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| Titel |
The effect of meter-scale lateral oxygen gradients at the sediment-water interface on selected organic matter based alteration, productivity and temperature proxies |
| VerfasserIn |
K. A. Bogus, K. A. F. Zonneveld, D. Fischer, S. Kasten, G. Bohrmann, G. J. M. Versteegh |
| 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 ; 9, no. 4 ; Nr. 9, no. 4 (2012-04-27), S.1553-1570 |
| Datensatznummer |
250006960
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| Publikation (Nr.) |
 copernicus.org/bg-9-1553-2012.pdf |
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| Zusammenfassung |
| A valid assessment of selective aerobic degradation on organic matter (OM)
and its impact on OM-based proxies is vital to produce accurate
environmental reconstructions. However, most studies investigating these
effects suffer from inherent environmental heterogeneities. In this study,
we used surface samples collected along two meter-scale transects and one
longer transect in the northeastern Arabian Sea to constrain initial OM
heterogeneity, in order to evaluate selective aerobic degradation on
temperature, productivity and alteration indices at the sediment-water
interface. All of the studied alteration indices, the higher plant alkane
index, alcohol preservation index, and diol oxidation index, demonstrated
that they are sensitive indicators for changes in the oxygen regime. Several
export production indices, a cholesterol-based stanol/stenol index and
dinoflagellate lipid- and cyst-based ratios, showed significant (more than
20%) change only over the lateral oxygen gradients. Therefore, these compounds
do not exclusively reflect surface water productivity, but are significantly
altered after deposition. Two of the proxies, glycerol dibiphytanyl glycerol
tetraether-based TEX86 sea surface temperature indices and indices
based on phytol, phytane and pristane, did not show any trends related to
oxygen. Nevertheless, unrealistic sea surface temperatures were obtained
after application of the TEX86,
TEX86L, and TEX86H
proxies. The phytol-based ratios were likely affected by the sedimentary
production of pristane. Our results demonstrate the selective impact of
aerobic organic matter degradation on the lipid and palynomorph composition
of surface sediments along a short lateral oxygen gradient and suggest that
some of the investigated proxies may be useful tracers of changing redox
conditions at the sediment-water interface. |
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