by historical contamination. This is particularly evident for As, Mn, and Co, where present-day deposition constitutes only a small fraction of the legacy loads. Despite declining emissions, legacy pollution continues to influence both soil and atmospheric PTE dynamics via particle resuspension, highlighting the need for targeted remediation and long-term monitoring. These findings refine our understanding of PTE cycling in peri-urban settings and support integrated management strategies in areas impacted by past and ongoing emissions.