Bacterial And Gas Analysis Of Anomalous Limestone Groundwater In Renlou Coalmine,Huaibei Coal-field

On-site research was conducted taking into account the surrounding coalmines to find out the reasons for the abnormal groundwater quality of Renlou coalmine.By collecting the groundwater samples,analyzing the conventional ions and carrying out the high-throughput gene sequencing about the bacteria samples,this paper reveals that with the increase of the environmental sealing ability,the ion concentration of calcium and magnesium and the salinity decrease while the pH value increases.Piper graph,cluster analysis,data analysis by method of factor analysis,and gray correlative degree analysis show that the Taiyuan Formation limestone water of deep coalmine has a tendency of changing from typical limestone water to coal-bearing sandstone water.The results of gene sequencing show that there are large amounts of aerobic bacteria and anaerobic bacteria in the deep Taiyuan Formation limestone water.According to the anaerobic bacteria detected by gene sequencing such as Desulfobacterales and Methanosarcinales,it is proved that the hydrogeochemical process by microbes is one of the reasons for the change of groundwater quality in coalmines.The diastrophism of the fault causes the poor conditions of groundwater circulation,the high sealing ability and the low oxidation-reduction potential in local areas.The abnormal limestone groundwater lacks hydraulic relationship with other limestone groundwater,which brings about the exchange adsorption of cation and the appearance of sulfate's reduction effect,so that the concentration of HCO₃^-,K⁺ and Na⁺ in groundwater becomes high and that of SO4_<sup>2-,Ca²⁺ and Mg²⁺ is low,and the hardness of the groundwater decreases.In order to verify the sulfate reduction and the methanogenesis in the groundwater,high-throughput gene sequencing is used to detect the bacteria in the abnormal groundwater samples in Renlou coalmine.The results show that there are large amounts of sulfate reducing bacteria and methanogenus archaeas in the Taiyuan Formation limestone groundwater.Through the comparison of gene sequences,it is found that the sulfate reducing bacterias and the methanogenus archaeas are widespread in the groundwater in the deeper part of coalmines.It means that H₂S and CH₄ gas are generated continuously in coalmines because of the activity of microorganisms.The detection of the coalbed methane finds that CH₄ is the main hydrocarbon gas.Multiple hydrocarbon gas detected includes C₂H₆ and C₃H₈,and the concentration of CO₂ in non hydrocarbon gas is less than 5%.So it is the typical biogenic gas.