The Effect Of Chelating Agents And AM Fungi For Phytoremediation Of Heavy Metals Contaminated Soils

The restoration of heavy metal contaminated soil has become a global commonconcern hot issues of environment. Because of its good effect, less investment, ease ofmanagement and operations, phytoremediation is considered as a eco-friendly greensitu remediation technologies. In recent years, at home and abroad, extensiveresearches adout metal chelating agents in chemistry-plants joint repair andmycorrhizal fungi in the microorganisms-plants joint repair have been carried out.Chelating agents can increase the bioavailability of heavy metals, increasing theamount of metals absorbed and extracted by plants, however, chelating agents andmetal chelates inhibit plant growth, affecting the efficiency of plant extracts.Mycorrhizal mycelium can promote the plants growth, improving the tolerance ofplants to heavy metals. If combined the chelating agent and mycorrhizal, in theory,the advantages of both should be able to play: the chelating agents and metal chelatesheavy damage on the plants that can reduced by the high activity of mycorrhizal,greatly improving the efficiency of phytoremediation.Through the greenhouse pot experiment, four chelating agent EDTA, EDDS,AES, IDSA, and mycorrhizal and combined mycorrhizal AM and chelating agents inthe promotion of efficiency of plant uptake of heavy metals were studied, theconclusions following:1. Chelating agents, EDTA, EDDS, AES and IDSA promoted the absorption ofheavy metals, AM mycorrhizae can promote the plant growth, and enhance the plantof resistance to heavy metals in the environment. Adding a chelating agent and withthe inoculation of AM fungi can uptake and accumulate more heavy metals for cornthan the single inoculation of AM fungi or the single adding a chelating agent, and thecombination of chelating and AM fungi reinforces the effect of plant extracts.2. The Cd concentration of corn on the ground with the new chelating agent AESand IDSA was significantly greater than that of the control, EDTA and EDDS. The Zn,Cu and Pb concentration of corn on the ground with AES were significantly greaterthan control and other chelating agents, but the concentrations of Pb in maize roots was the greatest. The concentration of Zn in corn shoot with IDSA was significantlygreater than the control and EDTA. The Cu concentration of corn on the ground androot with IDSA was significantly greater than the control and EDTA. The corn withIDSA aboveground Pb concentrations were significantly greater than the control. AESis stronger than IDSA in the desorption of heavy metals.3. AM fungi changed the form of heavy metals in the rhizosphere soil, and theform of heavy metals transferred from loose combination of state to tighten, reduceingthe bioavailability of heavy metals, and reducing the poison on the host plant becauseof excessive heavy metal.4. With the chelating agent, the content of MDA in corn leaves inoculated, saidthe enhancement poisoning of heavy metals on the corn. Inoculation with AMmycorrhizal maize improved the leaves of SOD, CAT and APX activity, andenhanced the resistance of the corn on the excess heavy metals in the environment.5. AM fungi on the desorption of heavy metals in the soil is not obvious, thedesorption of heavy metals did not change significantly over time. EDTA on thelonger duration of desorption of heavy metals, plant after the harvest, theconcentrations of heavy metals in the soil still increasing, EDDS, AES and IDSAmade the concentrations of heavy metals in the soil decreased until a stable state overtime.