Palaeoclimatic reconstructions for the last 150,000 years based on stable isotope ratios of fossil pollen grains

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K20442
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Ritsumeikan University
• Principal Investigator: Yamada Keitaro 立命館大学, 立命館グローバル・イノベーション研究機構, 助教 (30815494)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: 安定同位体 / 古気候 / 花粉 / 年縞

Outline of Final Research Achievements

In this study, we extracted fossil pollen grains from the sediments of Lake Suigetsu, Fukui Prefecture, Japan, over the last 150,000 years, and measured oxygen and hydrogen stable isotope ratios of the extracted fossil pollen and collected modern pollen. The oxygen stable isotope ratios of fossil pollen grains fluctuate synchronously with those of Hulu stalagmite, suggesting a strong influence of the monsoon. High-precision palaeoclimatic reconstructions using stable isotope ratios have been limited in terrestrial regions due to insufficient available materials. This study will facilitate terrestrial palaeoclimatic reconstructions using stable isotope ratios and is expected to have future applications in a wide range of terrestrial sediments.

Free Research Field

古気候学

Academic Significance and Societal Importance of the Research Achievements

化石花粉の安定同位体比は古気候指標として有力視されてきたものの、化石花粉の高純度抽出の難しさから長らく実現していなかった。本研究は、セルソーターによる化石花粉の高純度抽出技術を用いることで、その安定同位体比による古気候復元を初めて実現した。この成果は、水月湖の新たな古気候情報を提供するだけでなく、安定同位体比を用いた古気候復元を多くの陸上堆積物でも可能とするもので、陸域の古気候変動の理解を前進させる大きなきっかけとなる可能性がある。