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| Titel |
Impact of changes in river fluxes of silica on the global marine silicon cycle: a model comparison |
| VerfasserIn |
C. Y. Bernard, G. G. Laruelle, C. P. Slomp, C. Heinze |
| 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. 2 ; Nr. 7, no. 2 (2010-02-02), S.441-453 |
| Datensatznummer |
250004481
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| Publikation (Nr.) |
 copernicus.org/bg-7-441-2010.pdf |
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| Zusammenfassung |
| The availability of dissolved silica (Si) in the ocean provides a major
control on the growth of siliceous phytoplankton. Diatoms in particular
account for a large proportion of oceanic primary production. The original
source of the silica is rock weathering, followed by transport of dissolved
and biogenic silica to the coastal zone. This model study aims at assessing
the sensitivity of the global marine silicon cycle to variations in the
river input of silica on timescales ranging from several centuries to
millennia. We compare the performance of a box model for the marine silicon
cycle to that of a global biogeochemical ocean general circulation model
(HAMOCC2 and 5). Results indicate that the average global ocean response to
changes in river input of silica is comparable in the models on time scales
up to 150 kyrs. While the trends in export production and opal burial are
the same, the box model shows a delayed response to the imposed
perturbations compared to the general circulation model. Results of both
models confirm the important role of the continental margins as a sink for
silica at the global scale. Our work also demonstrates that the effects of
changes in riverine dissolved silica on ocean biogeochemistry depend on the
availability of the other nutrients such as nitrogen, phosphorus and iron.
The model results suggest that the effects of reduced silica inputs due to
river damming are particularly pronounced in the Gulf of Bengal, Gulf of
Mexico and the Amazon plume where they negatively affect opal production.
While general circulation models are indispensable when assessing the
spatial variation in opal export production and biogenic Si burial in the
ocean, this study demonstrates that box models provide a good alternative
when studying the average global ocean response to perturbations of the
oceanic silica cycle (especially on longer time scales). |
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