Contribution of time tracers (Mg 2+ , TOC, δ 13 C TDIC , NO 3 − ) to understand the role of the unsaturated zone: A case study-Karst aquifers in the Doubs valley, eastern France

Hélène Celle-Jeanton (1) , C. Emblanch (2) , J. Mudry (1) , A. Charmoille (3)

1 LCE - Laboratoire Chrono-environnement (UMR 6249)
2 EMMAH - Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes
3 INERIS - Institut National de l'Environnement Industriel et des Risques

[1] Time tracers (NO 3 À , TOC, d 13 C TDIC , Mg 2+) have been used to define the hydrodynamic behavior of a karst system: high values in NO 3 À and TOC reflect rapid infiltration and consequently a short residence time within the aquifer, whereas enriched d 13 C TDIC and high Mg 2+ are expected for ''old water''. 9 Springs and 5 boreholes have been sampled during three field campaigns in the Doubs valley karst aquifer: low water, flood and recession periods. A clear differentiation can be highlighted between boreholes, characterized by a long residence time, and springs that show a rapid infiltration. Considering only the springs values, it appears that TOC and d 13 C TDIC contents can easily be correlated to the sampling period. We show then the contribution of the unsaturated zone to the discharge during the low-water period, and the existence of reserves that seem badly connected to the drainage network, and that contribute poorly to the minimal flow.

Mots clés: INDEX TERMS: 1040 Geochemistry: Isotopic composition/chemistry; H; 1803 Hydrology: Anthropogenic effects Citation: Celle-Jeanton; 1875 Hydrology: Unsaturated zone; 1829 Hydrology: Groundwater hydrology; C Emblanch; J Mudry; and A Charmoille; Contribution of time tracers (Mg 2+; TOC; d 13

Domaines: Planète et Univers [physics]; Sciences de la Terre; Hydrologie

Hélène Celle-Jeanton, C. Emblanch, J. Mudry, A. Charmoille. Contribution of time tracers (Mg 2+ , TOC, δ 13 C TDIC , NO 3 − ) to understand the role of the unsaturated zone: A case study-Karst aquifers in the Doubs valley, eastern France. Geophysical Research Letters, 2003, 30 (6), ⟨10.1029/2002GL016781⟩. ⟨hal-02295162⟩