Chelate-induced Technique Of Heavy Metal Contaminated Soil

The contamination of environment with heavy metals has become a wodd wide environmental problem, and receives great attention. It uses certain patience either the ultra accumulation plant can the excess absorption shift one kind of or several kind of heavy metal characteristic from the soil, through exerts the chelating agent to the soil in (for example EDTA, EDDS, citric acid and so on) can activate in the soil the heavy metal, enhances the heavy metal the biological validity, the promotion plant absorption, thus achieves in the reduced soil goal of the heavy metal content. This experiment that we take the three kind of main pollution metal Cu, Pb, Cr in black soil through the chelate - induced provides the basis of black soil In-situ and Ex-situ remediation with the appropriate chelating agent and contents. Through water, soil cultured and a series of method, studied the effect of Cu, Pb, Cr for wheat (T. aestivum L), rape(Brassica juncea Czern. et Coss) seed germination and growth and the effect of chelating agent for the wheat seed germination and the biological activity. The chelating agent induction under in the corn(Zea mays) absorption soil Cu, Pb pollution situation has carried out the experimental was. The main results as follows:(1) Wheat and rape were similar in the different growth stage to the heavy metal patient size, in the germination and seedling growth stage, all had the high patience to Pb and Cu, Cr were bad; Under Cu, Cr with low levels (20 rng·L^-1)stress seedling was suppressed growth completely, the root long was 22%, 37% compares with control. The effect of 3 kind of heavy metals for wheat and rape seedling growth were: Cu＞Cr＞Pb, Cr＞Cu＞Pb. Two kinds of plants had the high patience to the Pb.(2) Chelating agent compound stress can promote the seed respire; tion that indicated obviously antagonism between the chelating agents. The result compares with the control, when two kind of chelating agent compounded stress the chlorophyll content obvious increase under the low concentration and the chlorophyll content mean was bigger than the average content under the chelating agent single stress. This showed that the chelating agent compound stress was lower than under the single stress to the chlorophyll synthesis inhibitory action the inhibitory action. We increased EDTA and citric acid (CA) had inhibited soil catalase (CAT), along with chelating agent density increase, CAT' suppression rate also increased, EDTA was less than the CA inhibition to CAT.(3) The ability of EDTA activates Cu was corresponded to EDDS, the ability of EDTA activates Pb was increased to EDDS and CA activation was the least. Considered with the environmental safety, EDDS is the chelating agent which use to recommends at present can degrade completely in the 5～8 d cyclical intrinsic each kind of environment medium.