## 3 Results and Discussion
### Atmospheric Deposition  
#### 3.2.1 Annual Deposition Rates  
The atmospheric deposition investigation was carried out on four locations taking into account the characteristics of the territory under study. Each sampling system consists of two deposimeters (1 for organic fraction and 1 for inorganic) to carry out the analytical determinations of organic and inorganic chemical contaminants in the airborne particle deposition. The analysis was performed for determining organic, i.e., PCDD/Fs, DL-PCBs and PAHs, and inorganic-metal, i.e., As Ba Be Cd Co, total Cr, Cu, Mn, Ni, Pb, Sb, Se, Sn, Sr, Te, Ti, Tl, V, Zn, micro-pollutants. Table 1 summarizes the main regulation developed by various European countries [32] both on atmospheric deposition rate and on the content of PCDD/Fs + DL-PCBs and on some metals. Table S2 of the Supplementary Material shows the measurements of the deposition rate of the total sedimentable dusts for each location and season. This measure is an important indicator of particular local environmental conditions, such as fouling, deposit on crops and soil, with possible exposure of the population by ingestion, etc., which is given increasing attention. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multicolumn{1}{c}{**Dust 1**} & \multicolumn{1}{c}{**As 2**} & \multicolumn{1}{c}{**Cd 2**} & \multicolumn{1}{c}{**Hg 2**} & \multicolumn{1}{c}{**Ni 2**} & \multicolumn{1}{c}{**Pb 2**} & \multicolumn{1}{c}{**Tl 2**} & \multicolumn{1}{c}{**Zn 2**} & \multicolumn{1}{c}{**PCDD/Fs + DL-PCBs**} \\ \cline{5-12} \multicolumn{1}{c}{} & \multicolumn{1}{c}{} & & & & & & & **Monthly 3** & **Annual 3** \\ \hline Austria & 210 & – & 2 & – & – & 100 & – & – & - & - \\ Belgium & 350 & – & 2 & – & – & 250 & – & 21 & 8.2 \\ Croatia & 350 & 4 & 2 & 1 & 15 & 100 & 2 & – & 4 \\ Germany & 350 & 4 & 2 & 1 & 15 & 100 & 2 & – & - & 4 \\ UK & 200 & – & – & – & – & – & – & – & - & - \\ Switzerland & 200 & – & 2 & – & – & 100 & 2 & 400 & - & - \\ Slovenia & 200 & – & 2 & – & – & 100 & – & 400 & - & - \\ \hline \hline \end{tabular}  
* Expressed as mg m\({}^{-2}\)d\({}^{-1}\); 2 as ug m\({}^{-2}\)d\({}^{-1}\); 3 pg WHO-TE\({}_{1998}\) m\({}^{-2}\)d\({}^{-1}\).  
\end{table} 
Table 1: Reference values of deposition rates for dust, some metals and PCDD/Fs + DLPCBs in some European legislations [32]. Figure 3: Distribution of wind speeds for each wind sector. European and national legislation does not indicate limit values for the deposition rate of sedimentable dusts. Consequently, an assessment of the extent of the phenomenon can be obtained by comparison with reference values or limits suggested in guidelines or in legislative acts of other European countries (Table 1) [32]. The deposition rates based on monthly collecting period, measured at the Allumiere, S. Agostino, Roccaccia and Rocca Respampani stations, vary between 8.1 mg m\({}^{-2}\) d\({}^{-1}\) recorded in the autumn 2015 season at the Roccaccia station, to the 49.3 mg m\({}^{-2}\) d\({}^{-1}\) recorded in the spring 2016 season again in Roccaccia (Table S1 of the Supplementary Material). On the other hand, the deposition rates based on annual collecting period measured in the entire period in the four stations, are, respectively, reported in Table 2.  
The analysis of these data shows that the stations do not show areas with high rates of atmospheric deposition of total sedimentable dusts, compared to what is reported both in the legislation of different countries and in the scientific literature. Autumn has the lowest dustiness in all locations, while the Allumiere location, also the winter season, is associated with low dustiness. Spring appears to be the season with the highest dustiness in all locations. In fact, a seasonal variability can be observed that sees the atmospheric depositions of total sedimentable dusts increase, when passing from the humid season to the drier one. This trend can be explained by the greater contribution to the total depositions brought about by the rising phenomena of the total sedimentable dusts from the ground.