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| Titel |
Marine denitrification rates determined from a global 3-D inverse model |
| VerfasserIn |
T. DeVries, C. Deutsch, P. A. Rafter, F. Primeau |
| 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 ; 10, no. 4 ; Nr. 10, no. 4 (2013-04-15), S.2481-2496 |
| Datensatznummer |
250018198
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| Publikation (Nr.) |
 copernicus.org/bg-10-2481-2013.pdf |
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| Zusammenfassung |
| A major impediment to understanding long-term changes in the marine nitrogen
(N) cycle is the persistent uncertainty about the rates, distribution, and
sensitivity of its largest fluxes in the modern ocean. We use a global ocean
circulation model to obtain the first 3-D estimate of marine denitrification
rates that is maximally consistent with available observations of nitrate
deficits and the nitrogen isotopic ratio of oceanic nitrate. We find a global
rate of marine denitrification in suboxic waters and sediments of
120–240 Tg N yr−1, which is lower than many other recent
estimates. The difference stems from the ability to represent the 3-D spatial
structure of suboxic zones, where denitrification rates of
50–77 Tg N yr−1 result in up to 50% depletion of
nitrate. This depletion reduces the effect of local isotopic enrichment on
the rest of the ocean, allowing the N isotope ratio of oceanic nitrate to be
achieved with a sedimentary denitrification rate about 1.3–2.3 times that of
suboxic zones. This balance of N losses between sediments and suboxic zones
is shown to obey a simple relationship between isotope fractionation and the
degree of nitrate consumption in the core of the suboxic zones. The global
denitrification rates derived here suggest that the marine nitrogen budget is
likely close to balanced. |
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