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| Titel |
Bacterial GDGTs in Holocene sediments and catchment soils of a high Alpine lake: application of the MBT/CBT-paleothermometer |
| VerfasserIn |
H. Niemann, A. Stadnitskaia, S. B. Wirth, A. Gilli, F. S. Anselmetti, J. S. Sinninghe Damsté, S. Schouten, E. C. Hopmans, M. F. Lehmann |
| 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 ; 8, no. 3 ; Nr. 8, no. 3 (2012-05-07), S.889-906 |
| Datensatznummer |
250005583
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| Publikation (Nr.) |
 copernicus.org/cp-8-889-2012.pdf |
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| Zusammenfassung |
| A novel proxy for continental mean annual air temperature (MAAT) and soil
pH, the MBT/CBT-paleothermometer, is based on the temperature (T) and
pH-dependent distribution of specific bacterial membrane lipids (branched
glycerol dialkyl glycerol tetraethers – GDGTs) in soil organic matter.
Here, we tested the applicability of the MBT/CBT-paleothermometer to
sediments from Lake Cadagno, a high Alpine lake in southern
Switzerland with a small catchment of 2.4 km2. We analysed the
distribution of bacterial GDGTs in catchment soils and in a
radiocarbon-dated sediment core from the centre of the lake, covering the
past 11 000 yr. The distribution of bacterial GDGTs in the catchment
soils is very similar to that in the lake's surface sediments, indicating a
common origin of the lipids. Consequently, their transfer from the soils
into the sediment record seems undisturbed, probably without any significant
alteration of their distribution through in situ production in the lake
itself or early diagenesis of branched GDGTs. The MBT/CBT-inferred
MAAT estimates from soils and surface sediments are in good agreement with
instrumental values for the Lake Cadagno region (~0.5 °C).
Moreover, downcore MBT/CBT-derived MAAT estimates match in timing and
magnitude other proxy-based T reconstructions from nearby locations for the
last two millennia. Major climate anomalies recorded by the
MBT/CBT-paleothermometer are, for instance, the Little Ice Age (~14th
to 19th century) and the Medieval Warm Period (MWP, ~9th to 14th
century). Together, our observations indicate the quantitative applicability
of the MBT/CBT-paleothermometer to Lake Cadagno sediments. In addition to
the MWP, our lacustrine paleo T record indicates Holocene warm phases at
about 3, 5, 7 and 11 kyr before present, which agrees in timing with other
records from both the Alps and the sub-polar North-East Atlantic Ocean. The
good temporal match of the warm periods determined for the central Alpine
region with north-west European winter precipitation strength implies a
strong and far-reaching influence of the North Atlantic Oscillation on
continental European T variations during the Holocene. |
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