Mediterranean Peatland Water, Gas, and Soil content (Moltifau peatland, Corsica Island, France)

The present dataset is part of a research that aims to status the carbon storage function of a Mediterranean peatland in changing climate conditions. The scientific strategy relies on a seasonal geochemical survey sourcing the carbon origin in peatland water and interfaces with the atmosphere. This research on a representative Mediterranean peatland reveals the seasonality of hydrochemical processes and dissolved carbon inputs from primary production, organic matter oxidation, and time-changing recharge components within the catchment (atmospheric water, river water, shallow groundwater, deep groundwater). Mixing proportions of all recharge components known (Santoni et al., 2021), the study applies a “reverse” end-member mixing analysis to define the theoretical peat water δ13C-DIC value and compare it to the measured one. The model explains 65 % of the data, demonstrating the watershed's influence on peatland carbon content—such terrestrial carbon fluxes toward a peatland needed to be reported and quantified. Furthermore, in 35% of the cases, peatland processes such as primary production and organic matter oxidation drive the peat water's carbon content. Then, δ18O, δ2H, peat organic and inorganic properties, δ13C-TOC, and 13C-CO2 data demonstrate the dominance of primary production, evidencing the role of groundwater in CO2 production and carbon storage capacity of the Mediterranean peatland. This research proves the relevance of geochemistry and isotope hydrology tools to disentangle and rank peatland water and carbon processes. Thus, it constitutes an innovative methodology designed to provide the key elements to consider in order to set up a carbon balance diagnosis of peatlands worldwide. Overall, the present research reveals the necessity to consider the interactions between water and carbon cycle processes, with particular consideration for groundwater as a CO2 source at the peatland-atmosphere interface, to build better models for the future evolution of the global climate. (Publication in process)