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| Titel |
Climate dependent diatom production is preserved in biogenic Si isotope signatures |
| VerfasserIn |
X. Sun, P. Andersson, C. Humborg, B. Gustafsson, D. J. Conley, P. Crill, C.-M. Mörth |
| 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 ; 8, no. 11 ; Nr. 8, no. 11 (2011-11-29), S.3491-3499 |
| Datensatznummer |
250006212
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| Publikation (Nr.) |
 copernicus.org/bg-8-3491-2011.pdf |
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| Zusammenfassung |
| The aim of this study was to reconstruct diatom production in the subarctic
northern tip of the Baltic Sea, Bothnian Bay, based on down-core analysis of
Si isotopes in biogenic silica (BSi). Dating of the sediment showed that the
samples covered the period 1820 to 2000. The sediment core record can be
divided into two periods, an unperturbed period from 1820 to 1950 and a
second period affected by human activities (from 1950 to 2000). This has
been observed elsewhere in the Baltic Sea. The shift in the sediment core
record after 1950 is likely caused by large scale damming of rivers. Diatom
production was inferred from the Si isotope composition which ranged between
δ30Si −0.18‰ and +0.58‰ in BSi, and assuming fractionation
patterns due to the Raleigh distillation, the production was shown to be
correlated with air and water temperature, which in turn were correlated
with the mixed layer (ML) depth. The sedimentary record showed that the
deeper ML depth observed in colder years resulted in less production of
diatoms. Pelagic investigations in the 1990's have clearly shown that diatom
production in the Baltic Sea is controlled by the ML depth. Especially after
cold winters and deep water mixing, diatom production was limited and
dissolved silicate (DSi) concentrations were not depleted in the water
column after the spring bloom. Our method corroborates these findings and
offers a new method to estimate diatom production over much longer periods
of time in diatom dominated aquatic systems, i.e. a large part of the
world's ocean and coastal seas. |
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