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| Titel |
A new model for biomineralization and trace-element signatures of Foraminifera tests |
| VerfasserIn |
G. Nehrke, N. Keul, G. Langer, L. J. Nooijer, J. Bijma, A. Meibom |
| 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 ; 10, no. 10 ; Nr. 10, no. 10 (2013-10-29), S.6759-6767 |
| Datensatznummer |
250085380
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| Publikation (Nr.) |
 copernicus.org/bg-10-6759-2013.pdf |
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| Zusammenfassung |
| The Mg/Ca ratio of Foraminifera calcium carbonate tests is used as proxy
for seawater temperature and widely applied to reconstruct global
paleo-climatic changes. However, the mechanisms involved in the carbonate
biomineralization process are poorly understood. The current paradigm holds
that calcium ions for the test are supplied primarily by endocytosis of
seawater. Here, we combine confocal-laser scanning-microscopy observations of
a membrane-impermeable fluorescent marker in the extant benthic species
Ammonia aomoriensis with dynamic 44Ca-labeling and NanoSIMS
isotopic imaging of its test. We infer that Ca for the test in A.
aomoriensis is supplied primarily via trans-membrane transport, but that a
small component of passively transported (e.g., by endocytosis) seawater to
the site of calcification plays a key role in defining the trace-element
composition of the test. Our model accounts for the full range of Mg/Ca
and Sr/Ca observed for benthic Foraminifera tests and predicts the effect
of changing seawater Mg/Ca ratio. This places foram-based
paleoclimatology into a strong conceptual framework. |
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