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Article Dans Une Revue Geoderma Année : 2012

Controls on C-13 and C-14 variability in soil CO2

Résumé

C-14 dating of groundwater depends on the isotopic composition of both the solid carbonate and the soil CO2 and requires the use of C-14 age correction models. To better assess the variability of the C-14 activity of soil CO2 (A(14)C(soil-CO2)) and the delta C-13 of soil CO2 (delta C-13(soil-CO2)), which are two parameters used in C-14 age correction models, we studied the different processes involving carbon isotopes in the soil. The approach used experimental data from two sites in France (Fontainebleau sands and Astian sands) and a steady-state transport model. In most cases, the C-14 activity (A(14)C) of atmospheric CO2 is directly used in the C-14 age correction models as the A(14)C(soil-CO2). However, we demonstrate that since 1950, the evolution of the A(14)C(soil-CO2) reflects the competition between the fluxes of root-derived CO2 and organic matter-derived CO2. Therefore, the A(14)C(soil-CO2) must be used to date groundwater that is younger than 60 years old. Moreover, the delta C-13 of soil CO2 (delta C-13(soil-CO2)) showed large seasonal variations that must be taken into account in selecting the delta C-13(soil-CO2) for C-14 age correction models. (C) 2012 Elsevier B.V. All rights reserved.

Dates et versions

hal-01268263 , version 1 (04-02-2016)

Identifiants

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Marina Gillon, F. Barbecot, E. Gibert, Caroline Plain, J. -A. Corcho-Alvarado, et al.. Controls on C-13 and C-14 variability in soil CO2. Geoderma, 2012, 189, pp.431 - 441. ⟨10.1016/j.geoderma.2012.06.004⟩. ⟨hal-01268263⟩
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