## 3 Results and Discussion
### Pot Experiments
juncea_ in Campana soil; on the contrary, the addition of FW to Nobile soil inhibits the process, as also highlighted by ANOVA and Tukey tests. Figure 4 reports translocation factors. These values indicate to what extent the elements absorbed by the plant are transferred to the aerial part or remain fixed in roots (higher values correspond to a greater transfer). P. vittata shows a very high TF for As in any soil at any treatment, even if this capability was much higher in soils without FW. However, this is the only exception because the other elements are retained in the roots. B. juncea has bioconcentration factors that are not particularly high; on the contrary, it shows good translocation factors, especially with respect to Cd in both soils. The ANOVA analysis (Table S5, Supplementary Materials) reveals a significant difference between the TF values of _P. vittata_ for As and the TF values of _B. juncea_ and _H. annuus_ for Cd and those of all the other plants. H. annuus and Z. mays exhibit a good translocation efficiency for the metals that were mainly absorbed, namely Zn, Cu, Cd and Ba. The use of the soil improver provokes an increase of translocation factors of _B. juncea_ towards Ba, Cd and Cr in the Nobile soil, whereas if we consider Campana soil the translocation of Cd and Ba in _B. juncea_ is enhanced when FW is not added to the soil. With respect to arsenic, the transfer to aerial parts of _P. vittata_ is more significant in the absence of the improver in both soils. Figure 4: Translocation factors (TFs) of plants chosen for phytoremediation and grown in (**a**) Campana without FW, (**b**) Campana with FW, (**c**) Nobile without FW and (**d**) Nobile with FW. Values are expressed as mean \(\pm\) SD. Despite these considerations, a plant is considered suitable for phytoextraction when it has TF and especially BF values greater than one, whereas when TF is less than one but BF is greater than one it can be a good candidate for phytostabilization [28]. _P. vittata_ shows values of BF greater than one for arsenic in both soils, for copper in the soil of the CA site and for cadmium for the CA soil in the presence of FW. Furthermore, it has TF \(\geq\) 1 for arsenic (in the CA soil without FW, it reaches a value of 17). _B. juncea_, on the other hand, has BF \(\geq\) 1 for Cd in NOB soils and shows TF \(\geq\) 1 for Cd in both soils (Tables S6 and S7, Supplementary Materials). In an attempt to estimate the feasibility of this treatment, the maximum percentage reductions for major anthropogenic contaminants were calculated for the most efficient plant, i.e., _P. vittata_. These values take into account the ratio between the amount of PTEs detected in the soil volume of each pot and the amount of metal present in the plant related to its total biomass. For the fern grown in the soil without FW, the maximum abatement percentages of 16%, 1.2%, 1.6%, 0.6% 0.7%, 3.5%, 0.8%, 1.2% and 2% were estimated for As, Ba, Cd, Co, Cr, Cu, Ni, Pb and Zn, respectively, whereas for the same elements the maximum abatement percentages of 4%, 1.3%, 3.5%, 0.9%, 1%, 3.2%, 1.3%, 1% and 1.8% were obtained for fern grown in the presence of the soil improver.