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| Titel |
Particle fluxes in the deep Eastern Mediterranean basins: the role of ocean vertical velocities |
| VerfasserIn |
L. Patara, N. Pinardi, C. Corselli, E. Malinverno, M. Tonani, R. Santoleri, S. Masina |
| 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 ; 6, no. 3 ; Nr. 6, no. 3 (2009-03-06), S.333-348 |
| Datensatznummer |
250003528
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| Publikation (Nr.) |
 copernicus.org/bg-6-333-2009.pdf |
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| Zusammenfassung |
| This paper analyzes the relationship between deep sedimentary fluxes and
ocean current vertical velocities in an offshore area of the Ionian Sea, the
deepest basin of the Eastern Mediterranean Sea. Sediment trap data are
collected at 500 m and 2800 m depth in two successive moorings covering the
period September 1999–May 2001. A tight coupling is observed between the
upper and deep traps and the estimated particle sinking rates are more than
200 m day−1. The current vertical velocity field is computed from a
1/16°×1/16° Ocean General Circulation Model simulation and
from the wind stress curl. Current vertical velocities are larger and more
variable than Ekman vertical velocities, yet the general patterns are alike.
Current vertical velocities are generally smaller than 1 m day−1: we
therefore exclude a direct effect of downward velocities in determining high
sedimentation rates. However we find that upward velocities in the
subsurface layers of the water column are positively correlated with deep
particle fluxes. We thus hypothesize that upwelling would produce an
increase in upper ocean nutrient levels – thus stimulating primary
production and grazing – a few weeks before an enhanced vertical flux is
found in the sediment traps. High particle sedimentation rates may be
attained by means of rapidly sinking fecal pellets produced by gelatinous
macro-zooplankton. Other sedimentation mechanisms, such as dust deposition,
are also considered in explaining large pulses of deep particle fluxes. The
fast sinking rates estimated in this study might be an evidence of the
efficiency of the biological pump in sequestering organic carbon from the
surface layers of the deep Eastern Mediterranean basins. |
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