Abstract: The accuracy of ¹⁴C age correction mainly depends on the identification of the factors affecting the variation of ¹⁴C activity in the process of formation of dissolved inorganic carbon and its evolution. Yinchuan plain has been taken the as case study and mass equilibrium reaction model and isotope mass transfer model have been employed to simulate the inverse geochemical reaction path of deep groudwater in Yinchuan plain and then to correct ¹⁴C age. The simulation result shows that the main reactions controlling the geochemical evolution of confined water from the initial point to the final point in the groundwater flow path are the dissolution of plagioclase,horn blende,gypsum, Ca-Na exchange and the precipitation of carbonate minerals. The above reactions have little effect on the transfer time in the groundwater flow path. ¹⁴C correction result shows that deep groundwater in Yinchuan plain is paleogroundwater with ¹⁴C age more than 2 000 a except in the recharge area and the circulation rate is very slow and has low renewing capacity. Outside the depression cone of deep groundwater, the age of deep groundwater is becoming older along the groundwater flow path.However, in the depression cone,the age of deep groundwater is younger than the incoming water,which signifies that there is a close hydraulic relationship between deep groundwater and shallow groundwater.

Key words: Yinchuan plain, deep groundwater, correction of ¹⁴C age, inverse geochemical modeling