EDTA-Enhanced Phytoremediation of Lead-Contaminated Soil by Corn

ABSTRACT

EDTA-enhanced phytoremediation by corn (Zea mays L.) of soil supplemented with 500 mg L⁻¹ lead (Pb) was examined. The chelate EDTA was used in order to increase Pb bioavailability at four levels: 0 (control), 0.5 (low), 1.0 (medium), and 2.5 mmol kg⁻¹ (high). Plants were grown under controlled conditions in a growth-chamber with supplementary light. An EDTA concentration of 5.0 mmol kg⁻¹ was lethal to plants. At high and medium EDTA levels plants grew significantly less than control ones. Lead concentrations in corn leaves increased with increased EDTA levels. Plants subjected to medium EDTA level had the greatest root to shoot Pb translocation. Plants subjected to high EDTA level showed high phosphorus (P) uptake and translocation within plants. Therefore, possibly it was not only Pb that caused toxic effect on plants, but also the high internal concentration of P that in turn could have complexed active Fe.

Keywords:

• EDTA
• lead contamination
• heavy metals
• phytoextraction
• phytoremediation
• Zea mays

ACKNOWLEDGMENTS

The authors would like to thank Dr. P. Stewart for guidance; Dr. C. King for assistance with chemical preparation and analysis; and Dr. C. Vollrath for financial assistance.