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| Titel |
Cryptic or day-to-day parts of the riverbed N cycle – new challenges for 15N |
| VerfasserIn |
Mark Trimmer, Liao Ouyang, Katrina Lansdown |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250136434
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| Publikation (Nr.) |
 EGU/EGU2016-17473.pdf |
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| Zusammenfassung |
| The discovery of anaerobic ammonium oxidation (anammox) not only changed our
understanding of the nitrogen cycle in aquatic ecosystems but it also undermined some of the
key 15N techniques used to study it. Reformulations of principle equations and the
development of new 15N2 and 15N2O techniques enabled the simultaneous quantification of
N2 production by anammox and denitrification in mainly soft, cohesive sediments where
redox gradients are clearly defined and solute exchanged governed by diffusion. At the heart
of the application of 15N, for the quantification of natural 14N cycling, is the key assumption
that the respective pools of 15N and 14N are evenly mixed and that both are cycled without
bias towards each other. Recent evidence, however, from a variety of aquatic ecosystems,
suggests that this may not be the case. For example, organic N may be oxidised directly to
N2 gas without ever mixing with the inorganic pool or inorganic intermediates
(e.g. nitrite) are ‘shunted’ internally and also fail to mix evenly with the applied
tracer pool. Our most recent work in permeable, oxic gravel riverbeds presents some
particular challenges to the application of 15N. In these systems, a tight coupling
between aerobic nitrification and anaerobic N2 production – in the presence of
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