Phytoremediation of lead-contaminated soils using Mirabilis jalapa (L.)

Research investigations were conducted to assess the ability of Mirabilis jalapa as a phytoremediator of lead contaminated soils as a substitute technology for traditional methods. Mirabilis plant seeds were planted on June 3 in 6"x 5" plastic pots (1.5 lb) containing soil medium (planting mix:delta top soil 2:1 v:v). Each pot was placed in a separate plastic tray to avoid cross contamination. Experimental units were arranged in a 3 lead (Pb) x 3 EDTA [(ethylenedinitrilo)-tetraacetic acid] factors with 4 replications. Lead and EDTA were added to soil medium 5 weeks after initial planting and 3 weeks prior to harvesting. The total chlorophyll was found to be slightly higher in the control treatment (1.07 +/- 0.51 mug/mg dry weight) as compared to the 2000 ppm Pb treatment (0.54 +/- 0.07 mug/mg dry weight). Lead concentrations in the shoots increased as the EDTA concentrations increased indicating the chelating agent has a positive impact on absorption and translocation of lead into shoots (1357 +/- 526 ppm Pb at 2000 Pb/0 mMEDTA treatment vs 3192 +/- 637 ppm Pb at 2000 Pb/10 mM EDTA treatment) from the root tissues. We found an inverse relation between shoot Pb versus root and remaining Pb in soil medium. This implies that lead was effectively transported from the soil and roots into the shoots.