Phytoremediation of lead-contaminated soils using Zea mays (L.)

We investigated the ability of the corn plant in the clean-up of lead-contaminated soils using EDTA as a chelating agent under outdoor conditions for a period of eight weeks. Corn seeds were planted on June 3 in 6" x 5" plastic pots (1.5 lb) containing soil medium (planting mix:delta top soil in 2:1 v:v). Each pot was placed in a separate plastic tray to avoid cross contamination. Experimental units were arranged in a 3 Pb (lead) x 3 EDTA [(ethylenedinitrilo)-tetraacetic acid] factors in randomized complete blocks (RCB) design with 4 replications. Lead and EDTA were added to the soil medium 5 weeks after initial planting and 3 weeks prior to harvesting. Results indicated that Pb and EDTA treatments do not have any significant effect on the growth of the corn plant. The highest concentration of chlorophyll was encountered at 1000 ppm Pb (0.24 +/- 0.03 mug/mg dry weight) followed by 2000 ppm Pb and 10 mM EDTA (0.18 +/- 0.03 mug/mg dry weight). Lead concentrations in shoot tissues showed maximum values in plants treated with 1000 ppm Pb at all EDTA amendments (139 +/- 49 ppm at 5 mM EDTA to 310 +/- 128 ppm at 10 mM EDTA). Root tissues showed consistently greater values of Pb than in the shoot tissues at all EDTA amendments.