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| Titel |
Downward fluxes of sinking particulate matter in the deep Ionian Sea (NESTOR site), eastern Mediterranean: seasonal and interannual variability |
| VerfasserIn |
S. Stavrakakis, A. Gogou, E. Krasakopoulou, A. P. Karageorgis, H. Kontoyiannis, G. Rousakis, D. Velaoras, L. Perivoliotis, G. Kambouri, I. Stavrakaki, V. Lykousis |
| 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 (2013-11-12), S.7235-7254 |
| Datensatznummer |
250085411
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| Publikation (Nr.) |
 copernicus.org/bg-10-7235-2013.pdf |
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| Zusammenfassung |
| In order to assess seasonal and interannual variability in the export of
particulate matter and its main constituents, sediment traps were deployed at
five successive depths from February 2006 to March 2010 in the deepest basin
of the Mediterranean (SE Ionian Sea, NESTOR site). The average total mass
fluxes were 66, 58, 54, 34, and 52 mg m−2 d−1, at 700, 1200,
2000, 3200, and 4300 m, respectively. The temporal variations of the mass
flux showed similar seasonal signal at all sampling depths with higher values
in spring–summer and lower in autumn–winter. Changes in the main
constituents of the mass flux (organic carbon, carbonates, opal, and
lithogenic matter) largely followed the same temporal variability with total
mass flux, revealing mechanisms of rapid vertical (top-down) transport from
700 m down to 4300 m depth. Lateral inputs at the deepest trap are probably
of importance, attributed to the influence of the deep Adriatic water,
characterized by relatively higher turbidity than overlying water masses. Two
major processes seem to control the seasonal mass flux variability: (a)
primary productivity at the euphotic zone; and (b) episodic dust input
events. Primary productivity shows two maxima during late winter/early spring
and late spring/summer, as witnessed by the organic carbon, carbonate, and
opal fluxes in the mesopelagic and bathypelagic layers, whereas the influence
of dust inputs is evidenced by enhanced lithogenic fluxes occurring during
spring and summer. The interannual variability generally shows a gradual
increase of fluxes during the time frame of the experiment. Both seasonal and
interannual variability of mass flux are associated with variations in the
intensity and position of the neighboring Pelops anticyclonic gyre, which
appears to affect the upwelling of intermediate, nutrient-rich waters and
subsequently the surface productivity. Combination of estimated satellite and
algorithm-generated primary production data for the Ionian Sea, calculated
POC fluxes out of the euphotic layer and POC fluxes measured by sediment
traps at the mesopelagic and bathypelagic layers of NESTOR site during our
4 yr experiment, reveal that only a small portion of primary production
(0.46%) reaches at 3200 m, corresponding to a mean annual carbon export
of 1.12 g C m−2 yr−1. |
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