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Environ Earth Sci (2014) 71:585599 DOI 10.1007/s12665-013-2754-8
THEMATIC ISSUE
Using non-conservative tracers to characterise karstication processes in the Merinos-Colorado-Carrasco carbonate aquifer system (southern Spain)
J. A. Barber B. Andreo C. Almeida
Received: 30 July 2013 / Accepted: 21 August 2013 / Published online: 7 September 2013 Springer-Verlag Berlin Heidelberg 2013
Abstract The systematic sampling of the chemical composition of the groundwater from ve karst springs (including an overow spring) and one outowing borehole have permitted to determine distinctive chemical changes in the waters that reect the geochemical processes occurring in a carbonate aquifer system from southern Spain. The analysis of the dissolution parameters revealed that geochemical evolution of the karst waters basically depends on the availability of the minerals forming aquifer rocks and the residence time within the aquifers. In the three proposed scenarios in the aquifers, which include the preferential ow routines, the more important geochemical processes taking place during the groundwater ow from the recharge to the discharge zones are: CO2 dissolution and exsolution (outgassing), calcite net dissolution, calcite and dolomite sequential dissolution, gypsum/anhydrite and halite dissolution, de-dolomitization and calcite precipitation. A detailed analysis of the hydrochemical data set, saturation indices of the minerals and partial pressure of CO2 in the waters joined to the application of geochemical modelling methods allowed the elaboration of a hydro-geochemical model of the studied aquifers. The developed approach contributes to a better understanding of the karstication processes and the hydrogeological
functioning of carbonate aquifers, the latter being a crucial aspect for the suitable management of the water resources.
Keywords Carbonate (karst) aquifer
Hydrochemistry Chemical processes
Geochemical modelling Conceptual model
Introduction
The karstication in carbonate aquifers is conditioned by the chemical and mineral composition of the main (aquifer) lithologies, the predominant geochemical processes, the residence time of the water and by other intrinsic factors that dene the hydrogeological functioning of the system (Ford and Williams 2007). The latter can be addressed by different research methods: hydrodynamic (Mangin 1975), hydrothermal (Anderson 2005), hydrochemistry (Shuster and White 1971; Bakalowicz 1979; Mudry 1987) and also environmental isotopes (Bakalowicz et al. 1974; Perrin et al. 2003).
The behaviour of a karstic aquifer is based on two important qualitative parameters, such as the ow type and the degree of karstication. The analysis of...