## 4 Conclusions  
Two Turin sites, exploitable as urban gardens, were compared for PTE content. The urban soil located in the city center, the CA site, was found contaminated by Pb, Ba and Zn and, to a lower degree, by As, Cu and Cd, due to exposure to urban pollution. The study on the phytoextraction efficiency of four plant species cultivated in controlled conditions in both soils highlighted a great ability of _P. vittata_ to abate As, even if it was not one of the major pollutants. Considering this kind of fern, it is possible to assume that, in the adopted experimental conditions, a 15% reduction of As after a life cycle could be obtained, whereas four vegetative cycles would be necessary to achieve the same result for Cu and, for Pb, the treatment must be further prolonged. _B. juncea_ is promising for the bioconcentration and translocation of cadmium, whereas _H. annuus_ showed interesting TF values for Zn, Cd and Ba. _Z. mays_, on the contrary, did not demonstrate high performances in the examined experimental conditions. The effect of the addition of a soil improver supplied by Acea Pinerolese is controversial. In the case of _B. juncea_, it seems to favor the absorption of PTEs by carrying out a positive activity on the growth of the plant and on the development of the root system. Moreover, it inhibits PTE extraction by _P. vittata_ and _Z. mays_ competing with them by the complex and withholding of the PTEs, whereas the influence on _H. annuus_ is negligible. Therefore, its use must be assessed according to individual cases and the desired effect. **Supplementary Materials:** The following are available online at [[http://www.mdpi.com/2076-3417/10/11/3948/s1](http://www.mdpi.com/2076-3417/10/11/3948/s1)]([http://www.mdpi.com/2076-3417/10/11/3948/s1](http://www.mdpi.com/2076-3417/10/11/3948/s1)), Table S1: Summary of multiple pairwise comparisons on element concentrations in soils obtained with ANOVA and Tukey tests. B identifies soil samples whose mean concentrations in the respective elements are significantly lower than the ones obtained for soil samples identified by A; the same concept applies to C with respect to B and D with respect to C, Table S2: Element concentration (mg/kg) \(\pm\) SD in the plants' aerial parts. NOB = plants grown in Nobile soil, CA = plants grown in Campana soil, FW = addition of amendment to the soil, _p = Pteris vittata_, _b = Brassica juncea_, _h = Heliumthus annuus_, _z = Zea mays_, Table S3: Element concentration (mg/kg) \(\pm\) SD in the plants' roots. NOB = plants grown in Nobile soil, CA = plants grown in Campana soil, FW = addition of amendment to the soil, _p = Pteris vittata_, _b = Brassica juncea_, _h = Heliumthus annuus_, _z = Zea mays_, Table S4: Summary of multiple comparisons for pairs of the plants' BF with Tukey test. NOB = plants grown in Nobile soil, CA = plants grown in Campana soil, FW = addition of amendment to the soil, _p = Pteris vittata_, _b = Brassica juncea_, _h = Heliumthus annuus_, _z = Zea mays_. B identifies BF values whose means are significantly lower than the ones obtained for BF values identified by A; the same concept applies to C with respect to E, B with respect to F and G with respect to F, Table S6:Bioconcentration factors (BFs) \(\pm\) SD. Values \(>1\) are reported in bold, Table S7: Translocation factors (TFs) \(\pm\) SD. Values \(>1\) are reported in bold. **Author Contributions:** Conceptualization, A.F. and P.C. ; methodology, A.F. and M.M. ([PERSON]); formal analysis, E.G. ; investigation, D.F. and G.B. ; resources, M.M. ([PERSON]), D.F. and A.F. ; data curation, G.B. ; writing--original draft preparation, E.G. and M.M. ([PERSON]); writing--review and editing, D.F., M.M. ([PERSON]) and P.I. ; visualization, E.G. ; supervision, M.M. ([PERSON]), A.F. and P.C. ; project administration, M.M. ([PERSON]) and P.C. ; funding acquisition, P.C. All authors have read and agreed to the published version of the manuscript. **Funding:** This work received funding from Compagnia di San Paolo (project CSTO168877-ReHortici).