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| Titel |
A biomarker record of Lake El'gygytgyn, Far East Russian Arctic: investigating sources of organic matter and carbon cycling during marine isotope stages 1-3 |
| VerfasserIn |
A. R. Holland, S. T. Petsch, I. S. Castañeda, K. M. Wilkie, S. J. Burns, J. Brigham-Grette |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 9, no. 1 ; Nr. 9, no. 1 (2013-01-30), S.243-260 |
| Datensatznummer |
250017435
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| Publikation (Nr.) |
 copernicus.org/cp-9-243-2013.pdf |
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| Zusammenfassung |
| Arctic paleoenvironmental archives serve as sensitive recorders of past
climate change. Lake El'gygytgyn (Far East Russian Arctic) is a
high-latitude crater impact lake that contains a continuous sediment record
influenced by neither glaciation nor glacial erosion since the time of
impact 3.58 Ma ago. Prior research on sediments collected from Lake
El'gygytgyn suggest times of permanent ice cover and anoxia corresponding to
global glacial intervals, during which the sediments are laminated and are
characterized by the co-occurrence of high total organic carbon, microscopic
magnetite grains that show etching and dissolution, and negative excursions
in bulk sediment organic matter carbon isotope (δ13C) values.
Here we investigate the abundance and carbon isotopic composition of lipid
biomarkers recovered from Lake El'gygytgyn sediments spanning marine isotope
stages 1–3 to identify key sources of organic matter (OM) to lake sediments,
to establish which OM sources drive the negative δ13C excursion
exhibited by bulk sediment OM, and to explore if there are molecular and
isotopic signatures of anoxia in the lake during glaciation. We find that
during marine isotope stages 1–3, direct evidence for water column anoxia is
lacking. A ~4‰ negative excursion in bulk
sediment δ13C values during the Local Last Glacial Maximum
(LLGM) is accompanied by more protracted, higher magnitude negative
excursions in n-alkanoic acid and n-alkanol δ13C values that
begin 20 kyr in advance of the LLGM. In contrast, n-alkanes and the
C30 n-alkanoic acid do not exhibit a negative δ13C
excursion at this time. Our results indicate that the C24, C26 and
C28 n-alkanoic acids do not derive entirely from terrestrial OM sources,
while the C30 n-alkanoic acid at Lake El'gygytgyn is a robust indicator
of terrestrial OM contributions. Overall, our results strongly support the
presence of a nutrient-poor water column, which is mostly isolated from
atmospheric carbon dioxide during glaciation at Lake El'gygytgyn. |
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