A microcosm experiment was conducted to compare how different chelating agents enhance the phytoextraction of lead (Pb) by Mirabilis jalapa from an artificially Pb-contaminated soil. Chelating agents used included ethylene diamine tetraacetic acid (EDTA), nitrilotriacetic acid (NTA), ethylene diamine disuccinic acid (EDDS), oxalic acid, humic acid, citric acid and tartaric acid, with concentrations ranging from 0 to 2000 mg/kg. Results show that with increasing concentrations of chelating agents, the concentrations, bioaccumulation coefficients, and translocation factors of Pb in M. jalapa gradually increased. Of all chelating agents used, the concentrations, bioaccumulation coefficients and translocation factors of Pb in M. jalapa were higher for EDTA and NTA than for the other chelating agents. Given the potential environmental risks of EDTA, we recommend NTA be used as a suitable chelating agent to increase the phytoremediation of Pb-contaminated soil with M. jalapa.
Keywords: Bioaccumulation coefficient; EDTA; Metal; NTA; Phytoremediation; Translocation factor.