Chelate-Assisted Phytoextraction of Cadmium and Lead using Mustard and Fenugreek

Abstract

A screen-house experiment was conducted to study cadmium (Cd) and lead (Pb) phytoextraction using mustard and fenugreek as test crops. Cadmium was applied at a rate of 20 mg kg−1 soil for both crops, and Pb was applied at 160 and 80 mg kg−1 soil for mustard and fenugreek, respectively. The disodium salt of ethylenediamine tetraacetic acid (EDTA) was applied at 0, 0.5, 1.0, and 1.5 g kg−1 soil. Dry-matter yield (DMY) of both crops decreased with increasing rates of EDTA application. Application of 1.5 g EDTA kg−1 soil caused 23% and 70% declines in DMY of mustard and fenugreek shoots, respectively, in the soils receiving 20 mg Cd kg−1 soil. Similarly, in soil with 160 mg Pb kg−1 soil, application of 1.5 g EDTA kg−1 resulted in 25.4% decrease in DMY of mustard shoot, whereas this decrease was 55.4% in fenugreek grown on a soil that had received 80 mg Pb kg−1 soil. The EDTA application increased the plant Cd and Pb concentrations as well as shoot/root ratios of these metals in both the crops. Application of 1.5 g kg−1 EDTA resulted in a 1.50-fold increase in Cd accumulation and a 3-fold increase in Pb accumulation by mustard compared to the control treatment. EDTA application caused mobilization of Cd and Pb from carbonate, manganese oxide, and amorphous iron oxide fractions, which was evident from decrease in these fractions in the presence of EDTA as compared to the control treatment (no EDTA).