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ToolsCastro-Morales, K., Canning, A., Arzberger, S., Kaiser, J., Overholt, W. A., Sellmaier, A., Khodabakhshi, N., Redlich, S., Marca, A., Kolle, O., Göckede, M., Wichard, T., Küsel, K., Körtzinger, A. and Zimov, N. (2025) Aquatic productivity signals in the Kolyma River (northeastern Siberia) from O2/Ar ratios and O2 triple isotopologues. Journal of Geophysical Research: Biogeosciences, 130 (12). ISSN 2169-8953
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Abstract
Arctic rivers are intricate water networks that chemically and biologically process carbon before releasing it as carbon dioxide (CO2) into the atmosphere or carrying it to the ocean. Primary producers use inorganic carbon to build biomass at the base of the trophic chain. Little is known about how biogeochemical properties in Arctic rivers adapt to climate warming and changes in hydrology. To quantify net and gross biological productivity, we measured the dissolved oxygen-to-argon (O2/Ar) ratios and O 2 triple isotopologues composition in the river Kolyma and in its tributary Ambolikha during late freshet (June) and low-flow conditions (August) in 2019. We found that hydrological factors restricted river productivity. The river system released CO2 into the atmosphere in June and August, however August emissions were only 6% of late freshet emissions. In June, higher river flow and turbidity restricted river production, but in August, lower flows allowed more light penetration and a phytoplankton bloom at the tributary-main Kolyma channel confluence. CO2 emissions per area during June and August accounted for 5 ± 11% of the gross carbon uptake estimated during a bloom event. Thus, in-stream metabolism can exceed riverine CO2 emissions under certain flow and light conditions. Arctic climate change may promote biological productivity in particular locations along with changes in dissolved organic matter signature and microbiome, and contribute to Arctic river carbon budgets as flow slows during prolongued open water periods.
| Item Type: | Article |
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| Additional Information: | Data Availability Statement: The hydrochemical continuous and discrete data presented in this study are available at the Zenodo EU repository via https://doi.org/10.5281/zenodo.15229557 under the license Creative Commons Attribution 4.0 Internations (Castro-Morales, 2025). Funding information: This work was conceived and developed for the project PROPERAQUA funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) 396657413 led by K.C-M. The EU project C-CASCADES ITN (643052) funded A.C. and A.K., as well as the MOSES program of the Helmholtz Association. T.W. and S.R. were funded by the DFG in the framework of the priority program (SPP 1158) “Antarctic Research with comparative investigations in Arctic ice areas” (424256657). M.G. and O.K. were supported through funding by the EU projects INTAROS (727890) and Nunataryuk (773421), and the German Ministry of Education and Research (KoPf project, Grant 03F0764D). K.K. and W.A.O were supported by the Collaborative Research Centre 1076 AquaDiva (CRC AquaDiva) funded by DFG (218627073). J.K. was supported from the UK Research and Innovation (UKRI) Grant 10040851, linked to Grant 101056921 of the European Union's Horizon EUROPE research and innovation program. |
| Uncontrolled Keywords: | arctic rivers,carbon cycling,carbon dioxide,oxygen,permafrost,primary production,water science and technology,forestry,aquatic science,soil science,palaeontology,ecology,atmospheric science ,/dk/atira/pure/subjectarea/asjc/2300/2312 |
| Faculty \ School: | Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA Faculty of Science |
| UEA Research Groups: | Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 16 Dec 2025 15:30 |
| Last Modified: | 17 Dec 2025 07:30 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/101426 |
| DOI: | 10.1029/2025JG009415 |
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