## 4 Results
### Site 2  
The radon activity concentrations in the groundwater extracted from site 2 wells in the period 2021-2022 are reported in Table 3. Tables 4 and 5 contain the groundwater levels and contents of NAPLs (total hydrocarbons, MTBE and ETBE), respectively. Radon concentrations ranged between 0.1 Bq L\({}^{-1}\) (well PZ06 in February 2022) to 53 Bq L\({}^{-1}\) (well SN03 in November 2021) (Figure 3). Two areas with average lower radon levels were recognized around wells PZ05 and PZ02 (2.2 Bq L\({}^{-1}\)) and nearby wells PZ04, PZ06, PZ07, and PZ08 (1.6 Bq L\({}^{-1}\)). On the other hand, higher average radon (12.4 Bq L\({}^{-1}\)) was detected in wells located away from the contamination (wells PZ01, PZ09, SN1, SN3, and SN9). \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline  & & **May 2021** & **October 2021** & & **December 2021** & \\ \hline \multirow{2}{*}{VEP} & Depth & \({}^{222}\)Rn & \({}^{222}\)Rn & \({}^{222}\)Rn & CH\({}_{4}\) & VOCs \\  & m & Bq m\({}^{-3}\) & Bq m\({}^{-3}\) & Bq m\({}^{-3}\) & ppm & ppm \\ \hline \multirow{4}{*}{VEP01} & 0–5 & nm & nm & nm & 0 & 0.4 \\  & 6–10 & nm & nm & nm & 0 & 151 \\  & 11–14 & nm & nm & 1100 & 60,000 & 615 \\  & 15–18 & nm & nm & 175,000 & 0 & 26 \\ \hline \multirow{4}{*}{VEP04} & 0–5 & 56,000 & 70,000 & nm & nm & nm \\  & 6–10 & nm & nm & nm & nm & nm \\ \cline{1-1}  & 11–14 & nm & nm & nm & nm & nm \\ \cline{1-1}  & 15–18 & 127,000 & 113,000 & nm & nm & nm \\ \hline \hline \end{tabular} nm stans for not measured.  
\end{table} 
Table 2: Radon, methane, and VOC concentration in soil gas from two vapor extraction wells (VEP) in site 1. \begin{table}
\begin{tabular}{l c c c c c c} \hline \hline
**Wells** & **222**Rn (Bq L\({}^{-1}\))** & **222**Rn (Bq L\({}^{-1}\))** & **222**Rn (Bq L\({}^{-1}\))** & **222**Rn (Bq L\({}^{-1}\))** & **222**Rn (Bq L\({}^{-1}\))** \\ \hline  & **May 2021** & **September 2021** & **November 2021** & **February 2022** & **May 2022** & **September 2022** \\ \hline SN01 & 10.1 \(\pm\) 0.8 & 31.6 \(\pm\) 2.2 & 25.1 \(\pm\) 2.2 & 17.1 \(\pm\) 1.3 & - & - \\ PZ08 & 2.1 \(\pm\) 0.3 & 2.4 \(\pm\) 0.4 & 2.0 \(\pm\) 1.6 & 1.9 \(\pm\) 0.3 & 2.4 \(\pm\) 0.4 & 1.6 \(\pm\) 0.3 \\ PZ09 & 10.4 \(\pm\) 0.9 & 1.9 \(\pm\) 0.3 & 5.1 \(\pm\) 1.6 & 14.6 \(\pm\) 1.2 & 4.3 \(\pm\) 0.5 & 6.1 \(\pm\) 0.6 \\ SN09 & 22.5 \(\pm\) 1.9 & 22.8 \(\pm\) 1.7 & 30.9 \(\pm\) 2.3 & 23.6 \(\pm\) 1.7 & - & - \\ SN03 & 47.1 \(\pm\) 3.1 & 44.3 \(\pm\) 3.0 & 53 \(\pm\) 3.4 & 40.5 \(\pm\) 2.7 & - & - \\ PZ03 & 8.2 \(\pm\) 0.8 & 31.2 \(\pm\) 2.3 & 22.1 \(\pm\) 1.9 & 13.4 \(\pm\) 1.1 & 8.3 \(\pm\) 0.8 & 9.6 \(\pm\) 0.8 \\ PZ05 & 2.6 \(\pm\) 0.4 & 6.5 \(\pm\) 0.6 & 3.3 \(\pm\) 1.3 & 1.7 \(\pm\) 0.3 & 1.6 \(\pm\) 0.3 & 1.9 \(\pm\) 0.3 \\ PZ04 & 1.4 \(\pm\) 0.3 & 4.9 \(\pm\) 0.5 & 2.4 \(\pm\) 1.5 & 1.8 \(\pm\) 0.3 & 10.3 \(\pm\) 0.9 & 0.8 \(\pm\) 0.2 \\ PZ07 & 0.8 \(\pm\) 0.2 & 1.5 \(\pm\) 0.3 & 0.3 \(\pm\) 1.5 & 1.3 \(\pm\) 0.3 & 1.5 \(\pm\) 0.3 & 1.1 \(\pm\) 0.2 \\ PZ02 & 0.9 \(\pm\) 0.2 & 0.4 \(\pm\) 0.2 & - & 0.3 \(\pm\) 0.1 & 1.1 \(\pm\) 0.2 & 1.0 \(\pm\) 0.2 \\ PZ06 & 0.8 \(\pm\) 0.2 & 0.7 \(\pm\) 0.2 & 0.6 \(\pm\) 1.6 & 0.1 \(\pm\) 0.1 & 1.4 \(\pm\) 0.3 & 0.3 \(\pm\) 0.1 \\ PZ01 & 1.0 \(\pm\) 0.2 & 3.0 \(\pm\) 0.4 & 13.6 \(\pm\) 1.7 & 1.2 \(\pm\) 0.2 & 10.9 \(\pm\) 0.9 & 16.4 \(\pm\) 1.2 \\ SN01 & 10.1 \(\pm\) 0.8 & 31.62.2 & 25.1 \(\pm\) 2.2 & 17.1 \(\pm\) 1.3 & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Radon activity concentrations in the 12 monitoring wells of site 2 in the period 2021–2022. According to the radon deficit principle, wells PZ02 and PZ05 with low radon were characterized by the presence of total hydrocarbons (up to 26,000 ug L\({}^{-1}\)) and to a lesser extent MTBE (up to 63 ug L\({}^{-1}\)), whereas well PZ06 was affected only by moderate levels of MTBE (up to 54 ug L\({}^{-1}\)). Finally, ETBE was always significantly found in well SN03 (up to 88 ug L\({}^{-1}\)).