Study On The Migration And Transformation Of "NH₄⁺?NO₂^- And NO₃^-" In Super Deep Groundwater

The research area of Kaifeng City,Henan Province,which has been developed and utilized by geothermal water,is used as the research area,and the ultra deep pore type geothermal water with deep buried depth as 800-1400m is used as the research object.First,the characteristics of"NH₄+?NO₂-and NO₃-"in geothermal water are analyzed through outdoor sampling and testing.Then the variation trend of the concentration of"NH₄⁺?NO₂^-and NO₃^-"under different temperature and water pressure Conditions was obtained through the laboratory simulation column experiment,and the effect of temperature and pressure on the transfer and transformation of"NH₄⁺?NO₂^-and NO₃^-"was clearly defined.The conclusions are as follows:?1?The vertical distribution of"NH₄+?NO₂-and NO₃-"in geothermal water in Kaifeng:With the increase of buried depth,nitrate nitrogen and nitrite nitrogen in geothermal water have a decreasing trend,and the ammonia nitrogen concentration has little change.pH,EC and TDS all increase with the increase of buried depth.This is related to the increase in the temperature with the increase of buried depth.?2?the conversion rate of nitrate nitrogen at 45 C is higher than 25,and the concentration of nitrite nitrogen at 45 C is more than 1mg/L in the middle and late stages of the experiment,which is related to the incomplete denitrification of nitrate.The nitrite nitrogen at 25 C showed a downward trend in the late experiment,and its concentration was always smaller than the injected 1mg/L,which was related to the reduction of nitrite and the weak nitrate reduction.Under the two Conditions,the concentration of ammonia nitrogen fluctuated near the background value,which was related to the strong adsorption of ammonia nitrogen by the research soil.Under the two Conditions,the change trend of inorganic nitrogen and EC was consistent with the trend of nitrate nitrogen,and the pH of leaching solution was weakly alkaline.?3?The conversion rate of nitrate nitrogen under 0MPa was higher than that of9MPa,which indicated that the increase of hydraulic pressure inhibited the transformation of nitrate nitrogen.Under the Condition of 0MPa,the concentration of nitrite nitrogen still had an increasing trend in the later stage of experiment,while the concentration of nitrite nitrogen had stabilized in the later stage under 9MPa Condition.Under two Conditions,the concentration of ammonia nitrogen fluctuates near the background value,but the concentration of ammonia nitrogen at 0MPa is slightly higher than that of 9MPa,which indicates that the increase of water pressure can strengthen the adsorption of ammonia nitrogen in water bearing medium.Under the two Conditions,the change trend of inorganic nitrogen and EC was consistent with the trend of nitrate nitrogen,and the pH of leaching solution was weakly alkaline.