University of Oulu

Rocher‐Ros, G., Harms, T. K., Sponseller, R. A., Väisänen, M., Mörth, C., & Giesler, R. (2020). Metabolism overrides photo‐oxidation in CO 2 dynamics of Arctic permafrost streams. Limnology and Oceanography. https://doi.org/10.1002/lno.11564

Metabolism overrides photo‐oxidation in CO₂ dynamics of Arctic permafrost streams

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Author: Rocher‐Ros, Gerard1; Harms, Tamara K.2; Sponseller, Ryan A.1;
Organizations: 1Climate Impacts Research Centre, Department of Ecology and Environmental Science, Umeå University, Abisko, Sweden
2Institute of Arctic Biology and Department of Biology & Wildlife, University of Alaska Fairbanks, Fairbanks, Alaska, USA
3Arctic Centre, University of Lapland, Rovaniemi, Finland
4Ecology and Genetics Research Unit, University of Oulu, Oulu, Finland
5Department of Geological Sciences, Stockholm University, Stockholm, Sweden
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.1 MB)
Persistent link: http://urn.fi/urn:nbn:fi-fe20201223102725
Language: English
Published: John Wiley & Sons, 2020
Publish Date: 2020-12-23
Description:

Abstract

Global warming is enhancing the mobilization of organic carbon (C) from Arctic soils into streams, where it can be mineralized to CO₂ and released to the atmosphere. Abiotic photo‐oxidation might drive C mineralization, but this process has not been quantitatively integrated with biological processes that also influence CO₂ dynamics in aquatic ecosystems. We measured CO₂ concentrations and the isotopic composition of dissolved inorganic C (δ¹³CDIC) at diel resolution in two Arctic streams, and coupled this with whole‐system metabolism estimates to assess the effect of biotic and abiotic processes on stream C dynamics. CO₂ concentrations consistently decreased from night to day, a pattern counter to the hypothesis that photo‐oxidation is the dominant source of CO₂. Instead, the observed decrease in CO₂ during daytime was explained by photosynthetic rates, which were strongly correlated with diurnal changes in δ¹³CDIC values. However, on days when modeled photosynthetic rates were near zero, there was still a significant diel change in δ¹³CDIC values, suggesting that metabolic estimates are partly masked by O₂ consumption from photo‐oxidation. Our results suggest that 6–12 mmol CO₂‐C m⁻² d⁻¹ may be generated from photo‐oxidation, a range that corresponds well to previous laboratory measurements. Moreover, ecosystem respiration rates were 10 times greater than published photo‐oxidation rates for these Arctic streams, and accounted for 33–80% of total CO₂ evasion. Our results suggest that metabolic activity is the dominant process for CO₂ production in Arctic streams. Thus, future aquatic CO₂ emissions may depend on how biotic processes respond to the ongoing environmental change.

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Series: Limnology and oceanography
ISSN: 0024-3590
ISSN-E: 0024-3590
ISSN-L: 0024-3590
DOI: 10.1002/lno.11564
OADOI: https://oadoi.org/10.1002/lno.11564
Type of Publication: A1 Journal article – refereed
Field of Science: 1172 Environmental sciences
Subjects:
Funding: This study was supported by the Swedish Research Council (VR; 2013‐5001), the Swedish Research Council for Environment, Agricultural Sciences, and Spatial Planning (FORMAS; 2014‐00970) and INTERACT (Grant Agreement No. 730938) and INTERACT Transnational Access to R.G.
EU Grant Number: (262693) INTERACT - International Network for Terrestrial Research and Monitoring in the Arctic
Dataset Reference: Supporting information:
  https://aslopubs.onlinelibrary.wiley.com/action/downloadSupplement?doi=10.1002%2Flno.11564&file=lno11564-sup-0001-Supinfo.zip
Copyright information: © 2020 The Authors. Limnology and Oceanography published by Wiley Periodicals LLC. on behalf of Association for the Sciences of Limnology and Oceanography. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
  https://creativecommons.org/licenses/by/4.0/