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Sammanfattning

Carbon dioxide (CO2) evasion and downstream export of carbon (C) from headwater streams represent important fluxes in the global C cycle. Yet, these fluxes are generally studied in isolation, leaving gaps in the understanding of the overall role of streams in the C cycle. In this study, we carried out high resolution measurements of dissolved inorganic and organic C to estimate CO2 evasion and C export along a 400 m reach of a boreal headwater stream to assess the magnitude and control of the C evasion:export ratio. Higher downstream C export (3.1-74.0 kg C d-1) compared to CO2 evasion rates (0.53-2.56 kg C d-1) for the full stream network over the open water season resulted in an average C evasion:export ratio of 0.23, which corresponds to a 17% loss of C entering the stream through CO2 evasion. The temporal variation in C evasion:export ratios (0.03-0.60) was mainly driven by stream discharge, largely through its strong influence on downstream C export. Further, CO2 evasion showed high spatial variability, and we demonstrate that using only data of a subset of the stream reach would lead to a wide range in the overall C evasion:export ratios upscaled to the whole stream network. Resolving the processes controlling spatial and temporal variation in C fluxes and understanding the importance of discharge for the fate of C routed through streams is crucial for predicting the terrestrial C sink capacity at high latitudes under a changing climate.

Nyckelord

inland water; carbon cycle; carbon dioxide emission; hydrology; dissolved carbon; runoff

Publicerad i

Journal of Geophysical Research: Biogeosciences
2026, volym: 131, nummer: 2, artikelnummer: e2024JG008671
Utgivare: AMER GEOPHYSICAL UNION

SLU författare

UKÄ forskningsämne

Oceanografi, hydrologi, vattenresurser

Publikationens identifierare

  • DOI: https://doi.org/10.1029/2024JG008671

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/146498