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| Titel |
Water pH and temperature in Lake Biwa from MBT'/CBT indices during the last 280 000 years |
| VerfasserIn |
T. Ajioka, M. Yamamoto, K. Takemura, A. Hayashida, H. Kitagawa |
| 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 ; 10, no. 5 ; Nr. 10, no. 5 (2014-10-17), S.1843-1855 |
| Datensatznummer |
250117059
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| Publikation (Nr.) |
 copernicus.org/cp-10-1843-2014.pdf |
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| Zusammenfassung |
| We generated a 280 000 yr record of water pH and temperature in Lake Biwa,
central Japan, by analysing the methylation index (MBT′) and
cyclisation ratio (CBT) of branched tetraethers in sediments from piston and
borehole cores. Our aim was to understand the responses of precipitation and
air temperature in central Japan to the East Asian monsoon variability on
orbital timescales. Because the water pH in Lake Biwa is determined by
phosphorus and alkali cation inputs, the record of water pH should indicate
the changes in precipitation and temperature in central Japan. Comparison
with a pollen assemblage in a Lake Biwa core suggests that lake water pH was
determined by summer temperature in the low-eccentricity period before 55 ka,
while it was determined by summer precipitation in the high-eccentricity
period after 55 ka. From 130 to 55 ka, the variation in lake pH (summer
precipitation) lagged behind that in summer temperature by several thousand
years. This perspective is consistent with the conclusions of previous
studies (Igarashi and Oba, 2006; Yamamoto, 2009), in that the temperature
variation preceded the precipitation variation in central Japan. |
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