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| Titel |
Quantification of the lithogenic carbon pump following a simulated dust-deposition event in large mesocosms |
| VerfasserIn |
M. Bressac, C. Guieu, D. Doxaran, F. Bourrin, K. Desboeufs, N. Leblond, C. Ridame |
| 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 ; 11, no. 4 ; Nr. 11, no. 4 (2014-02-21), S.1007-1020 |
| Datensatznummer |
250117238
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| Publikation (Nr.) |
 copernicus.org/bg-11-1007-2014.pdf |
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| Zusammenfassung |
| Lithogenic particles, such as desert dust, have been postulated to influence
particulate organic carbon (POC) export to the deep ocean by acting as
mineral ballasts. However, an accurate understanding and quantification of
the POC–dust association that occurs within the upper ocean is required in
order to refine the "ballast hypothesis". In the framework of the DUNE (a
DUst experiment in a low-Nutrient, low-chlorophyll Ecosystem) project, two
artificial seedings were performed seven days apart within large mesocosms.
A suite of optical and biogeochemical measurements were used to quantify
surface POC export following simulated dust events within a low-nutrient,
low-chlorophyll ecosystem. The two successive seedings led to a 2.3–6.7-fold
higher POC flux than the POC flux observed in controlled
mesocosms. A simple linear regression analysis revealed that the lithogenic
fluxes explained more than 85% of the variance in POC fluxes. On the
scale of a dust-deposition event, we estimated that 42–50% of POC fluxes
were strictly associated with lithogenic particles (through aggregation and
most probably sorption processes). Lithogenic ballasting also likely
impacted the remaining POC fraction which resulted from the fertilization
effect. The observations support the "ballast hypothesis" and provide a
quantitative estimation of the surface POC export abiotically triggered by
dust deposition. In this work, we demonstrate that the strength of such a
"lithogenic carbon pump" depends on the biogeochemical conditions of the
water column at the time of deposition. Based on these observations, we
suggest that this lithogenic carbon pump could represent a major
component of the biological pump in oceanic areas subjected to intense
atmospheric forcing. |
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