13C and 15N Abundances in the Sediment Core (VER 92/1-St-10-GC2) from Northern Lake Baikal |
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| Authors: | K Yoshii E Wada N Takamatsu E B Karabanov T Kawai |
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| Institution: | 1. Center for Ecological Research, Kyoto University , 4-1-23 Simosakamoto, Otsu, 520-01, Japan;2. Faculty of Science , Toho University , Funabashi, 274, Japan;3. Limnological Institute, Siberian Division, Russian Academy of Sciences , P.O. Box 4199, Irkutsk, 664033, Russia;4. National Institute for Resources and Environment , Tsukuba, Ibaraki, 305, Japan |
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| Abstract: | Abstract Carbon and nitrogen stable isotope compositions of organic matter, TOC/TN ratio, and manganese concentration in a sediment core that was collected in northern part of Lake Baikal (VER92ST10-GC2, water depth at 922 m, about 3 m long) were investigated to elucidate the origin of the sedimentary organic matter and its associated environmental factors. The sediment core was composed of mainly two parts: turbidite sections and other sections. Constant δ13C and δ15N values of the turbidite sections were observed (- 26.8 ±0.2 ‰ for δ13C and 3.2 ± 0.1 ‰ for δ15N) throughout the core. The higher δ13C in turbidite sections (about - 27 ‰) than that of the other sections (- 31 to - 29 ‰) was clearly observed, and δ15N was different between turbidite sections (about 3‰) and other sections (3 to 5 ‰). δ13C of other sections was close to that of pelagic phytoplankton, indicating that sediment other than turbidite sections is composed of autochthonous components. The variation of stable isotopes in other sections may be possibly caused by the changes in either phytoplankton growth rate or contribution ratios of terrestrial to aquatic plants for δ13C. Either denitrification or fluctuation of δ15N in pelagic phytoplankton can be the cause of variable δ15N in other sections. |
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| Keywords: | Allochthonous autochthonous δ13C δ15N Lake Baikal manganese sediment |
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