Water mass structure and primary productivity in the sub-Arctic seas revealed from dissolved organic matter and optical properties

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H04250
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: National Institute of Polar Research (2020-2022); Hokkaido University (2019)
• Principal Investigator: Hirawake Toru 国立極地研究所, 先端研究推進系, 教授 (70311165)
• Co-Investigator(Kenkyū-buntansha): 山下 洋平 北海道大学, 地球環境科学研究院, 准教授 (50432224)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: CDOM / FDOM / 水塊 / 光吸収 / 蛍光 / 基礎生産

Outline of Final Research Achievements

Light absorption and fluorescence of chromophoric dissolved organic matter (CDOM) were investigated in the waters off Sanriku coast, the shelf region of the Bering Sea, and adjacent seas where seawaters with various characteristic distribute nearby each other and mixing. Using these optical characteristics of CDOM, we classified seawaters with the same characteristics (water masses) and succeeded to discriminate the water masses three dimensionally from data of fluorescence sensors and ocean color satellite sensors. Our results also suggested that water masses affected by coastal sediments and contributing to phytoplankton production could be discriminated.

Free Research Field

海洋光学

Academic Significance and Societal Importance of the Research Achievements

水塊の判別には水温と塩分が使われることが通例であるが、CDOMの情報を利用した本研究結果は、水温・塩分だけでは判別困難な沿岸堆積物の影響や、生物生産を促進させる水塊の生成過程の理解を大きく前進させるものである。今後、これらのプロセスを海洋生態系モデルに組みことで、我が国の持続的な海洋生物資源利用と管理および日本列島を含めた亜寒帯の生態学的研究と炭素循環研究の基礎情報として役立つと期待される。