The Hydrogeochemical Modeling for Total Hardness in Aquifer of Urban Area

The total hardness in aquifer often increased rapidly in urban area, and it may caused by the hydrogeochemistry. However it is not clear where the hydrogeochemistry happened in aquifer or in vadose zone. In this paper, mineral dissolution and cation exchange relevant to total hardness were simulated by the hydrogeochemical transport model in order to research the influences of the mineral dissolution and cation exchange in aquifer on chemical composition in groundwater system. The results showed that the contribution of calcite and dolomite dissolution to HCO₃^-, Ca²⁺ and Mg²⁺ of groundwater is less than 1 mg/L in a year, which revealed that the rapid increase of HCO₃^-, Ca²⁺ and Mg²⁺ of groundwater may derive from the mineral dissolution of vadose zone.