Biomonitoring of atmospheric deposition of potentially toxic elements at rural sites in Tuscany (Central Italy)

This study investigated the accumulation (deposition) of 13 potentially toxic elements (PTEs) in moss tissue (dominated by Hypnum cupressiforme at 64% and Pseudoscleropodium purum at 13.4%) collected from 33 rural sites of Tuscany (Central Italy). In addition, the magnetic susceptibility of moss was measured to provide insight into the accumulation of anthropogenic particles. Prior to the analysis, moss samples were washed, and the rinse waters were also analyzed for PTEs. Exploratory spatial analysis and source identification of airborne PTEs were carried out; the results suggest that the main anthropogenic airborne pollutants in the region were Cd and Zn from long-range transport with the mean concentrations of 0.12 mg/kg and 18.2 mg/kg, respectively. Wet deposition was the dominant source for these elements, which were however accumulated by moss in modest amounts. Soil also emerged as an important source for several elements i.e., Al, Fe, Cr and Ni, but its contribution was largely unpredictable, as indicated by the lack of correlation between moss tissue and rinse water concentrations. Further, sample washing of a few seconds was not effective in fully removing soil particles. The sensitivity analysis suggested that the results of the study are reliable and did not depend on the methodology used for data analysis. This is the first comprehensive regional-scale study in rural areas of Tuscany using moss biomonitoring, and as such, it provides important baseline data for future research.