Effects Of Heavy Metal Pollution On Enzyme Activity And Microbial Ecological Diversity In Bayan Obo Mining Area

Nowadays,with the rapid development of modern cities and industries,the impact of heavy metal pollution on soil has attracted more and more attention at home and abroad.Mining is a major source of heavy metal pollution in soil.The mining of mineral resources will produce a series of tailings,waste liquid,waste residue,waste gas,etc.which can not be used by human.The harmful substances such as heavy metals will also migrate to the atmosphere,soil,underground water,causing serious damage to the surrounding ecological environment,and threatening the survival of plants,animals,microorganisms and even human beings near the mining area.Therefore,in this study,the soil around Bayan Obo mining area in China was taken as the research object to explore the microbial community structure and diversity in the soil,the abundance of heavy metal resistant genes in the soil and the changes of five enzyme activities.The main conclusions are as follows:(1)The heavy metal content in the soil varies from large to small: Mn> Zn> Pb>Cu> Cd> Hg.The maximum concentrations of six heavy metals are located in the mining area,and the pollution rule is mining area > residential area > control area.All samples are alkaline soil with high organic matter content.Except for the control point,they are all the first-class organic matter content,all the points are higher than the background value of Inner Mongolia.The heavy metal content of the mining area soil is significantly higher than the residential area and the control area,indicating artificial mining Increases heavy metal pollution in the soil.(2)There are differences in the structure and function of microbial community in different regions.Actinobacteria is the main microbial flora in the soil of the mining area,and Proteobacteria is the main microbial flora in the residential area;only resistant microorganisms such as microorganisms appear in the mining area.and the proportion of ABC transporter and two-component regulation system is the largest in the prediction of soil metabolic function in the mining area.In the case of long-term heavy metal pollution,the original microbial community composition and function were changed.(3)Heavy metal pollution will affect the abundance of heavy metal resistance genes.The more severe the heavy metal pollution,the greater the czcA,czcB,czcC,and czcD gene abundance,indicating that in the presence of heavy metal ions,the strain can make adjustments to express a large number of resistance genes in response to environmental changes.The czcD gene was significantly correlated with Zn(p<0.05),and extremely significantly positively correlated with Cu(p <0.01),and had no correlation with other physical and chemical properties(p> 0.05).(4)There are differences in enzyme activity in different regions.High concentrations of heavy metals can inhibit the activities of catalase and sucrase.Artificial mining activities have affected the distribution of heavy metals,and they also have an impact on phosphatase activity.There is no obvious pattern of heavy metal content and urease activity.The activities of catalase and sucrase are significantly negatively correlated with w(Mn),w(Zn),w(Pb)and w(Cd)(p <0.01),size distribution: control area> residential area> mining area.Phosphatase activity size distribution: mining area> residential area> control area.Alkaline phosphatase is very significantly positively correlated with silt,extremely negatively correlated with sand,significantly positively correlated with TN,and significantly negatively correlated with w(Cu)(p < 0.01).