Effect of Cave Ventilation on Karst Water Chemographs

Abstract

The data briefly presented in this paper indicate that the degree of ventilation of underground flow paths, inducing more or less degassing of the CO2 dissolved in water, can induce a significant variation in the water mineralization of a karst spring. The presented data also provide indications about further conditions controlling time variations of carbonate dissolution parameters: (1) variations in the mixing ratio of two or several waters (from distinct subcatchment areas) with distinct chemistry; (2) land use with distinct soils (i.e. pCO2) in the catchment area, which is also often related to the elevation of the various parts of the catchment area; (3) localized and quick infiltration vs diffuse and slow infiltration through soils. It must be mentioned here that both concentrations and fluxes of CO2 within all parts of karst systems must be considered in order to understand water chemographs. Both are mainly controlled by soil CO2 production and by water-recharge flux. Further models and dedicated field data are required to better quantify CO2 concentration and fluxes in karst systems.