Adsorption Characteristics Of Soil Microorganisms For Cadmium

Soil heavy metal pollution is one of the most serious environmental problems,and seriously affects environmental quality and human health.Soil cadmium pollution is one of the main types of heavy metal pollution in soil.Soil cadmium pollution has a wide range and long duration,strong toxicity,and high environmental risk,which is closely related to human survival and development.The bioremediation method in the cadmium-contaminated soil remediation method is environmentally friendly and low in cost,and has broad application prospects in the field of cadmium pollution remediationThis study collected soil samples from high-cadmium-contaminated farmland in Xiwu Town,Zhejiang Province,and domesticated and screened strains with high tolerance to cadmium.The strain identification was carried out,and the adsorption characteristics of the resistant strain to Cd²⁺were studied.Finally,the repairing effect of the resistant strain on the high cadmium contaminated soil was investigated.The main research contents and conclusions are as follows:Three fungi with high tolerance to cadmium were domesticated and isolated from the collected high-cadmium contaminated soil samples,,named strains L1,L2,and L3.The tolerance concentration of cadmium of three strains in liquid medium reached 2400 mg/L.According to ITS sequencing combined with phylogenetic tree analysis,LI and L3 were identified as Aspergillus and L2 as Talaromyces.The adsorption test was carried out using the isolated tolerant bacteria as an adsorbent.The results showed that the maximum adsorption capacity of Cd²⁺by the three strains reached 137.5mg/g?87.5 mg/g?68.2mg/g,respectively.In the presence of Cd²⁺,the growth of the strain was also inhibited.Scanning electron microscopy?SEM?showed that the surface of cadmium-tolerant bacteria was rough,and many depressions provided a good site for adsorption of cadmium.The strains L1 and L2 were mixed with bran and sawdust respectively to prepare microbial inoculum,which was added to high-cadmium contaminated soil to study the effects of mixed microbial agents on the forms of cadmium,enzyme activity and microbial quantity of cadmium in soil.The results showed that microbial agents could reduce the exchangeable cadmium content of high cadmium contaminated soil,increase the oxidizable cadmium,reducible cadmium and residual cadmium content,and have a good fixation effect on cadmium.At the same time,the addition of microbial agents increases the number of microorganisms in high cadmium contamination soil,and the activities of catalase and urease are also enhanced.It shows that the experimental microbial agent has certain repairing effect on high cadmium contaminated soil.