Effects Of Rhizobia And Pgpr Co-inoculant On Chelator And Microbial-assisted Phytoremediation Of Cu Contaminated Soil

With the exploitation of the mineral resources,the soil heavy metal pollution affect the Earth’s ecosystem and threaten the human living environment seriously and hinder the sustainable development of the economy.So the soil remediation technology is a matter of great significance.In this paper,throughing making a field survey,soil of abandoned mine area was selected as the research object,based on the analysis of the Cu concentration.In this study chose alfalfa(Medicago Sativa)as the remediation plant to absorb the heavy metal contaminated soil.A greenhouse pot experiment was carried out using the combined inoculation with S.meliloti CCNWSX0020 and P.mucilaginosus ACCC10013 to enhance phytoremediation to analysis the effect of the combined remediation and to research the effect of combined inoculation on the chelator and microbial-assisted phytoremediation.The main results are as follows:1.In the response experiment of plant to the combined inoculation,the addition of S.meliloti and P.mucilaginosus had a significant effect on the growth of Medicago Sativa.The plant combined inoculated with the S.meliloti and P.mucilaginosus grew well with the highest biomass,total N and the content of chlorophyll.The biomass of shoot and root in the combined inoculated treatment was 28.89% and 32.92% higher than the treatment without inoculation.The total N uptake of the combined inoculated treatment was 24.83%,16.84%and 3.54% higher than the treatment without inoculation and individual inoculated with P.mucilaginosus and S.meliloti.The Cu concentration of shoot in combined inoculated treatment with the highest value 44.57 ± 4.10 mg kg-1 was 1.15-fold than the treatment with no-inoculation.Therefore,S.meliloti and P.mucilaginosus will increase the shoots and roots of enrichment factor,and even the enrichment factor of S.meliloti was higher than P.mucilaginosus.2.In the process of chelator and microbial-assisted phytoremediation,S.meliloti and P.mucilaginosus effect the resistant ability of plant positively in the combined phytoremediation.With the EDDS application,the contents of MDA,H2O2 and O-2were significant increased than control.The combined inoculation will enhance the resistant ability of plant and decrease the MDA,H2O2 and O-2 content of shoots and roots significantly.Though the antioxidant enzyme system of plant decreased by EDDS,in the inoculated treatment,the SOD,CAT and APX contents of plant were higher than the treatment without inoculation.3.In the process of combined phytoremediation after the EDDS application,the high Cu concentration bioavailability in the soil was toxic to plant,but with the S.meliloti and P.mucilaginosus combined inoculated,the biomass of shoots and roots was also higher than the treatment without inoculation and individual inoculated with P.mucilaginosus and S.meliloti.The transfer coefficient and accumulation index after EDDS application increased significantly.Though the metal toxicity may result in decreasing some soil enzyme activities and microbial communities temporarily,the soil enzyme activities and microbial communities will be recover with the degradation of EDDS.EDDS will be absorbed by plant as nutrient and promote the soil nutrient cycle.The combined inoculated treatment could uptake more metal to decrease the metal content of polluted soil.