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| Titel |
The When, Where and Why of CO2 outgassing fluxes from an Alpine stream network |
| VerfasserIn |
Tom J. Battin, Jakob Schelker, Amber Ulseth, Gabriel Singer, Hannes Peter |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250105984
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| Publikation (Nr.) |
 EGU/EGU2015-5595.pdf |
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| Zusammenfassung |
| Headwater streams contribute substantially to CO2 outgassing to the atmosphere. However, regional and global estimates of CO2 outgassing fluxes from streams remain poorly constrained for several reasons. One of them relates to the temporal variability of streamwater pCO2 dynamics, which is rarely considered when extrapolating CO2 fluxes. A further limitation relates to our poor understanding of the gas transfer at the water/atmosphere interface in high-gradient streams. Elucidating these processes is key to understand the temporal and spatial dynamics of CO2 fluxes at the level of entire stream networks. Here we present data from a 3-years time series of diurnal measurements of pCO2 in the surface and hyporheic waters, and in the atmosphere of an Alpine headwater stream. Our results show how seasons, day-night shifts and fluctuations in discharge affect CO2 outgassing fluxes, and that nighttime outgassing was on average 1.8-times higher than day-time outgassing. Furthermore, based on repeated synoptic surveys in 148 streams in the same Alpine catchment we show how CO2 evasion rates change 1st and 5th-order streams. Our results suggest that small, first-order streams act as the predominant conduits for CO2 to the atmosphere in high-gradient streams, as they hold the highest potential for gas exchange combined with strong supersaturation of CO2. |
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