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| Titel |
Late Holocene variations in Pacific surface circulation and biogeochemistry inferred from proteinaceous deep-sea corals |
| VerfasserIn |
T. P. Guilderson, M. D. McCarthy, R. B. Dunbar, A. Englebrecht, E. B. Roark |
| 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. 9 ; Nr. 10, no. 9 (2013-09-12), S.6019-6028 |
| Datensatznummer |
250085332
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| Publikation (Nr.) |
 copernicus.org/bg-10-6019-2013.pdf |
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| Zusammenfassung |
| δ15N and δ13C data obtained from samples of
proteinaceous deep-sea corals collected from the North Pacific Subtropical
Gyre (Hawaiian Archipelago) and the central equatorial Pacific (Line
Islands) document multidecadal to century-scale variability in the isotopic
composition of surface-produced particulate organic matter exported to the
deep sea. Comparison of the δ13C data, where Line Islands
samples are 0.6‰ more positive than the Hawaiian
samples, supports the contention that the North Pacific Subtropical Gyre is
more efficient than the tropical upwelling system at trapping and/or
recycling nutrients within the mixed layer. δ15N values from
the Line Islands samples are also more positive than those from the central
gyre, and within the Hawaiian samples there is a gradient with more
positive δ15N values in samples from the main Hawaiian Islands
versus the French Frigate Shoals in the Northwestern Hawaiian Islands. The
gradient in the Hawaiian samples likely reflects the relative importance of
algal acquisition of metabolic N via dissolved seawater nitrate uptake
versus nitrogen fixation. The Hawaiian sample set also exhibits a strong
decrease in δ15N values from the mid-Holocene to present. We
hypothesize that this decrease is most likely the result of decreasing
trade winds, and possibly a commensurate decrease in entrainment of more
positive δ15N-NO3 subthermocline water masses. |
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