Geochemical Evolution of Groundwater in Meng Xu Area, Gui Ping City, Southern China

Geochemical data on dissolved major constituents in groundwater samples from Meng Xu area reveal the main processes responsible for their geochemical evolution. Inverse models were developed using PHREEQC to elucidate the chemical reactions controlling water chemistry. The inverse modeling demonstrated that relatively few phases are required to derive water chemistry in the area. In a broad sense, the reactions responsible for the hydro chemical evolution in the area fall into four categories: dissolution of CO2; calcite dissolution; incongruent dolomite dissolution, dedolomization, ex-solution of CO2, and ion exchange. Apart from this process, there are others which influence the geochemical zoning of the system. The interaction of the CO2 with the carbonate matrix of the aquifer produces an increase in the alkalinity of the water.