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 ...