The Role of Groundwater in CO2 Production and Carbon Storage in Mediterranean Peatlands: An Isotope Geochemistry Approach
2023
Santoni, S. | Garel, E. | Gillon, M. | Babic, M. | Spangenberg, J.E. | Bomou, B. | Sebag, D. | Adatte, T. | van Geldern, R. | Pasqualini, V. | Mattei, A. | Huneau, F. | Università di Corsica Pasquale Paoli [Université de Corse Pascal Paoli] ; Partenaires INRAE | Chimie et Biomasse, UMR-CNRS 6134 ; Sciences pour l'environnement (SPE) ; Université Pascal Paoli (UPP)-Centre National de la Recherche Scientifique (CNRS)-Université Pascal Paoli (UPP)-Centre National de la Recherche Scientifique (CNRS) | Environnement Méditerranéen et Modélisation des Agro-Hydrosystèmes (EMMAH) ; Avignon Université (AU)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE) | Institut des Dynamiques de la Surface Terrestre [Lausanne] (IDYST) ; Université de Lausanne = University of Lausanne (UNIL) | Institut des sciences de la terre [Lausanne] (ISTE) ; Université de Lausanne = University of Lausanne (UNIL) | IFP Energies nouvelles (IFPEN) ; IFP Energies nouvelles (IFPEN) | Friedrich-Alexander Universität Erlangen-Nürnberg = University of Erlangen-Nuremberg (FAU)
International audience
显示更多 [+] 显示较少 [-]英语. Peatlands are permanent wetlands recognized for ecosystem services such as biodiversity conservation and carbon storage capacity. Little information is available about their response to global change, the reason why most Earth system climate models consider a linear increase in the release of greenhouse gases (GHG), such as CO2, with increasing temperatures. Nevertheless, numerous studies suggest that an increase in the temperature may not imply a decrease in photosynthesis and carbon storage rates if water availability is sufficient, the latter being under the control of local hydrology mechanisms. Mediterranean peatlands well illustrate this fact. Since they are groundwater-dependent, they are hydrologically resilient to the strong seasonality of hydroclimatic conditions, especially during the summer drought. In the present study, we demonstrate that, even if such peatlands release CO2 into the atmosphere, they can maintain a carbon storage capacity. To this end, a geochemical study disentangles the origin and fate of carbon within a Mediterranean peatland at the watershed scale. Field parameters, major ions, dissolved organic and inorganic carbon content and associated δ13C values allow for characterizing the seasonality of hydrochemical mechanisms and carbon input from an alluvial aquifer (where rain, river, shallow, and deep groundwater flows are mixing) to the peatland. The inorganic and organic content of peat soil and δ13C values of total organic matter and CO2 complete the dataset, making it possible to provide arguments in favour of lower organic matter oxidation compared to primary production. Overall, this study highlights the groundwater role in the fluxes of CO2 at the peatland-atmosphere interface, and more broadly the need to understand the interactions between the water and carbon cycles to build better models of the future evolution of the global climate.
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