Titel
Gravel bars are sites of increased CO2 outgassing in stream corridors
Autor*in
Nico Trauth
Department of Hydrogeology, Helmholtz Centre for Environmental Research – UFZ
Christian Schmidt
Department of Hydrogeology, Helmholtz Centre for Environmental Research – UFZ
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Abstract
Streams are significant sources of CO2 to the atmosphere. Estimates of CO2 evasion fluxes (f CO2) from streams typically relate to the free flowing water but exclude geomorphological structures within the stream corridor. We found that gravel bars (GBs) are important sources of CO2 to the atmosphere, with on average more than twice as high f CO2 as those from the streamwater, affecting f CO2 at the level of entire headwater networks. Vertical temperature gradients resulting from the interplay between advective heat transfer and mixing with groundwater within GBs explained the observed variation in f CO2 from the GBs reasonably well. We propose that increased temperatures and their gradients within GBs exposed to solar radiation stimulate heterotrophic metabolism therein and facilitate the venting of CO2 from external sources (e.g. downwelling streamwater, groundwater) within GBs. Our study shows that GB f CO2 increased f CO2 from stream corridors by [median, (95% confidence interval)] 16.69%, (15.85–18.49%); 30.44%, (30.40–34.68%) and 2.92%, (2.90–3.0%), for 3rd, 4th and 5th order streams, respectively. These findings shed new light on regional estimates of f CO2 from streams, and are relevant given that streamwater thermal regimes change owing to global warming and human alteration of stream corridors.
Stichwort
Carbon cycleLimnology
Objekt-Typ
Sprache
Englisch [eng]
Persistent identifier
Erschienen in
Titel
Scientific Reports
Band
7
Publication
Springer Nature
Erscheinungsdatum
2017
Zugänglichkeit
Rechte
Rechteangabe
© The Author(s) 2017
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