Microbial Driving Mechanism Of Mine Water Quality Formation And Evolution In Xinjulong Coal Mine

A large amount of mine water produced by coal mining has become a burden for the prevention and control of groundwater pollution in coal mine areas,so it is necessary to identify the characteristics and influencing factors of mine water quality.Microorganisms participate in the formation and evolution of mine water quality through element cycling.Based on the National Key R&D Program of China:"Materials and Technologies for Groundwater Pollution Prevention and Control in Coal Mine Areas",the groundwater and mine water with high TDS and high SO₄^2-in Xinjulong Coal Mine who is the demonstration site was studied.Through sampling the whole process of mine water（generation,collection and discharge）in the producing mine,and conducting laboratory simulation expeiments,the microbial community and hydrogeochemical characteristics of different zones in the underground coal mine were obtained.Besides,the driving mechanism of microorganisms on the change of SO₄^2-concentration was preliminarily defined.The main achievements are as follows:（1）The hydrogeochemical parameters and microbial community structure of samples underground mine showed displayed apparent zone-specific patterns.The richness and diversity of microbial community in mine water and sediment samples from goaf were the lowest.Proteobacteria,Actinobacteria,Firmicutes were the main phyla.The dominant bacteria genera mainly include Acinetobacter,Hydrogenophaga,Pseudomonas.（2）Coal mining activities changed the living environment of microorganisms,and microbial communities responded by changing composition.The relative abundance of SRB（Sulfate-Reducing Bacteria）in the goaf was high.The goaf is the key area for the prevention and control of groundwater pollution in coal mine.With the time since goaf closure,the proportion of SRB increased significantly.At the same time,it was found that the concentration of SO₄^2-in the goaf water decreased by 42%within 12 years,indicating that long-term closed goaf have a certain self-cleaning ability under the action of multiple fields.（3）The results of laboratory experiments showed that the influence of sterilization and closure conditions on the concentration of SO₄^2-is more significant.In experimental group,p H and SO₄^2-increased first and then decreased,while TDS decreased gradually.The relative abundance of SRB in the sterilization group was higher than that in the experimental group,which resulted in obvious desulphidation in the early stage of the experiment.The rate curve of SRB reduce SO₄^2-fitted based on experimental data proves that in the case of insufficient carbon source in the later stage,the impact of SRB on SO₄^2-will gradually weaken.（5）The abundance of sulfur metabolizing genes corresponds to the concentration of SO₄^2-,which proves that microorganisms participate in the material cycle through gene expression and metabolic activities,and then drive the change of components in mine water.The difference in metabolic genes abundance between the control groups（sterilization and closure conditions）and the experimental group basically corresponds to the difference in SO₄^2-concentration,which also proves that sterilization and closure conditions have a more significant effect on SO₄^2-concentration.