| As mining and smelting activities become more frequent,large amounts of heavy metals enter the soil and water bodies,resulting in increased levels of heavy metals in the vicinity,which seriously affects the lives of society and people.As the largest antimony mine in the world,Hunan Xikuagnshan has become a hot spot for scholars in recent years.At present,the bioremediation methods of soil heavy metal pollution are mainly based on plant remediation technology.Studies have shown that Broussonetia papyrifera has a certain remediation effect on contaminated soil in tin mines.However,its heavy metal enrichment ability has not yet reached the hyper-accumulated level,and the biomass and the availability of heavy metals will also affect the enrichment effect of B.papyrifera on heavy metals.Related studies have shown that plant growth promoters can promote the growth of plants while enhancing the effectiveness of heavy metals,thereby enhancing the enrichment effect of plants on heavy metals and enabling plants to achieve better repair effects.Therefore,this study aims to strengthen the enrichment effect of B.papyrifera on heavy metals by screening resistant growth-promoting strains,thus providing theoretical support for the remediation of heavy metal contaminated soil in tin mines.The main research contents and conclusions are as follows:(1)Through the investigation of the soil of Xikuangshan in Hunan,the content of various heavy metals was measured,and the types of heavy metals with serious potential ecological risks in the soil were explored.It was found that the soils of Sb,Hg and Cd in the Xikuangshan of Hunan Province reached heavy pollution and had high potential ecological risks.(2)The high-throughput sequencing technology was used to study the microbial community structure and diversity of the rhizosphere soil of B.papyrifera,and to explore the microbial flora associated with Sb,Cd,and Hg in the rhizosphere of B.papyrifera.The results showed that: a.The higher abundance in the soil is Proteobacteria;b.p H and OM significantly affect the microbial community,and these microbial groups are positively correlated with heavily polluted heavy metals Sb,As,Cd,and Hg;c.The dominant bacterial groups in the soil of B.papyrifera rhizosphere that are positively correlated with the three heavy metals Sb,Cd and Hg are Gammaproteobacteria,Deltaproteobacteria,Sphingobacteriia,Actinobacteria,Acidmicrobiia,Thermoleophilia,Subgroup＿6and Blascocatellia.(3)By screening strains tolerant to Sb,Cd and Hg in the soil of Xikuangshan,and carrying out the identification of their ability to produce IAA,ACC and siderophore,this experiment finally obtained 2strains with strong growth promoting ability G-1 and G-4,determined by 16 s r DNA sequence,the results show that G-1 and G-4 are Stenotrophomonas and Raulella,both of which belong to Proteobacteria,Gammaproteobacteria.(4)Explore the effects of 2 strains on B.papyrifera growth and heavy metal enrichment effect through pot experiment.The study found that inoculation with plant growth promoters significantly increased plant height and biomass,promoted B.papyrifera growth,and increased the content of chlorophyll a and chlorophyll b to reduce the toxic effect of heavy metals on chloroplasts,and the degree of oxidative stress of plants is relieved to a certain extent.Moreover,the plant growth promoting bacteria significantly increased the accumulation of Sb,Cd and Hg in B.papyrifera,and the enrichment coefficient increased,indicating that the growth promoting strain can increase the enrichment effect of B.papyrifera on heavy metals. |
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