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| Titel |
Carbon export and transfer to depth across the Southern Ocean Great Calcite Belt |
| VerfasserIn |
S. Z. Rosengard, P. J. Lam, W. M. Balch, M. E. Auro, S. Pike, D. Drapeau, B. Bowler |
| 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 ; 12, no. 13 ; Nr. 12, no. 13 (2015-07-02), S.3953-3971 |
| Datensatznummer |
250118006
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| Publikation (Nr.) |
 copernicus.org/bg-12-3953-2015.pdf |
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| Zusammenfassung |
| Sequestration of carbon by the marine biological pump depends on the
processes that alter, remineralize, and preserve particulate organic carbon
(POC) during transit to the deep ocean. Here, we present data collected from
the Great Calcite Belt, a calcite-rich band across the Southern Ocean
surface, to compare the transformation of POC in the euphotic and
mesopelagic zones of the water column. The 234Th-derived export fluxes
and size-fractionated concentrations of POC, particulate inorganic carbon
(PIC), and biogenic silica (BSi) were measured from the upper 1000 m of 27
stations across the Atlantic and Indian sectors of the Great Calcite Belt.
POC export out of the euphotic zone was correlated with BSi export. PIC
export was not, but did correlate positively with POC flux transfer
efficiency. Moreover, regions of high BSi concentrations, which corresponded
to regions with proportionally larger particles, exhibited higher
attenuation of > 51 μm POC concentrations in the mesopelagic
zone. The interplay among POC size partitioning, mineral composition, and POC
attenuation suggests a more fundamental driver of POC transfer through both
depth regimes in the Great Calcite Belt. In particular, we argue that
diatom-rich communities produce large and labile POC aggregates, which not
only generate high export fluxes but also drive more remineralization in the
mesopelagic zone. We observe the opposite in communities with smaller
calcifying phytoplankton, such as coccolithophores. We hypothesize that
these differences are influenced by inherent differences in the lability of
POC exported by different phytoplankton communities. |
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