As the critical importance of the land-ocean continuum's role in the global carbon balance is becoming ever more apparent, terrestrial carbon cycle models are now increasingly including an explicit representation of lateral carbon transport. However, the fluxes and mechanisms associated with lateral carbon transport through inland waters remain highly uncertain and poorly constrained. In this study, we investigate how burgeoning ¹³C and ¹⁴C datasets covering river and lake catchments in Switzerland help constrain a novel land-river-lake carbon cycle model. The measured samples comprise representative carbon phases and fractions in all major carbon reservoirs, and isotopic analysis allows us to effectively disentangle the different carbon sources in the receiving basins. Our datasets include ¹³C and ¹⁴C measurements of particulate and dissolved organic carbon, and dissolved inorganic carbon in river and lake water, dissolved phases of carbon in groundwater, and particulate, dissolved, and mineral-associated organic carbon in soils. These snapshots in time are supplemented with long-term isotopic records from lake sediments. The assimilation of these comprehensive and diverse datasets by our model exposes both the capabilities and limitations of high-density ¹³C and ¹⁴C data for the study of lateral carbon transport. We seek to further explore the potential of synergetic land-water sampling strategies for more effective model calibration, and ultimately to constrain the magnitude and sensitivity of lateral carbon fluxes as a component of the terrestrial carbon cycle.

Primary Presenter: Alexander Brunmayr, Imperial College London (asb219@ic.ac.uk)

Authors:

Alexander Brunmayr, Department of Physics, Imperial College London, London, United Kingdom  (asb219@ic.ac.uk)

Timo Rhyner, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland  (timo.rhyner@erdw.ethz.ch)

Margaux Moreno Duborgel, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland; WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland  (margaux.duborgel@wsl.ch)

Luisa Minich, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland; WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland  (luisa.minich@wsl.ch)

Margot White, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland  (margot.white@erdw.ethz.ch)

Benedict Mittelbach, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland  (benedict.mittelbach@erdw.ethz.ch)

Negar Haghipour, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland; Laboratory of Ion Beam Physics, Department of Physics, ETH Zurich, Zurich, Switzerland  (negar.haghipour@erdw.ethz.ch)

Nathalie Dubois, EAWAG Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland  (Nathalie.Dubois@eawag.ch)

Timothy Eglinton, Department of Earth Sciences, ETH Zurich, Zurich, Switzerland  (timothy.eglinton@erdw.ethz.ch)

Frank Hagedorn, WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland  (frank.hagedorn@wsl.ch)

Heather Graven, Department of Physics, Imperial College London, London, United Kingdom  (h.graven@imperial.ac.uk)