Interpreting CO2-SIc relationship to estimate CO2 baseline in limestone aquifers

Nicolas Peyraube (1, 2) , R. Lastennet (2) , A. Denis (2) , P. Malaurent (2) , J.D. Villanueva (3)

1 ISTO - Institut des Sciences de la Terre d'Orléans - UMR7327
2 I2M - Institut de Mécanique et d'Ingénierie de Bordeaux
3 SESAM

Saturation index with respect to calcite (SIc) and equilibrium CO2 partial pressure are important parameters to study groundwater in limestone aquifers. Aside from their use in time series, CO2 and SIc are used to estimate the baseline of CO2 in the vadose zone. The objective of this paper is to present conceptual examples on the use of the CO2-SIc relationship to have new information from usual parameters. Case study was considered as an example of use from Cussac site, a limestone aquifer in southwest of France. The result showed that CO2 baseline in unsaturated zone is found close to 25,000 ± 1,000 ppm.

Keywords: CO2 baseline Carbonate rock Unsaturated zone

Domains: Continental interfaces, environment; Global Changes

Nicolas Peyraube, R. Lastennet, A. Denis, P. Malaurent, J.D. Villanueva. Interpreting CO2-SIc relationship to estimate CO2 baseline in limestone aquifers. Environmental Earth Sciences, 2015, 1, pp.19-26. ⟨10.1007/s12665-014-3316-4⟩. ⟨insu-01021139⟩