[AOS15-P14] 化学トレーサーを用いた東日本海盆深層における水塊の動態解析
キーワード：Water mass analysis, Rare Earth Elements, East Japan Basin
The Sea of Japan is a semi-closed ocean area, which results to an independent circulatory system. Especially in the East Japan Basin, various previous reports of deep circulation were established (Senjyu et al., 2005; Hatta and Zhang, 2006). However, the details of water masses were not clarified, because of limited observation stations. This study used multiple chemical tracers to analyze the dynamics of the deep water in East Japan Basin, and to clarify the existence of water advection in this region. Samples were collected from GEOTRACES JAPAN KH-10-02 cruise (Leg 2, June 21 to July 6, 2010). Dissolved oxygen (DO) and nutrients of seawater were analyzed on board. Rare earth elements (REEs) were extracted by chelate resin (NOBIAS Chelate PA-1) and measured by HR-ICP-MS on land.
The results of the four observation stations CR34 (140.00E, 45.67N), CR41 (138.93E, 44.20N), CR47 (138.21E, 42.82N), CR58 (135.92E, 40.43N), which located from northern to central region of East Japan Basin, were shown as follow. With comparing the DO and PO4-P vertical profiles of CR41 and CR47, PO4-P shows excess refer to the Redfield ratio, suggests the influence of particles. According to the REEs data, the CR41 and CR47 showed the same HREEs (Heavy REEs) patterns, indicates the advection from CR47 to CR41. Meanwhile, the same HREEs patterns also showed by CR41 500m and CR34 bottom water, suggests the advection from CR34 to CR41. Further, CR34 bottom water is influenced by resuspended particles or water masses out of East Japan Basin, which inferred by the higher LREEs (Light REEs) in CR34 bottom. In future, it is important to clarify the wide regional deep circulation with the biogeochemical observation in the northern part of Japan Sea and Okhotsk Sea.
The results of the four observation stations CR34 (140.00E, 45.67N), CR41 (138.93E, 44.20N), CR47 (138.21E, 42.82N), CR58 (135.92E, 40.43N), which located from northern to central region of East Japan Basin, were shown as follow. With comparing the DO and PO4-P vertical profiles of CR41 and CR47, PO4-P shows excess refer to the Redfield ratio, suggests the influence of particles. According to the REEs data, the CR41 and CR47 showed the same HREEs (Heavy REEs) patterns, indicates the advection from CR47 to CR41. Meanwhile, the same HREEs patterns also showed by CR41 500m and CR34 bottom water, suggests the advection from CR34 to CR41. Further, CR34 bottom water is influenced by resuspended particles or water masses out of East Japan Basin, which inferred by the higher LREEs (Light REEs) in CR34 bottom. In future, it is important to clarify the wide regional deep circulation with the biogeochemical observation in the northern part of Japan Sea and Okhotsk Sea.