Soil Microbial Community Characteristics And Influencing Factors Of Typical Manganese Mining Areas In Hunan Province

Manganese(Mn)is mainly used in metallurgy and chemical industry,which is an important basic material for national economic development.However,Mn ore resources will cause serious environmental pollution during the production process of mining,smelting and piling,etc.Microorganisms,as indicators of environmental quality,are extremely sensitive to the environment.Microbial communities in soil can adapt to changes in survival conditions by adjusting the community structure and diversity.In this study,we collected tailing and forest soil(control)samples from seven typical Mn mining area in Hunan Province.The heavy metal content,basic physicochemical properties,extracellular enzyme activities and microbial(bacteria and fungi)communities in the samples were analyzed.The environmental drivers affecting the diversity and structure of microbial communities were identified.The results of the study can provide scientific basis and practical guidance for the remediation of heavy metal pollution in Mn mining areas of Hunan Province.The main conclusions are as follows:(1)Characteristics of environmental factors in Mn tailing slags and control soils:The contents of heavy metal were significantly higher in Mn tailing slags than control soils(P<0.05).Single factor pollution index showed that Mn,Cu,Pb,Ni and Cd in Mn tailing slags and Ni and Cd in control soils reached heavy contamination levels.The TOC,TP and EC values in Mn tailing slags were significantly higher than those in control soils,but enzyme activities of βG,NAG,LAP and ACP were reverse(P<0.05).(2)Bacterial community characteristics of Mn tailings and control soils:The Chao1 and Shannon index of bacterial community in Mn tailing slags were significantly lower than control soils.In addition,bacterial community compositions were significantly different between the two habitats(F=9.63,P=0.001).Proteobacteria(62.4%)and Actinobacteria(12.2%)were highly tolerant to long-term heavy metal contamination in manganese tailings slag.The bacterial network was less complex and more organized in Mn tailing slags than control soils,and bacterial species in the Mn tailing slags adapted to the heavy metal stress mainly through the cooperative cooperation among themselves(88%of positively correlated edges).(3)Fungal community characteristics of Mn tailings and control soils:The α-diversity of fungal community in Mn tailing slags and control soils showed similar characteristics with bacterial community.There were significant differences in fungal community compositions between the two habitats(F=3.65,P=0.001).Ascomycota(60.4%)and Basidiomycota(12.6%)were highly tolerant to long-term heavy metal contamination in manganese tailings slag.The cooccurrence network analysis showed that the fungal network in Mn tailing slag was more complex and less organized than the control soil,and fungal species in Mn tailing slags also adapted to heavy metal stress through synergistic cooperation among themselves(98%of positively correlated edges).(4)The driving environmental factors affecting microbial communities of Mn tailings and control soil:the diversities of bacterial and fungal communities in Mn tailing slags were significantly correlated with Mn,soil physicochemical properties and enzyme activities(P<0.05).Mn content,βG and NAG activity were the main factors affecting bacterial and fungal community structure in Mn tailing slags,while pH,AP content and ACP activity were the main factors driving bacterial and fungal community structure in control soils.The inhibitory effect of heavy metal contamination on the enzyme activity from Mn tailings slag may have significantly affected the nutrient utilization capacity and efficiency of microorganisms.