# New Light on Phtyoremediation: The Use of Luminescent Solar Concentrators
## 3 Results
### Second Phase: Outdoor Comparison between LSC and Polycarbonate Boxes
A similar increase was also found in the aerial part of the sunflower, with an increase in the concentration of Pb of about 4.5 times in plants grown under the polycarbonate box and about 6 times in those grown under the red box. The most relevant effects of the addition of EDTA were found in the lupine plants with increases in Pb concentration of the aerial part of about 10 times the value found in the plants not treated with the chelating agent. The results were the same for both boxes. The effect of EDTA was instead not very evident in the root system, where the difference in the concentration of Pb between treated and untreated microcosms was always minimal. Lead is not easily transferred to above-ground plant biomass, since it is mainly stored in root cells [50; 51]. In this experiment, the addition of EDTA has proved to be particularly  
Figure 10: A picture of plants grown under the two different boxes, (**a**) _L. albus_, (**b**) _H. annuus_, and (**c**) _B. juncea_. On the left of the beholder, the plants grown under the LSC box. effective for phytoextraction because it seems to have favored the translocation of the metal in the aerial part. It can be supposed that EDTA chelates Pb in the soil liquid phase then the soluble Pb-EDTA complex enters the roots and Pb is transported through the plant and accumulated in the aerial part [52]. The results did not show any adverse effect of EDTA on arsenic uptake. This can be ascribed to the action that EDTA carries out on iron oxides, partially solubilized by the complexing agent [53]. The mobility of arsenic in soil is greatly influenced by the presence of Fe-oxides where significant amounts of As are adsorbed [54]. Arsenate forms outer-sphere complexes by electrostatic coulombic interactions on all variable charge minerals [54]. It can be hypothesized that the disruptive effects of the oxides by EDTA release the arsenic that goes into soil solution becoming available for plants. As a matter of fact, in the specific contaminated soil, the plants can uptake both the contaminants even if not essential elements. There were no differences in the concentration of the two metals between the plants grown in the polycarbonate box and the LSC red box. After all, the EDTA metal complexes are poorly photodegradable in the soil, mostly when plants have grown and in the alkaline conditions of soil pH [55]. The total accumulation of the two metals for the three investigated plants is reported in Figure 11 for As and Pb. This parameter, which, as previously stated, is essential in evaluating the efficiency of phytoremediation, shows a positive effect of the LSC panels, as it is generally higher for tests carried out in the red box. The results showed that plants development under the red box also appears visually higher than that under the polycarbonate box. Thus, the positive effects are more explicit in outdoor tests rather than in greenhouses, as in general the light conditions in the greenhouse tend to decrease due to the shielding effect of the walls of the structure. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & \multicolumn{6}{c}{**Aerial Part**} & \multicolumn{6}{c}{**Roots**} \\ \hline  & \multicolumn{3}{c}{**As**} & \multicolumn{3}{c}{**Pb**} & \multicolumn{3}{c}{**As**} & \multicolumn{3}{c}{**Pb**} \\  & **Mean** & **SD** & **Diff. \%** & **Mean** & **SD** & **Diff. \%** & **Mean** & **SD** & **Diff. \%** & **Mean** & **SD** & **Diff. \%** \\ \hline B & 42.2 & 1.6 & — & 4.7 & 0.4 & — & 2181 & 82.1 & — & 178 & 9.6 & — \\ B LSC & 45.2 & 4.2 & +7.2 & 4.3 & 0.5 & \(-\)7.8 & 2238