[S-GL27] 地球年代学・同位体地球科学

[SGL27-P10] Compound-specific radiocarbon analysis of lipid biomarkers in surface sediment from Lake Kawaguchi, central Japan

*山本 真也¹、宮入 陽介²、横山 祐典²、菅 寿美³、小川 奈々子³、大河内 直彦³ (1.山梨県富士山科学研究所、2.東京大学大気海洋研究所、3.海洋研究開発機構)

キーワード：化合物レベル放射性炭素年代法、湖底堆積物、脂肪酸

Lake sediment in volcanic regions contains valuable information on past eruptive history, as well as environmental consequences that took place in the catchment along with volcanisms. In this study, we performed compound-specific radiocarbon analysis (CSRA) of lipid biomarkers in surface sediment from Lake Kawaguchi situated northern proximal to Mount Fuji, central Japan, including short-chain (C₁₆) and long-chain (C₂₄, C₂₆ and C₂₈) fatty acids. The results are compared with the ¹⁴C content of TOC, plant macrofossils (plant leaf and wood) and lake surface water in order to access their potential for dating tool in the lake sediment. The ¹⁴C concentration of the long-chain (C₂₄, C₂₆ and C₂₈) fatty acids ranged from –43 to –183‰, corresponding to ¹⁴C ages between 288 to 1554 years BP. This indicates that these acids contain substantial pre-aged materials in addition to those emitted from contemporary plant leaf waxes. In contrast, the short-chain (C₁₆) fatty acids showed a good agreement with the ¹⁴C concentration of lake surface water, suggesting that they are most likely derived from primary producers (diatom) in the present lake and have a potential to improve chronologies in the sedimentary sequence in which the occurrence of fossil leaves is rather limited.