EFFECTS OF CHELATORS ON GROWTH, PHYTOEXTRACTION OF HEAVY METALS IN SOYBEAN (GLYCINE MAX L.)

摘要

The effects of ethylene diamine tetraacetic acid (EDTA), triethanolamine (TEA) and citric acid application on metal extractability from a multiply metal-contaminated soil, as well as on their uptake and accumulation by soybean (Glycine max L.) were investigated. Plants were grown in soil collected from a contaminated field site and polluted by Cu, Zn, Pb, Cd. After 21 days of plant growth, pots were amended with EDTA, TEA or citric acid at 1 or 5 mmol kg~(-1) soil. Control pots were not treated with any chelator. Harvest of plants was carried out 1 week after chelator addition. The results showed that EDTA was more effective than other two chelators at increasing the concentration of Cu in soybeans. The application of 5 mmol kg~(-1) soil EDTA to soil significantly increased concentrations of Cu in shoots and roots, with maximum levels of 115.2 and 754.0 mg kg"1 dry weight (DW), respectively. Concentrations of Zn, Pb and Cd in shoots or roots were also higher in the soybeans treated with EDTA than in those treated with TEA or citric acid. Desorption of metals from the soil increased with chelator concentration. EDTA was more effective than TEA and citric acid in solubilizing the metals. It was concluded that chelators were most effective on Zn extraction followed by Pb, whereas Cu and Cd extracction were very poorly affected by chelators.