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| Titel |
Prominent bacterial heterotrophy and sources of 13C-depleted fatty acids to the interior Canada Basin |
| VerfasserIn |
S. R. Shah, D. R. Griffith, V. Galy, A. P. McNichol, T. I. Eglinton |
| 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. 11 ; Nr. 10, no. 11 (2013-11-07), S.7065-7080 |
| Datensatznummer |
250085400
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| Publikation (Nr.) |
 copernicus.org/bg-10-7065-2013.pdf |
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| Zusammenfassung |
| In recent decades, the Canada Basin of the Arctic Ocean has experienced
rapidly decreasing summer sea ice coverage and freshening of surface waters.
It is unclear how these changes translate to deeper waters, particularly as
our baseline understanding of organic carbon cycling in the deep basin is
quite limited. In this study, we describe full-depth profiles of the
abundance, distribution and carbon isotopic composition of fatty acids from
suspended particulate matter at a seasonally ice-free station and a
semi-permanently ice-covered station. Fatty acids, along with suspended
particulate organic carbon (POC), are more concentrated and 13C-enriched
under ice cover than in ice-free waters. But this influence, apparent at
50 m depth, does not propagate downward below 150 m depth, likely due to
the weak biological pump in the central Canada Basin. Branched fatty acids
have δ13C values that are similar to suspended POC at all depths
and are more 13C-enriched than even-numbered saturated fatty acids at
depths above 3000 m. These are likely to be produced in situ by
heterotrophic bacteria incorporating organic carbon that is isotopically
similar to total suspended POC. Below surface waters, there is also the
suggestion of a source of saturated even-numbered fatty acids which could
represent contributions from laterally advected organic carbon and/or from
chemoautotrophic bacteria. At 3000 m depth and below, a greater relative
abundance of long-chain (C20–24), branched and unsaturated fatty acids
is consistent with a stronger influence of re-suspended sedimentary organic
carbon. At these deep depths, two individual fatty acids (C12 and
iso-C17) are significantly depleted in 13C, allowing for the
possibility that methane oxidizing bacteria contribute fatty acids, either
directly to suspended particulate matter or to shallow sediments that are
subsequently mobilized and incorporated into suspended particulate matter
within the deep basin. |
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