Leakage of old carbon dioxide from a major river system in the Canadian Arctic

Dasari, S., Garnett, M. and Hilton, R. G. (2024) Leakage of old carbon dioxide from a major river system in the Canadian Arctic. PNAS Nexus, (doi: 10.1093/pnasnexus/pgae134) (Early Online Publication)

Abstract

The Canadian Arctic is warming at an unprecedented rate. Warming-induced permafrost thaw can lead to mobilization of aged carbon from stores in soils and rocks. Tracking the carbon pools supplied to surrounding river networks provides insight on pathways and processes of greenhouse gas release. Here, we investigated the dual-carbon isotopic characteristics of the dissolved inorganic carbon (DIC) pool in the main stem and tributaries of the Mackenzie River system. The radiocarbon (14C) activity of DIC shows export of ‘old’ carbon (2380±1040 14C years BP on average) occurred during summer in sampling years. The stable isotope composition of river DIC implicates degassing of aged carbon as CO2 from riverine tributaries during transport to the delta, however, information on potential drivers and fluxes are still lacking. Accounting for stable isotope fractionation during CO2 loss, we show that a large proportion of this aged carbon (60±10 %) may have been sourced from biospheric organic carbon oxidation, with other inputs from carbonate weathering pathways and atmospheric exchange. The findings highlight hydrologically connected waters as viable pathways for mobilization of aged carbon pools from Arctic permafrost soils.

• Item Type: Articles
• Additional Information: SD and RGH were funded by a European Research Council (ERC) Consolidator Grant (CoG 2020) “RIV-ESCAPE”, project number 101002563, to RGH. Radiocarbon measurements were part-funded by the UK Natural Environment Research Council (NERC), Radiocarbon Facility allocation number 1999.0416 to RGH.
• Status: Early Online Publication
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Garnett, Dr Mark
• Authors: Dasari, S., Garnett, M., and Hilton, R. G.
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre
• Journal Name: PNAS Nexus
• Publisher: Oxford University Press
• ISSN: 2752-6542
• ISSN (Online): 2752-6542
• Published Online: 29 March 2024
• Copyright Holders: Copyright © The Author(s) 2024
• First Published: First published in PNAS Nexus 2024
• Publisher Policy: Reproduced under a Creative Commons licence