Groundwater Chemical Characteristics Of JiaWang Coal Field In Response To Mine Closure

The groundwater level will rise quickly when mine water is stopped to dischargeafter mines closure. Other underground aquifer will be polluted by mine waterthrough mining-induced fracture, fault and bad closed drilling. Therefore, the study ofchemical change of closed mine water have a great significance to mining area waterresources protection.Taking the closure mining area in Jia Wang, Xu Zhou as an study area, the paperhas done Water quality monitoring to the37water quality monitoring points, analyzedthe change in water quality of ground and surface water in abandoned coal mine andthe surrounding area, researched effects of water environment the mine closing bringsand combining with indoor simulating test, studied the evolution mechanism ofrepresentative pollutants in Mine water after it closed. Then, the author comes to theconclusion:(1) There is significance difference between mine water and commongroundwater in water quality. HCO-3is the main constituent of anion, in commongroundwater, Ca2+and Mg2+is the main constituent of cation. However, K+and Na+is the mainconstituent of cation and SO2-4is the main constituent of anion in common groundwater. Theconcentration of SO2-4can run up to1186.23mg/L, furthermore, the average value of TDSin mine water is1591mg/L, which is higher than common groundwater.(2) The water quality change has taken place for groundwater level rise after coalmine closure. The Ordovician groundwater isn’t influenced by mine water in localarea; however, the Quaternary groundwater is influenced. The value of pollutantconcentration exceeded national Ⅲ standard, including iron, manganese, sulfate andTDS.(3)15VOCs and14SVOCs have been tested in Groundwater, surface water andmine water in mine area totally; the detection rate is high while the detection ofcontent is all low.5kinds of typical organic pollutants have been screened among allmonitoring indicators and the percentage of the non carcinogenic risk valueaccounting for the non carcinogenic total risk value from big to small is successively:Methylene Chloride> Carbon Tetrachloride> Bis(2-ethylhexyl)phthalate>1,2–Dichloroethane> Benzene. They are not all over non carcinogenic risk value, so theydo not risk non carcinogenic to Exposed receptor. The percentage of the carcinogenic risk value accounting for the carcinogenic total risk value from big to small issuccessively: Carbon Tetrachloride>1,2–Dichloroethane> Methylene Chloride>Benzene。3kinds of organic pollutant are over standard limits and long term contactor drinking of exposed receptor would affect its health.(4) The simulation results of mine closure show that the water will be polluted bysome wastes in abandoned coal mine, such as gangue, scrap metals, timber, and so on.The residue pollution, like iron, manganese, sulfate and TDS, will be dissolved whengroundwater level rise after coal mine closure. The pollutant concentration is on theincrease as time goes on. The highest concentration of iron is1.29mg/L, twelve higherthan normal. The highest concentration of sulfate and TDS is472.52mg/L,3548.00mg/L respectively, exceeded national Ⅴ standard. Therefore, coal mineclosure will pose a threat to groundwater environment; the protection measure shouldbe taken at once.