| Cadium and Mercury were the worst or most popular pollutants, respectively, they could transport and transform in environment through dissolution, sedimentation and so on. Due to food chain,bioconcentration and biomagnification, Cd and Hg could harm human beings health. Currently, the main restoration of Cd and Hg in soil were physics, chemistry, microbial remediation and other projects. The soil contained low concentration of Cd and Hg, those means had several shortcomings, such as small benefit areas, secondary pollution, big environmental impact. Phytoremediation had broad application prospects, Ramie is a kind of perennial economic fiber crops. Under the condition of enough water and heat, ramie can grow fast, have high yield and economic benefit is remarkable. Because of these, it came to become topics in the study on soil respiration at home and aboard.Actually in the process of soil restoration, the effect of restoration by ramie is not ideal for mercury, cadmium.in order to improve the repair efficiency of ramie, this study proposed to use the biological chelating agent EDDS and non-biological chelator EDTA to induced ramie repair Hg/Cd contaminated soil. Also it used soil culture experiment to study the influence of Hg/Cd content of various forms in the soil by EDTA and EDDS. At the same time, it was analyzed the change of ramie biomass, the membrane lipid peroxidation level and the antioxidant enzymes(SOD, POD, CAT) of ramie leaves, the concentrations of Hg/Cd in different parts of ramie under the different concentration of EDTA and EDDS. Therefore, it could provide part of basis for restoration of the ramie for soil heavy metal pollution. The results were all as follows:(1) the content of exchangeable Hg and Cd was increased significantly with the increase of concentration of EDTA and EDDS, it included that EDDS and EDTA can effectively activate Hg and Cd. At the same time, applying the EDDS, exchangeable Hg and Cd are higher than applying EDTA, compared with the control,it respectively increased by 19.89%~29.52% and 70.30%~103.63%, it indicated that the activation effect of EDDS are better than EDTA. In the soil, the content of Cd for residue > acid extractable states > is square one > oxidation state, and Hg content for the residue state > but also square one, but oxidation state > acid can be extracted.(2) Compared with the use of ramie plant repair, add EDTA and EDDS two kinds of chelating agents can promote the absorption of ramie of mercury and cadmium, and with the increase of EDTA and EDDS concentration, the mercury, cadmium content of ramie increased significantly, applied EDTA, ramie root, stem and leaf of mercury and cadmium content respectively is 0.97 ~3.70 times and 0.26~1.59 times; 0.98 ~3.19 times and 0.98 ~3.19;1.12 ~4.17 times and 2.27 ~4.23 times compared with the contrast; applied EDDS, ramie root, stem and leaf of mercury and cadmium respectively which compared with the contrast were 1.07 ~7.42 times and 0.30 ~0.59 times; 0.32 ~ 1.27 times and 0.22~0.94 times; 1 ~3.96 times and 0.42 ~3.25 times, and the contents of mercury and cadmium was root > stem > leaf.(3) In promoting ramie the mercury, cadmium absorption,at the same time, application of EDTA and EDDS will makes the reduction in Ramie aboveground biomass, and were in control of the 4.35%-35.74%, 23.28%-44.34%, increased the content of MDA in leaves of ramie, and the activity of SOD and POD decreased. Overall, this showed that applying EDTA and EDDS will have adverse effects on the ramie growth. |
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