Possibility for using of two Paulownia lines as a tool for remediation of heavy metal contaminated soil

One-year-old two Paulownia lines (P.tomentosa x fortunei - TF 01 and P. elongata x fortunei EF 02) were grown, as pot experiment, in soil collected from the field of waste depository of Kremikovtzi ferrous metallurgical industry near Sofia. The soil was heavily polluted with Cd. Metals content (Ca, Mg, K, Na, Cd, Cu, Pb, Zn and Fe) in soil and its distribution in roots, stems and leaves of both lines was studied. The results showed that Ca and K accumulated more in stem, Mg, Na, Fe and Cd in root, while Pb, Cu and Zn in the leaves of both lines. The bioaccumulation factor (BF) and translocation factor (TF) were evaluated in order to determine the potential of plants in removing metals from contaminated soil. The BF for Fe, Pb, Cu and Zn in TF 01 line exceeded that of EF 02 line - 5.6; 1.03; 1.20; 1.14 times, respectively. TF was higher in TF 01 line for Fe, Pb and Cd (6.0; 1.92 and 1.03, respectively), but not for Cu and Zn. The success of phytoremediation depends on plant groWth and restricted distribution of heavy metals in shoots. Our results showed that stem length and total leaf area of Paulownia elongata x fortunei were higher than Paulownia tomentosa x fortunei but BF for Cu and Zn and TF for Pb was less. BF for Cd was 1.7 times higher and TF for Zn was 1.03 times higher in Paulownia elongata x fortunei. Selected two lines (P. tomentosa x fortunei TF 01 and P elongata x fortunei EF 02) were accumulators of Cu, Zn and Cd. Paulowniatomentosax fortunei accumulated more Pb and Zn in aboveground parts, while Paulownia elongata x fortunei accumulated Zn only. These lines proved to be a promising species for phytoremediation of heavy metal polluted soils due to high biomass productivity.