Hazera J. auteur aut IRD Kowalewski I. auteur aut IRD Sebag D. auteur aut IRD Verrecchia E. auteur aut IRD Ravelojaona H. auteur aut IRD Chevallier Tiphaine auteur aut IRD text journalArticle eng text/pdf reformatted digital access Studying the soil organic and inorganic carbon (SOC and SIC) dynamics is essential to assess the carbon (C) sequestration potential of calcareous soils. Isotopic signatures (delta C-13) are used to assess the C origin of SOC or SIC. However, as measuring SOC and SIC contents, measuring delta C-13(SOC) and delta C-13(SIC) on a non-pretreated aliquot remains a challenge. Thermal analyses, like the Rock-Eval (RE) analysis, are promising to quantify SOC and SIC in a single analysis, but, to our knowledge, no development was conducted to assess delta C-13(SOC) and delta C-13(SIC). We coupled a RE device to an isotopic gas analyser (Picarro) to continuously measure delta C-13(CO2) and approach delta C-13(SOC) and delta C-13(SIC). We hypothesised that different carbonate mineralogies and/or crystal sizes in SIC involve fluctuations of the delta C-13(CO2). Two calcareous soils, a lithogenic (calcite) and a biogenic (snail shell) carbonate, and five calcite/shell mixes were analysed with the RE-Picarro setup. Two distinct delta C-13(CO2) values were obtained before and after 650 degrees C and were consistent with the delta C-13(SOC) and delta C-13(SIC) obtained by EA-IRMS. The fluctuations of delta C-13(CO2) above 650 degrees C were higher with calcite/shell mixes than with pure carbonates. A delta C-13(CO2) fluctuation > +/- 0.2 parts per thousand could be a pertinent indicator to detect mixes of carbonate with different delta C-13 in soils. The RE-Picarro setup is promising to assess SOC and SIC contents, delta C-13(SOC) and delta C-13(SIC) and detect mixes of carbonate with different origin on a non-pretreated aliquot. Development is needed (i) on more soil and carbonate samples and (ii) to improve the precision and accuracy of the RE-Picarro setup. specialized biogenic carbonate calcareous soils isotopic signature lithogenic carbonate Mediterranean soils FRANCE ZONE MEDITERRANEENNE 068 76 1 e70041 [5 p.] 2025 1351-0754 https://www.documentation.ird.fr/hor/fdi:010092695 10.1111/ejss.70041 1351-0754 [F B010092695] https://www.documentation.ird.fr/hor/fdi:010092695 https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2025-03/010092695.pdf IRD - Base Horizon / Pleins textes 2025-03-12 2026-06-12 fdi:010092695 fre