1. Steps dominate gas evasion from a mountain headwater stream.
- Author
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Botter, Gianluca, Carozzani, Anna, Peruzzo, Paolo, and Durighetto, Nicola
- Subjects
RIVER channels ,CARBON dioxide ,GASES ,OUTGASSING - Abstract
Steps are dominant morphologic traits of high-energy streams, where climatically- and biogeochemically-relevant gases are processed, transported to downstream ecosystems or released into the atmosphere. Yet, capturing the imprint of the small-scale morphological complexity of channel forms on large-scale river outgassing represents a fundamental unresolved challenge. Here, we combine theoretical and experimental approaches to assess the contribution of localized steps to the gas evasion from river networks. The framework was applied to a representative, 1 km-long mountain reach in Italy, where carbon dioxide concentration drops across several steps and a reference segment without steps were measured under different hydrologic conditions. Our results indicate that local steps lead the reach-scale outgassing, especially for high and low discharges. These findings suggest that steps are key missing components of existing scaling laws used for the assessment of gas fluxes across water-air interfaces. Therefore, global evasion from rivers may differ substantially from previously reported estimates. Emissions from local steps dominate the CO2 evasion of mountain river networks, owing to the pronounced turbulence in correspondence of each plunging jet and the low spacing between steps typical of high energy streams. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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