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| Titel |
Interannual variation in summer N2O concentration in the hypoxic region of the northern Gulf of Mexico, 1985–2007 |
| VerfasserIn |
I.-N. Kim, K. Lee, H. W. Bange, A. M. Macdonald |
| 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. 11 ; Nr. 10, no. 11 (2013-11-01), S.6783-6792 |
| Datensatznummer |
250085382
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| Publikation (Nr.) |
 copernicus.org/bg-10-6783-2013.pdf |
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| Zusammenfassung |
| Microbial nitrous oxide (N2O) production in the ocean is enhanced under
low-oxygen (O2) conditions. This is especially important in the context
of increasing hypoxia (i.e., oceanic zones with extremely reduced O2
concentrations). Here, we present a study on the interannual variation in
summertime nitrous oxide (N2O) concentrations in the bottom waters of
the northern Gulf of Mexico (nGOM), which is well-known as the site of the
second largest seasonally occurring hypoxic zone worldwide. To this end we
developed a simple model that computes bottom-water N2O concentrations
with a tri-linear ΔN2O/O2 relationship based on
water-column O2 concentrations, derived from summer (July)
Texas–Louisiana shelf-wide hydrographic data between 1985 and 2007. ΔN2O (i.e., excess N2O) was computed including nitrification and
denitrification as the major microbial production and consumption pathways of
N2O. The mean modeled bottom-water N2O concentration for July in
the nGOM was 14.5 ± 2.3 nmol L−1 (min:
11.0 ± 4.5 nmol L−1 in 2000 and max:
20.6 ± 11.3 nmol L−1 in 2002). The mean bottom-water N2O
concentrations were significantly correlated with the areal extent of hypoxia
in the nGOM. Our modeling analysis indicates that the nGOM is a persistent
summer source of N2O, and nitrification is dominating N2O
production in this region. Based on the ongoing increase in the areal extent
of hypoxia in the nGOM, we conclude that N2O production (and its
subsequent emissions) from this environmentally stressed region will probably
continue to increase into the future. |
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