River Carbon Transport and Dynamics

The amount of carbon stored in the oceans and in soils greatly exceeds that present in the atmosphere. On timescales of < 10⁵ years atmospheric CO₂ levels are sensitive to variations of the “residence time” of carbon in these reservoirs. Predicting short-term variations in atmospheric CO₂  thus requires an understanding of controls on the storage time of OC within different reservoirs, but we currently have very limited knowledge of the factors that influence residence times of organic carbon in continental reservoirs, as well as how they respond to environmental changes. In order to constrain provenance and storage of biospheric carbon within terrestrial drainage basins we are tracing isotopic properties of marker compounds specific to vascular plants that are transported and discharged by different rivers systems (such as the Danube River, see picture above). This information is placed in the context of drainage basin properties and sediment and carbon fluxes to the oceans. Our research has revealed marked variations in 14C contents of biospheric carbon discharged by rivers, with ages reaching several thousand years for some high latitude drainage basins. These findings have implications not only for our understanding of the dynamics of terrestrial biospheric carbon transfer to the oceans, but also for interpretation of records of terrestrial paleoclimate from marine sediment archives.