日本地球惑星科学連合2019年大会

講演情報

[E] ポスター発表

セッション記号 B (地球生命科学) » B-PT 古生物学・古生態学

[B-PT04] Biomineralization and the Geochemistry of Proxies

2019年5月26日(日) 15:30 〜 17:00 ポスター会場 (幕張メッセ国際展示場 8ホール)

コンビーナ:豊福 高志(国立研究開発法人海洋研究開発機構)、北里 洋(国立大学法人東京海洋大学)、Bijma Jelle(アルフレッドウェゲナー極域海洋研究所)、廣瀬 孝太郎(早稲田大学  大学院創造理工学研究科 地球・環境資源理工学専攻)

[BPT04-P03] 瀬戸内海表層堆積物中の珪藻遺骸群集組成とバイオマーカー組成の比較

*廣瀬 孝太郎1中村 英人2安藤 卓人4浅岡 聡3沢田 健5 (1.早稲田大学  大学院創造理工学研究科 地球・環境資源理工学専攻、2.大阪市立大学大学院 理学研究科、3.神戸大学 内海域環境教育研究センター、4.北海道大学 極域研究センター、5.北海道大学 大学院理学研究院 地球惑星科学部門)

キーワード:珪藻群集、珪藻バイオマーカー、HBI、表層堆積物、瀬戸内海

We investigate the fossil diatom abundances and biomarker concentrations in marine sediment to assess their relationships. 14 sample of surface (uppermost 5 cm of sea bottom) sediments are taken in 5 areas (Aki-nada Bay, Hiuchi-nada Bay, Harimanada-Bay, Osaka Bay and Kii Strait) of Seto Inland Seas in July 2015. Additional 8 samples are taken in Harimanada-Bay in October 2015. Although the precise age of the core has not been determined yet, it could be deposited within 10 years, according to the sedimentation rates by previous study (Yasuhara et al., 2007).
Diatom species such as small Thalassiosiraspp., skeletonema costatum, resting spore of Chaetoceros spp. and Neodelphyneis pelagica, which were reported by previous study (Hirose et al., 2008), are observed as the dominant taxa in all samples. Rhizosolenia spp. and Pleurosigma spp., known HBI producers, were occurred in low proportions. As specific diatom biomarkers, we identified C25 di- and tri-unsaturated highly branched isoprenoids (HBIs), along with relatively minor amount of C25 and C35 cyclic HBIs. Total abundances of diatom valves and HBIs were generally correlated, probably reflecting variations of diatom production. Meanwhile, Aki-bay and some samples of Harima-nada Bay were characterized with relatively low abundance of HBIs relative to valves. In these area, focused analysis on the minor diatom taxa would be needed to provide quantitative dataset to discuss further relation of HBIs and produces and their spatial distribution.