EGU21-15020
https://doi.org/10.5194/egusphere-egu21-15020
EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Links between hydrological patterns and lateral carbon fluxes: a comparison between a wet and a drained site on a Siberian permafrost floodplain tundra

Sandra Raab1, Mathias Goeckede1, Jorien Vonk2, Anke Hildebrandt3,4, and Martin Heimann1,5
Sandra Raab et al.
  • 1Max Planck Institute for Biogeochemistry, Department of Biogeochemical Systems, Jena, Germany
  • 2Vrije Universiteit, Department of Earth Sciences, Faculty of Sciences, Amsterdam, The Netherlands
  • 3Friedrich-Schiller-University Jena, Institute of Geoscience, Jena, Germany
  • 4UFZ - Helmholtz Centre for Environmental Research, Department of Computational Hydrosystems, Leipzig, Germany
  • 5University of Helsinki, Institute for Atmospheric and Earth System Research (INAR), Finland

As a major reservoir for organic carbon, permafrost areas play a pivotal role in global climate change. Vertical carbon fluxes as well as lateral transport from land to groundwaters and surface waters towards the ocean are highly dependent on various abiotic and biotic factors. These include for example temperature, groundwater depth, or vegetation community. During summer months, when soils thaw and lateral carbon transport within suprapermafrost groundwater bodies and surface waters occurs, flow patterns and therefore carbon redistribution may differ significantly between dry and wet conditions. Since dry soil conditions are expected to become more frequent in the future, associated shifts in carbon transport patterns play an important role in quantifying the carbon input into the water body linked to permafrost degradation.

This study focuses on hydrological and carbon transport patterns within a floodplain tundra site near Chersky, Northeast Siberia. We compared a wet control site with a site affected by a drainage ring built in 2004 to study the effect of water availability on carbon production and transport. Water table depths at both sites were continuously monitored with a distributed sensor network over the summer seasons 2016-2020. At several locations, water samples were collected in 2016 and 2017 to determine organic carbon concentrations (DOC) as well as carbon isotopes (e.g. ∆14C-DOC). Suprapermafrost groundwater and surface water from the drainage ditch and the nearby Ambolikha river were included in the analysis.

Our results focus on the physical hydrological conditions as well as on DOC and ∆14C-DOC observations. The spatio-temporal dynamics of water table depth revealed systematic differences between control and drained sites. The drained area showed a stronger decrease in water tables towards peak summer season in July and stronger reactions to precipitation events. The control area responded less pronounced to short-term changes. At the drained site, the main groundwater flow direction was stable throughout the measurement period. The control site was characterized by a shift in water flow confluence depending on increasing and decreasing water levels. DOC and ∆14C-DOC data showed that the highest concentrations of organic carbon and oldest DOC can be found in late summer. DOC concentrations were higher at the drained site compared to the wet site. We will show that the distribution of dissolved carbon can be directly related to hydrological flow patterns, and that understanding of these redistribution processes is essential for interpreting the carbon budget in disturbed permafrost.

 

How to cite: Raab, S., Goeckede, M., Vonk, J., Hildebrandt, A., and Heimann, M.: Links between hydrological patterns and lateral carbon fluxes: a comparison between a wet and a drained site on a Siberian permafrost floodplain tundra, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15020, https://doi.org/10.5194/egusphere-egu21-15020, 2021.

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