Lead Phytoextraction from Soil by Corn, Sunflower, and Cotton Applying EDTA and Sulfuric Acid

The contamination of soils with lead is a major environmental problem throughout the world. Phytoextraction of heavy metals from contaminated soils has the prospect of being a more economic in situ alternative. Chemically enhanced phytoextraction has been proposed as an effective approach to remove heavy metals from contaminated soil through the use of high biomass plants. Using a pot experiment, the effects of the application of three rates of EDTA at 0, 1.5 and 3 mmol/kg soil and sulfuric acid at 0, 0.5 and 1 mmol/kg soil with two rates of Pb at 0 and 200 mmol.kg-1 on the uptake of Pb by corn (Zea mays L. single cross 704 var.), sunflower (Helianthus annuus L. ajili var.), and cotton (Gossypium hirsutum L. varamin var.) plants were studied. The results showed that EDTA was more effective than sulfuric acid in increasing the concentration of Pb in shoots and roots for all plants studied. The maximum amount with application of EDTA to soil for shoots of corn, sunflower, and cotton were 4.07, 6.49 and 31.33 times higher than the control, respectively. EDTA also enhanced Pb content of roots of corn, sunflower, and cotton 3.38, 1.63 and 1.09 times higher than the control, respectively. DTPA-Pb was higher in soil treated with EDTA than sulfuric acid. The application of EDTA also significantly increased shoot-to-root ratio of Pb in plants examined. The results of this study showed that corn was able to phytoextract more Pb than sunflower and cotton.