Effect of chelating agent on phytoextraction of lead from contaminated soil by Zea mays

摘要

Phytoextraction of heavy metals enhanced by using chelating agents was proposed as an effective approach to remove heavy metals from contaminated soil by use of hyper accumulator plants. The effects of application of chelating agents viz., Cyclohexane diamino tetraacetic acid (CDTA), Citric acid (CA), Diethylene triamine pentaacetic acid (DTPA), Nitrilo triacetic acid (NTA) @ 10 mmol kg(-1) soil and FYM (at 3%) on the growth of Zea mays and its Pb uptake were investigated in sewage sludge un-amended and amended (at 3%) soil using the pot-culture experiments. Application of chelating agents decreased the dry matter yield of roots of Zea mays while, higher values of dry matter yield (8.86 g pot(-1)) was observed in case of FYM sewage sludge amended soil at 80 days after sowing. FYM addition was found beneficial as compared to control (Pb-180). Dry matter yield of shoots of Zea mays increased over control due to application of CDTA and FYM. The highest dry matter yield of shoot (63.29 g pot(-1)) was observed in CDTA with sewage sludge amended soil at 80 days after sowing. Whereas reverse trend was observed in NTA, CA and DTPA treated soils. Addition of sewage sludge at 3% on dry weight basis was found beneficial in improving the plant growth. Chelating agents enhanced. the Pb uptake by both roots and shoots. The higher values of Pb uptake by roots (2.89 mg pot(-1)) and shoots (13.21 mg pot(-1)) was observed in CDTA treated soil after 80 days of sowing in sewage sludge amended soil as compared to un-amended soil. Application of CDTA was found more effective in enhancing the Pb uptake by Zea mays roots and shoots than any other chelating agents at both the growth stages. Concentration of Pb in root was higher than that of shoots. Maximum Pb concentration was observed in NTA treated soil in both roots and shoots compare with other chelating agents. The chelating agents were found useful in enhancing phytoextractability of Pb by Zea mays. Hence, marginally Pb contaminated soil maybe remediated by adding chelating agents.