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| Titel |
Effects of dust deposition on iron cycle in the surface Mediterranean Sea: results from a mesocosm seeding experiment |
| VerfasserIn |
T. Wagener, C. Guieu, N. Leblond |
| 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 ; 7, no. 11 ; Nr. 7, no. 11 (2010-11-23), S.3769-3781 |
| Datensatznummer |
250005069
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| Publikation (Nr.) |
 copernicus.org/bg-7-3769-2010.pdf |
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| Zusammenfassung |
| Soil dust deposition is recognized as a major source of iron to the open
ocean at global and regional scales. However, the processes that control the
speciation and cycle of iron in the surface ocean after dust deposition are
poorly documented mainly due to the logistical difficulties to investigate
in-situ, natural dust events. The development of clean mesocosms in the frame of the
DUNE project (a DUst experiment in a low Nutrient low chlorophyll Ecosystem)
was a unique opportunity to investigate these processes at the unexplored
scale of one dust deposition event. During the DUNE-1-P mesocosm seeding
experiment, iron stocks (dissolved and particulate concentrations in the
water column) and fluxes (export of particulate iron in sediment traps) were
followed during 8 days after an artificial dust seeding mimicking a wet
deposition of 10 g m−2. The addition of dust at the surface of the
mesocosms was immediately followed by a decrease of dissolved iron [dFe]
concentration in the 0–10 m water column. This decrease was likely due to
dFe scavenging on settling dust particles and mineral organic aggregates.
The scavenging ratio of dissolved iron on dust particles averaged 0.37 ± 0.12 nmol mg−1. Batch dissolution experiments conducted in parallel
to the mesocosm experiment showed a increase (up to 600%) in dust iron
dissolution capacity in dust-fertilized waters compared to control
conditions. This study gives evidences of complex and unexpected effects of
dust deposition on surface ocean biogeochemistry: (1) large dust deposition
events may be a sink for surface ocean dissolved iron and (2) successive
dust deposition events may induce different biogeochemical responses in the
surface ocean. |
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