Poster De Conférence Année : 2025

Specific carbon fluxes in rivers from long-term monitoring

Camille Crapart
Camille Bouchez
Yann Copard
  • Fonction : Auteur
Quentin Tenailleau

Résumé

The transfer of carbon from land to rivers and ocean is a key part of the carbon cycle, yet it is poorly quantified. The amount of carbon transported by inland waters is comparable with the amount of carbon stored on land, but large variations exist depending on the climatic, lithologic and land-use characteristics of watersheds. In the framework of the Carbonium project, a target project in the FairCarboN national project, we focus on bridging this gap. In a first stage, we aim at quantifying carbon fluxes in rivers, both dissolved and particulate as well as organic and inorganic. In a second stage, these fluxes will be related to river and watershed characteristic such as the maximum discharge, average slope, land use, or lithologic features. A data base comprising for now data from 30 sites belonging to the French research networks OZCAR (Observatoires de la Zone Critique: Applications et Recherche) and RZA (Réseau Zones Ateliers). These sites exhibit long term data sets of liquid discharge, suspended sediment concentrations (SSC) and Carbon concentrations covering a large diversity of lithologies, land use, and meteorological forcing. Most of them are located on the metropolitan territory of France, but data from overseas and foreign countries is also available. Dissolved organic carbon (DOC) vary from very low concentrations (close to 0.1 mgC/L) to concentrations up to 73 mgC/L in tropical rivers. Particulate organic carbon (POC) concentrations are mostly comprised between 0.5 and 22 mgC/L, with occasional events resulting in concentrations as high as 500 mgC/L in the Gier River, a tributary of the Rhône, or the Isère River.This represents carbon contents from 2 to 15%, occasionaly much higher. Specific carbon fluxes vary from 10-2 kg/km2/year in the Bernadouze or in the Gardon to 4x103 kg/km2/year, in the Galabre or in Isère Rivers, with larger rivers such as the Rhône displaying fluxes around 1x103 kg/km2/year. However, estimations of fluxes are subject to high uncertainty related to the availability of data, its frequency and the proxies used to obtain continuous temporal series of DOC and POC concentrations. As a matter of fact, measured parameters do not often include the concentration of DOC and POC. However, each river has a distinct relationship between SSC or turbidity, and POC; while the DOC concentration can be linked to the water flow. The second step of the analysis is therefore to test and select an appropriate method to establish these relationships when low frequency data is available. For example, the field stations of the Rhône River in Arles (south of France), the Coët-Dan River in Naizin (Brittany), or the Mule Hole observatory in India, are suitable candidates because they dispose of high frequency records of flow, turbidity, SSC, and carbon concentrations. In addition, appropriate method of fluxes computation must be chosen depending on the frequency of data measurement.

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Dates et versions

hal-05074842 , version 1 (11-09-2025)

Identifiants

  • HAL Id : hal-05074842 , version 1

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Camille Crapart, Stéphane Audry, Camille Bouchez, Julien Bouchez, Yann Copard, et al.. Specific carbon fluxes in rivers from long-term monitoring. Advancing Critical Zone science, 3ème Conférence internationale OZCAR TERENO 2025, Sep 2025, Paris, France. , 2025. ⟨hal-05074842⟩
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