Effects of Chelators on Species and Bioavailability of Cadmium in Soil to Daucus carota var. sativa and Brassica juncea var. multiceps

A pot incubation study was conducted to investigate the feasibility of using Daucus carota var. sativa (carrot) and Brassica juncea var. multiceps (potherb mustard) for phytoremediation of Cd-contaminated soils and evaluateing the effects of chelating agents (EDTA, EGTA, DTPA and citric acid) application on metal uptake by both plants. It was shown that, the content of water soluble and exchangeable Cd was increased by 19.3%~22.4% induced by 6 mmol kg^-1 EDTA, EGTA and DTPA and the bioavailability of Cd was improved. With the application of this three chelators at the rate of 3.0-7.0 mmol kg^-1, the uptake of Cd was all enhanced by the test plants more or less, with 4.0 mmol kg^-1 EGTA maximizing Cd absorption by carrot and 6.0 mmol kg^-1 EDTA doing by potherb mustard, which was 1.96 and 2.9-fold of the controls, respectively. Cd uptake could not be enhanced by citric acid. Although potherb mustard presented poorer Cd uptake ability than carrot did, it produced a higher biomass with a fast growth rate and a better metal tolerance under all treatments.