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Titel |
Nitrous oxide dynamics in low oxygen regions of the Pacific: insights from the MEMENTO database |
VerfasserIn |
L. M. Zamora, A. Oschlies, H. W. Bange, K. B. Huebert, J. D. Craig, A. Kock, C. R. Löscher |
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 ; 9, no. 12 ; Nr. 9, no. 12 (2012-12-06), S.5007-5022 |
Datensatznummer |
250007453
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Publikation (Nr.) |
copernicus.org/bg-9-5007-2012.pdf |
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Zusammenfassung |
The eastern tropical Pacific (ETP) is believed to be one of the largest
marine sources of the greenhouse gas nitrous oxide (N2O). Future
N2O emissions from the ETP are highly uncertain because oxygen minimum
zones are expected to expand, affecting both regional production and
consumption of N2O. Here we assess three primary uncertainties in how
N2O may respond to changing O2 levels: (1) the relationship between
N2O production and O2 (is it linear or exponential at low O2
concentrations?), (2) the cutoff point at which net N2O production
switches to net N2O consumption (uncertainties in this parameterisation
can lead to differences in model ETP N2O concentrations of more than
20%), and (3) the rate of net N2O consumption at low O2. Based
on the MEMENTO database, which is the largest N2O dataset currently
available, we find that N2O production in the ETP increases linearly
rather than exponentially with decreasing O2. Additionally, net
N2O consumption switches to net N2O production at ~ 10 μM O2,
a value in line with recent studies that suggest
consumption occurs on a larger scale than previously thought. N2O
consumption is on the order of 0.01–1 mmol N2O m−3 yr−1 in
the Peru-Chile Undercurrent. Based on these findings, it appears that recent
studies substantially overestimated N2O production in the ETP. In light
of expected deoxygenation and the higher than previously expected point at
which net N2O production switches to consumption, there is enough
uncertainty in future N2O production that even the sign of future
changes is still unclear. |
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