| Soils contaminated with metals pose a major environmental and human health problem, which is still in need of an effective and affordable technological solution.The phytoremediation is a cost-effective "green" technology based on the use metal-accumulating plants to remove toxic metals. In phytoremediation process, Fe, Mn mobility and the change of Fe, Mn fractionations were controlled by the physiochemical properties of the environmental, and Fe, Mn fractionations impacted on the toxic levels of metal. The success of reclamation schemes is dependent greatly upon the choice plant species and their methods of establishment. Chelator induced phytoremediation technology is plays an important role on the repair of metal pollution environment. In particular, substrate of EDTA has been used to restore contaminated soil in recent years, however, little is known about the effect of EDTA on various forms and mobility of Fe, Mn and metal extraction.Ornamental plants Rivina humilis L. as experimental material. A complete nutrient solution culture experiment was conducted to study the effects on the growth, physiological characteristics, the absorption, accumulation and transfer of Fe, Mn and exogenous chelator (EDTA) for Fe, Mn chemical enhancement mechanism under the concentration on gradient experiment with single Fe2+,Mn2+ and their Combined stress. At different Fe2+,Mn2+ concentration, the uptake and accumulating of Rivina humilis L. For necessary nutrient elements kept normal and the concentration of necessary nutrient elements made normal plant species grow.The results showed that:①In the polluted environment of Fe2+ and Mn2+, Rivina humilis L. is susceptible to Fe2+ poisoning, and high resistance to Mn+.The low concentration of Fe2+, Mn2+ can significantly promote the growth of plant rouge, but the high concentration suppresses its growth.Fe2+ toxicity critical concentration is 0.5 mmol·L-1 and the concentration of poison tolerance is less than 1.25 mmol·L-1; Mn2+ toxicity critical concentration is 4 mmol-L-1 and the concentration of poison tolerance is less than 8 mmol·L-1. Moreover, it was stand with high resistance to manganese and vulnerable to iron toxicity. WhileMn2++Fe2+combined stress treatment the best density combination is 6+0.5 mmol·L-1, but 2+1 mmol·L-1 density combination poisons the degree to the rouge grass to be most serious.②The tendency which along with Fe2+, Mn2+ and the combined stress concentration increased, after the rouge plant biomass assumes rises, to fall first, the density which Fe2+, Mn2+ and Mn2++Fe2+ are suitable respectively is:0.5 mmol·L-1,4 mmol·L-1 and 6+0.5 mmol·L-1. Compare the Fe+, Mn2+ single and combined stress on the grass under the rouge Fe, Mn absorption, accumulation and transfer of the amount of Rivina humilis L. on the metal Mn draw rouge the coercive environment, adaptability is stronger than Fe.③Exogenous EDTA treatment of stress in the manganese added Rivina humilis L. biomass, the promotion of Mn to the shoots from the underground parts of the transfer efficiency, the rouge grass on the Mn tolerance and accumulation capacity, which EDTA concentration of 2.5 mmol·L-1 to enhance the best results, so add the chelating agent EDTA Rivina humilis L. after the restoration of manganese pollution of the environment has great potential for use. These results indicate that Rivina humilis L. on the manganese rouge great patience and enrichment capabilities, due to the greater plant biomass, growth rate high, so it may be used in urban ecological environment landscape plant phytoremediation of manganese pollution in the provision of scientific basis and theoretical basis.
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