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| Titel |
Pumping methane out of aquatic sediments – ebullition forcing mechanisms in an impounded river |
| VerfasserIn |
A. Maeck, H. Hofmann, A. Lorke |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 11 ; Nr. 11, no. 11 (2014-06-05), S.2925-2938 |
| Datensatznummer |
250117445
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| Publikation (Nr.) |
 copernicus.org/bg-11-2925-2014.pdf |
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| Zusammenfassung |
| Freshwater systems contribute
significantly to the global atmospheric methane budget. A large fraction of
the methane emitted from freshwaters is transported via ebullition. However,
due to its strong variability in space and time, accurate measurements of
ebullition rates are difficult; hence, the uncertainty regarding its
contribution to global budgets is large. Here, we analyze measurements made
by continuously recording automated bubble traps in an impounded river in
central Europe and investigate the mechanisms affecting the temporal dynamics
of bubble release from cohesive sediments. Our results show that the main
triggers of bubble release were pressure changes, originating from the
passage of ship lock-induced surges and ship passages. The response to
physical forcing was also affected by previous outgassing. Ebullition rates
varied strongly over all relevant timescales from minutes to days; therefore,
representative ebullition estimates could only be inferred with continuous
sampling over long periods. Since ebullition was found to be episodic,
short-term measurement periods of a few hours or days will likely
underestimate ebullition rates. Our results thus indicate that flux estimates
could be grossly underestimated (by up to ~50%) if the
correct temporal resolution is not used during data collection. |
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