Study On The Synergistic Remediation Of Lead And Cadmium Contaminated Soil By Four Landscape Plants And Microorganisms

In this study,a tolerant strain was screened and isolated from the soil of the Pb and Zn slag dump site,and the Cd tolerance characteristics of it and the two strains stored in the laboratory were studied;ryegrass,rudbeckia,osmanthus,and gardenia were selected to study four The combined repair effects of landscape plants and tolerant strains of Purpureocillium lilacinum,Paecilomyces sp,and Stenotrophomonas maltophilia,the research results are as follows:（1）One strain of Pb²⁺（2500mg/L）-tolerant fungus,Purpureocillium lilacinum,was isolated and screened out of soil samples collected from Pb and Zn slag stacking sites.The Cd tolerance of Purpureocillium lilacinum and Paecilomyces sp was 400 mg/L,and the Cd tolerance of Stenotrophomonas maltophilia was 200 mg/L.（2）When the Pb concentration is 1500mg/kg,the simultaneous application of Cd can inhibit the increase of the dry weight of Rudbeckia and Osmanthus fragrans,has no significant effect on the dry weight of ryegrass,and has a certain promotion effect on the dry weight of gardenia.The Cd concentration is 25mg It started to have an inhibitory effect on the dry weight of gardenia flowers at the time of each heavy metal treatment;the Pb transport ability of Rudbeckia in each heavy metal treatment was stronger than that of ryegrass,osmanthus and gardenia;when the Pb and Cd concentrations were 1500 and 1mg/kg,the black Wheatgrass can efficiently accumulate Pb,and ryegrass,osmanthus and gardenia can efficiently accumulate Cd.（3）Paecilomyces sp and Stenotrophomonas maltophilia can effectively alleviate the toxicity of Pb and Cd to osmanthus and gardenia.The secretion of the strain promotes the use of cell wall to fix heavy metals in gardenia and prevents heavy metals from entering the cells.Maintain normal physiological metabolism and promote plant growth.Both single inoculation and double inoculation of strains can effectively alleviate the toxic effects of Pb and Cd on ryegrass;Pb and Cd have more obvious toxic effects on the roots of Rudbeckia;when Rudbeckia and PL+PS are synergistic,they have the best effect on the above-ground biomass.Excellent;both single inoculation and double inoculation treatments have obvious effects under simultaneous stress with Cd concentrations of 5mg/kg and 25mg/kg.（4）Under Pb and Cd stress,PS+SM had little effect on the Pb transport and Cd transport capacity of Osmanthus fragrans and Gardenia.When Pb and Cd are added at 1500 and 1 mg/kg,PS+SM has almost no effect.The Cd accumulation ability of both plants has a certain promotion effect,and shows a concentration effect.The ability of plants to accumulate Pb and Cd is related to the concentration of Pb and Cd treatments;both single and double inoculation treatments can effectively enhance the ability of plants to accumulate Pb and Cd,and both are more conducive to improving the ability of plants to accumulate Cd.And the effect of double inoculation treatment is better than single inoculation.Strain single inoculation treatment can improve the Pb migration ability of ryegrass and inhibit the upward migration of Cd;under the common stress of Pb and Cd（1mg/kg）,double inoculation treatment can improve the migration ability of ryegrass to Pb and Cd;single and double The inoculation treatment is more conducive to improving the Pb transport ability of chrysanthemum.（5）Both single inoculation and double inoculation of strains can effectively promote the active content of Pb and Cd in the soil,and increase the absorption of heavy metals by plants.The promotion effect of double inoculation is relatively better than that of single inoculation.