Underground renewal time and mixing of the main mineral waters of Tunisia: A multi-tracer study

Philippe Jean-Baptiste (1, 2) , Elise Fourré (1, 2) , Elyès Gaubi (3) , B. Minster (1, 2) , Luc Aquilina (4) , Thierry Labasque (4) , J.L. Michelot (5) , Marc Massault (5) , Abdallah Ben Mammou (3)

1 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
2 GLACCIOS - Glaces et Continents, Climats et Isotopes Stables
3 Laboratoire des Ressources Minérales et Environnement
4 GR - Géosciences Rennes
5 IDES - Interactions et dynamique des environnements de surface

Bottled waters are increasingly popular in Tunisia. Most of them come from groundwaters, thus raising the question of the long-term availability of the mineral groundwater resources. Water collected from production springs or wells of eleven mineral waters of Tunisia among the main commercial brands were analyzed for tritium (3H), helium-3, SF6, CFCs and carbon-14. Tracer-tracer plots indicate that all of the groundwaters of our data set are a mixture of modern rainwater with older groundwater flow waters that are beyond the time-scale of the transient tracers. 14C data suggest that the age of these old waters, which constitute the main water reservoir, is of the order of radiocarbon half-life or more. Most of the studied sites have groundwater renewal times in the range 50–150 years. For the sites where tracer concentrations are the most diluted by old waters, this value logically increase to several centuries.

Keywords: groundwater dating; environmental tracers; renewal time; Groundwater

Domains: Hydrology; Geochemistry

Philippe Jean-Baptiste, Elise Fourré, Elyès Gaubi, B. Minster, Luc Aquilina, et al.. Underground renewal time and mixing of the main mineral waters of Tunisia: A multi-tracer study. Applied Geochemistry, 2017, 85 (Part A), pp.10-18. ⟨10.1016/j.apgeochem.2017.08.006⟩. ⟨insu-01578508⟩