| Coal occupies the dominant position of the consumer energy in China,and is the lifeblood of the economy.In recent years,water resource shortages and inrush water accidents in mines have been restricting the sustainable development of Chinese coal industry.Therefore,solving the problem of water shortage and water inrush disaster in mining area is of great significance to socio-economic development.In this study,the groundwater in different aquifer systems in Xinji mine area,Huainan city,Anhui province,was systematically tested for its conventional ion(Na+,Ca2+,Mg2+,Cl-,SO42-,CO32-and HCO3-)concentrations,and groundwater in each aquifer was systematically evaluated using various water quality evaluation indicators(WQI,SAR,%Na+and RSC)for drinking and irrigation purpose,and used conventional water chemistry methods(Gibbs diagram,Ca2+-Mg2+-HCO3--Na+diagrams,and ion ratios)in combination with mathematical and statistical methods(correlation analysis,R-model cluster analysis,and US EPA Unmix model analysis)to explore the qualitative and quantitative sources of major ions in groundwater,followed by Q-model cluster analysis,factor analysis,and the Unmix model selects pure groundwater samples of the major aquifers gradually,then the water source identification model of mining area was constructed.The results are as follows:(1)In the Loose layer aquifer(LA),Na+and Ca2+are the main cations in second(LSA)and third(LTA)aquifer,and HCO3-have a high content.Na+and Cl-are the dominant cation and anion in the fourth aquifer(LFA).With the increase of depth(from LSA to LFA),TDS and pH value of groundwater gradually increase,and the hydrochemical type shows the transition trend of HCO3-Ca HCO3-Na to Cl-Na.For the samples from the coal-bearing aquifer(CA)and the taiyuan limestone aquifer(TA),Na+and Cl-have the highest concentration,followed by HCO3-,and the hydrochemical types of all water samples in the two aquifers are Cl-Na type.In terms of TDS,all the LSA and LTA water samples and 58%of TA water samples are similar to the fresh water(TDS<1000 mg/L),while all of the samples from LFA and CA are highly mineralized.(2)Considering only the major ions and mineralization,WQI index shows that the LSA and LTA water are excellent drinking water,the LFA and CA water are not suitable for drinking without treatment,and the TA water belongs to medium and good water type.In addition,SAR,%Na+and RSC indicators show that all the LSA water samples and 70%of the TA water samples can be used for irrigation,while most of the groundwater in other aquifers cannot meet the requirements of irrigation water.Therefore,from an economic point of view,the current availability of treated LSA,LTA and TA water as a source of drinking and irrigation water for the mines may be an effective way to solve the problem of water shortage in the mining area.(3)Conventional hydrochemistry methods combined with correlation analysis,R-type cluster analysis,and Unmix model analysis show that the major ion of groundwater samples from LSA and LTA come from the dissolution of Ca2+-Mg2+minerals and siltstone,while the dissolution of salt rock and the weathering of silicate minerals responsible for the ion concentrations of the CA and TA samples.The chemical composition of groundwater samples from TA was related to the dissolution of carbonate and sulfate.(4)The model for water source identification using pure samples worked well,with an overall identification accuracy rate of 90%.The results of the model retest showed that the correct identification rate of the LFA water and the TA water was 100%,but 26%of the CA water samples were identified as LFA water,indicating that LFA water may have a certain degree of infiltration and recharge to the coal system,resulting in a certain hydraulic connection between them.Therefore,the threat from the LFA water should be prevented in the future production activities of the mine.At the same time,the threat of high-pressure water from the limestone aquifer should not be neglected.Figure:27 Table:18 Reference:93... |
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