Chelators including DTPA (diethylene triamine pentaacetic acid) and oxalic acid were selected for inducing phytoextraction of heavy metals (HMs) from Pb-, Tl-, and Pb-Tl- contaminated soil, in which heavy metals leakage was highly remarkable. Results showed that compared with the control group without chelating agent under planting conditions, the extraction efficiency (i.e., uptake coefficient) of Pb, Tl increased by 86%, 43% from Pb-Tl- contaminated soil in the presence of oxalic acid, and there was no significant change in heavy metal leakage under rainfall conditions. It was the best phytoremediation scheme in this work. Under rainfall conditions, the HMs concentration in the leachate showed a linear decreasing trend. Acid rain promoted the leakage of heavy metals, and the average leached amount of Tl increased by 1.47 times under acid rain conditions. However, for Pb, DTPA was the main influencing factor, followed by acid rain.

Abstract. In this paper, the effects of EDTA and EDDS as chelating agents, chelating-induced maize remediation on Tl-contaminated soils and their heavy metal leakage characteristics under rainfall conditions were studied. The results showed that both EDTA and EDDS could promote the uptake of Tl by maize, and EDDS could further promote the transfer of Tl from maize roots to shoot, and the effect of EDTA was weaker; The content of Tl in the leachate during the leaching process obeys the linear decrease rule with increasing rainfall .Under the condition of acid rain, the concentration of Tl was higher than that of non-acid rain in the leachate of EDDS chelating induction.