Chelant Comparison for Assisted Phytoextraction of Lead in Two Contaminated Soils

Microcosm experiments with Brassica juncea were carried out to evaluate the potentiality of using chelators with a different levels of biodegradability for phytoextraction purposes in two lead contaminated soils. Oxalic acid (OSS) and ethylenediamine-N,N'-disuccinic acid (EDDS) were used at various concentrations (0.2, 2, 10 and 20 mM) and compared with EDTA 2 mM, which is the concentration typically used for lead assisted phytoextraction. All chelators increased Pb concentrations in plants compared with the control. The best efficiency was obtained with an EDDS 10 mM solution, reaching more than twice higher Pb concentration values for both soils compared to controls. Results indicate that EDDS is a valid alternative to EDTA for lead phytoextraction, while oxalic acid does not sufficiently solubilize this metal.