Preprints
https://doi.org/10.5194/bg-2021-150
https://doi.org/10.5194/bg-2021-150

  02 Jul 2021

02 Jul 2021

Review status: this preprint is currently under review for the journal BG.

Low biodegradability of particulate organic carbon mobilized from thaw slumps on the Peel Plateau, NT, and possible chemosynthesis and sorption effects

Sarah Shakil1, Suzanne Tank1, Jorien Vonk2, and Scott Zolkos1,a Sarah Shakil et al.
  • 1Department of Biological Sciences, University of Alberta, Edmonton, Canada
  • 2Department of Earth Sciences, Vrije Universiteit, Amsterdam, The Netherlands
  • acurrent address: John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA

Abstract. Upon thaw, permafrost carbon entering streams may be mineralized into CO2 or re-sequestered into sediments. The balance between these processes is an important uncertainty in the permafrost-carbon-climate feedback. Warming and wetting in the western Canadian Arctic are accelerating thaw-driven mass wasting by permafrost thaw slumps, increasing particulate organic carbon (POC) delivered to headwater streams by orders of magnitude. Using aerobic incubations of POC from streams affected by thaw slumps we find that slump-mobilized POC undergoes minimal (~4 %) oxidation over a 1-month period and may be predominantly destined for sediment deposition. Mobilization of mineral-rich tills in this region may also protect carbon from mineralization via adsorption to minerals and promote inorganic carbon sequestration via chemolithoautotrophic processes. Region-specific assessments of permafrost carbon fates and inquiries beyond organic carbon decomposition are needed to constrain drivers of carbon cycling and climate feedbacks within stream networks affected by permafrost thaw.

Sarah Shakil et al.

Status: open (until 16 Aug 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Sarah Shakil et al.

Sarah Shakil et al.

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Short summary
Permafrost thaw-driven landslides in the western Arctic are increasing organic carbon delivered to headwaters of drainage networks in the western Canadian Arctic by orders of magnitude. Through a series of laboratory experiments, we show that less than 10 % of this organic carbon is likely to be mineralized to greenhouse gases during transport in these networks. Rather most of the organic carbon is likely destined for burial and sequestration for centuries to millennia.
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