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| Titel |
Spatial and temporal variations in dissolved and particulate organic nitrogen in the equatorial Pacific: biological and physical influences |
| VerfasserIn |
X. J. Wang, R. Borgne, R. Murtugudde, A. J. Busalacchi, M. Behrenfeld |
| 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 ; 5, no. 6 ; Nr. 5, no. 6 (2008-12-11), S.1705-1721 |
| Datensatznummer |
250002935
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| Publikation (Nr.) |
 copernicus.org/bg-5-1705-2008.pdf |
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| Zusammenfassung |
| To quote Libby and Wheeler (1997), "we have only a cursory knowledge of the
distributions of dissolved and particulate organic nitrogen" in the
equatorial Pacific. A decade later, we are still in need of spatial and
temporal analyses of these organic nitrogen pools. To address this issue, we
employ a basin scale physical-biogeochemical model to study the spatial and
temporal variations of dissolved organic nitrogen (DON) and particulate
organic nitrogen (PON). The model is able to reproduce many observed
features of nitrate, ammonium, DON and PON in the central and eastern
equatorial Pacific, including the asymmetries of nitrate and ammonium, and
the meridional distributions of DON and PON. Modeled DON (5–8 mmol m−3)
shows small zonal and meridional variations in the mixed layer whereas
modeled PON (0.4–1.5 mmol m−3) shows considerable spatial variability.
While there is a moderate seasonality in both DON and PON in the mixed
layer, there is a much weaker interannual variability in DON than in PON.
The interannual variability in PON is largely associated with the El
Niño/Southern Oscillation (ENSO) phenomenon, showing high values during
cold ENSO phase but low values during warm ENSO phase. Overall, DON and PON
have significant positive correlations with phytoplankton and zooplankton in
the mixed layer, indicting the biological regulation on distribution of
organic nitrogen. However, the relationships with phytoplankton and
zooplankton are much weaker for DON (r=0.18–0.71) than for PON (r=0.25–0.97).
Such a difference is ascribed to a relatively larger degree of
physical control (e.g., upwelling of low-organic-N deep waters into the
surface) on DON than PON. |
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