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| Titel |
Long-term observation of particulate barium fluxes in the subtropical Northeast Atlantic (33°N, 22°W) |
| VerfasserIn |
Judith Stern, Olaf Dellwig, Joanna J. Waniek |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250140876
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| Publikation (Nr.) |
 EGU/EGU2017-4326.pdf |
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| Zusammenfassung |
| Particle flux material was collected with a sediment trap in 2000 m depth of the deep-sea
mooring Kiel 276. The mooring is located in the oligotrophic subtropical NE Atlantic (33˚
N, 22˚ W), which is influenced by the Azores Current and its associated front and lithogenic
particle inputs via atmospheric transport pathways.
Total barium fluxes and biogenic barium (Babio) fluxes between 2002 and 2008,
calculated on the basis of Ba amounts measured with ICP-OES (inductively coupled plasma
optical emission spectrometry), are demonstrated in this study. The behavior of (biogenic)
barium in the deep-sea is of great interest because it is used as a proxy for surface ocean
productivity. Nevertheless, formation and transport mechanisms of particulate Ba, especially
barite, in the oceans are still under debate. Especially, long-term Ba flux studies
demonstrating inter and intra annual variability are missing. To fill this gap we used
time-series measurements of Ba fluxes observed at Kiel 276 to demonstrate the variability
of particulate Ba formation and transport. Total Ba fluxes and Babio fluxes at the
mooring are characterized by flux pattern attributed to the behavior of the total
particle flux. The particle flux is highly variable with peak fluxes up to 365 mg m−2
d−1 during winter and early spring just after highest primary production (winter
bloom of coccolithophores) and maximum dust concentration in the atmosphere
occurred.
The Babioflux (up to 97 % of the total Ba flux) is influenced by productivity but also by
the position of the Azores Front leading to a clear reduced Babio flux from 2005 onwards
related to changes in shape and size of the catchment area of the sediment trap and reduced
productivity due to lower nutrient availability. We observed a close connection of Babio flux
and Ca flux results from incorporation of Ba in biogenic CaCO3 and from the formation of
aggregates including Ba-bearing particles like barite and biogenic CaCO3. The transport of
particulate Ba seems to be mainly driven by the formation of aggregates in the water column. |
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