Investigación hidrogeológica e hidroquímica de aguas subterráneas utilizando isótopos ambientales (18O, 2H, 3H, 14C) y trazadores químicos: un estudio de caso del acuífero intermedio Sfax, sureste de Túnez

Translated title of the contribution: Hydrogeological and hydrochemical investigation of groundwater using environmental isotopes (18O, 2H, 3H, 14C) and chemical tracers: a case study of the intermediate aquifer, Sfax, southeastern Tunisia

Rahma Ayadi, Rim Trabelsi, Kamel Zouari, Hakim Saibi, Ryuichi Itoi, Hafedh Khanfir

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)

Abstract

Major element concentrations and stable (δ18O and δ2H) and radiogenic (3H and 14C) isotopes in groundwater have proved useful tracers for understanding the geochemical processes that control groundwater mineralization and for identifying recharge sources in the semi-arid region of Sfax (southeastern Tunisia). Major-ion chemical data indicate that the origins of the salinity in the groundwater are the water–rock interactions, mainly the dissolution of evaporitic minerals, as well as the cation exchange with clay minerals. The δ18O and δ2H relationships suggest variations in groundwater recharge mechanisms. Strong evaporation during recharge with limited rapid water infiltration is evident in the groundwater of the intermediate aquifer. The mixing with old groundwater in some areas explains the low stable isotope values of some groundwater samples. Groundwaters from the intermediate aquifer are classified into two main water types: Ca-Na-SO4 and Ca-Na-Cl-SO4. The high nitrate concentrations suggest an anthropogenic source of nitrogen contamination caused by intensive agricultural activities in the area. The stable isotopic signatures reveal three water groups: non-evaporated waters that indicate recharge by recent infiltrated water; evaporated waters that are characterized by relatively enriched δ18O and δ2H contents; and mixed groundwater (old/recent) or ancient groundwater, characterized by their depleted isotopic composition. Tritium data support the existence of recent limited recharge; however, other low tritium values are indicative of pre-nuclear recharge and/or mixing between pre-nuclear and contemporaneous recharge. The carbon-14 activities indicate that the groundwaters were mostly recharged under different climatic conditions during the cooler periods of the late Pleistocene and Holocene.

Translated title of the contributionHydrogeological and hydrochemical investigation of groundwater using environmental isotopes (18O, 2H, 3H, 14C) and chemical tracers: a case study of the intermediate aquifer, Sfax, southeastern Tunisia
Original languageSpanish
Pages (from-to)983-1007
Number of pages25
JournalHydrogeology Journal
Volume26
Issue number4
DOIs
Publication statusPublished - Jun 1 2018

Keywords

  • Arid regions
  • Groundwater mineralization
  • Groundwater recharge
  • Stable/radiogenic isotopes
  • Tunisia

ASJC Scopus subject areas

  • Water Science and Technology
  • Earth and Planetary Sciences (miscellaneous)

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