## 3 Results and Discussion
### Soil Characterization
The presence of barium, usually used in paints and glass [41], can also be traced back to the history of this site, which, according to our information, has been a public garden for decades, but is located in an area of Turin that underwent several bombings during the Second World War, with the consequent accumulation of debris. Table 3 reports the concentrations of the elements determined in the soil added with a soil improver before filling the pots for plant cultivation in the growth chamber. The composition of FW is also reported. FW has low concentrations of most PTEs, while it is rich in macronutrients such as P, Ca, Mg and K and in micronutrients such as Na, Zn and Cu. The high load of some elements present in FW, e.g., P, Na, K and Ca, determines an increased amount of these elements in the soils added with the improver. The concentration of Zn in FW is very high; however, the addition of the improver in a percentage of 30% does not alter the concentration of Zn, whereas it causes a slight increase in the NOB soil. Considering the variability of analytical data for soil and FW element concentration, we can assess that the addition of FW does not significantly affect the content of most of the examined elements. The Tukey test with a level of confidence of 95% was used for multiple pairwise comparison after the ANOVA test in order to check if the analytes' concentrations determined in the CA and NOB samples without and with improver addition were significantly different (Table S1, Supplementary Materials). Cu, Pb, Ba and Zn have statistically different concentrations in the two sites, regardless of the addition of FW. No significant difference was found for the concentration of Al, Ca, Ce, Cr, Fe, La, Mg, Mn, Na, Ni, Ti and V, so the probable geogenic origin of Cr and Ni is confirmed. The different concentration of P in each soil highlights its different amount in the pristine soils and the influence of FW on its concentration. K concentration differs mainly according to the addition of the soil improver, whereas for As, Cd and Co the differentiation derives from the combination of soil type and addition of FW. \begin{table}
\begin{tabular}{l r r r r r r r} \hline \hline  & \multicolumn{3}{c}{**NOB t\({}_{0}\)**} & \multicolumn{3}{c}{**CA t\({}_{0}\)**} & \multicolumn{3}{c}{**Public Green Area Limit**} & \multicolumn{1}{c}{**Industrial Area Limit**} \\ \hline Al & 22,298 & \(\pm\) & 3280 & 23,184 & \(\pm\) & 1140 & & & \\ As & 9.33 & \(\pm\) & 0.70 & 15.8 & \(\pm\) & 1.7 & 20 & & 50 \\ Ba & 104 & \(\pm\) & 15 & 322 & \(\pm\) & 48 & & & \\ Ca & 11,487 & \(\pm\) & 1493 & 21,412 & \(\pm\) & 8483 & & & \\ Cd & 0.21 & \(\pm\) & 0.03 & 1.16 & \(\pm\) & 0.09 & 2 & & 15 \\ Ce & 42.4 & \(\pm\) & 0.3 & 36.5 & \(\pm\) & 3.6 & & & \\ Co & 23.2 & \(\pm\) & 1.5 & 16.6 & \(\pm\) & 1.8 & 20 & & 250 \\ Cr & 248 & \(\pm\) & 37 & 150 & \(\pm\) & 74 & 150 & & 800 \\ Cu & 39.5 & \(\pm\) & 3.3 & 75.2 & \(\pm\) & 3.8 & 120 & & 600 \\ Fe & 33,552 & \(\pm\) & 2204 & 32,312 & \(\pm\) & 2960 & & & \\ K & 4969 & \(\pm\) & 1207 & 3867 & \(\pm\) & 126 & & & \\ La & 18.8 & \(\pm\) & 0.3 & 19.7 & \(\pm\) & 5.6 & & & \\ Mg & 22,819 & \(\pm\) & 3971 & 16,458 & \(\pm\) & 5670 & & & \\ Mn & 870 & \(\pm\) & 13 & 958 & \(\pm\) & 136 & & & \\ Na & 330 & \(\pm\) & 138 & 445 & \(\pm\) & 17 & & & \\ Ni & 253 & \(\pm\) & 29 & 147 & \(\pm\) & 22 & 120 & & 500 \\ P & 617 & \(\pm\) & 29 & 1169 & \(\pm\) & 79 & & & \\ Pb & 34.3 & \(\pm\) & 0.6 & 312 & \(\pm\) & 44 & 100 & & 1000 \\ Sr & 33.1 & \(\pm\) & 2.7 & 49.4 & \(\pm\) & 20.8 & & & \\ Ti & 865 & \(\pm\) & 108 & 795 & \(\pm\) & 83 & & & \\ V & 43.5 & \(\pm\) & 5.0 & 46.1 & \(\pm\) & 3.1 & 90 & & 250 \\ Zn & 96.7 & \(\pm\) & 7.4 & 221 & \(\pm\) & 21 & 150 & & 1500 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Element concentration (mg/kg) \(\pm\) standard deviation (SD) in NOB and CA sites and Italian legislation limits.