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1996 Fiscal Year Final Research Report Summary

Ocean surface biogeochemical processes and variation of carbon and nitrogen isotope ratios

Research Project

Project/Area Number 06453006
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field 地球化学
Research InstitutionNagoya University (1995-1996)
The University of Tokyo (1994)

Principal Investigator

SAINO Toshiro  Institute for Hydrospheric-Atmospheric Sciences, Nagoya University, Professor, 大気水圏科学研究所, 教授 (60126068)

Project Period (FY) 1994 – 1996
Keywordsparticulate organic matter / carbon isotope / nitrogen isotope / biogeochemical processes / phytoplankton / subarctic front / equatorial upwelling / Atlantic ocean
Research Abstract

Variation of carbon and nitrogen isotope ratios in suspended particulate materials (POM) were examined in a wide variety of the ocean environment. The study area extends to the northern North Pacific, equatorial central Pacific, north and south Atlantic Ocean, as well as coastal seas in Japan. It has been found that ; 1) In the northern North Pacific in summer, nitrate in the sea surface was depleted around the subarctic front, where phytoplankton abundance formed its maximum. To the north of the front, sea surface nitrate existed inrelatively high concentration, but the phytoplankton was less abundant than in frontal region. Nitrogen isotope ratio in the POM was low in the frontal region, and the carbon isotope ratio was higher than the expected value of non-blooming conditions. 2) In the equatorial Pacific, POM showed higher nitrogen isotope ratio in the central region compared to the eastern region. Nitrate nitrogen also showed the same trend in the isotope ratio. The reason for the … More above trend was speculated as follows : Nitrate supplied by the equatorial upwelling which is intense in the eastern region are translated to the west by the south equatorial current. During the translation to the west, the sea surface nitrate are taken up by phytoplankton with isotope fractionation, leaving nitrate and POM rich in ^<15>N.3) In the Atlantic, fron 50゚ N to 50゚ S,carbon isotope ratio of sea surface POM varies with isotope ratio of total inorganic carbon, as well as with primary productivity. It was shown that the variability of carbon isotope ratio, corrected for variability in isotope ratio of total inorganic carbon, correlated inversely with primary productivity per unit carbon biomass. 4) A new method to measure nitrogen isotope ratio in very low amount of nitrate was developed. 5) In the coastal front region, time scale for the vertical mixing of seawater was estimated to be about 2 days. It was found that carbon isotope ratio of the POM varied with a longer time scale than nitrogen. Less

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] 才野 敏郎: "栄養塩と生物活動" 現代海洋化学,月刊海洋号外. 8. 20-27 (1995)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Saito, T: "Role of sediment trap experiments in the study of plankton ecology : contribution to biological oceanography. In : Plankton Symposium, Use of Sediment Traps in the Study of Plankton Ecology." Bulletin of Plankton Society of Japan. 43. 153-158 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yanagi, T., T. Yamamoto, T. Ishimaru, and T. Saino: "Detailed cross-frontal strucutre of a tidal front in the Kii Channel, Japan. In : ″Coastal and Estuarine Studies″" American Geophysical Union. 50. 135-144 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yanagi, T., K. Tadokoro, and T. Saino: "Observation of convergence, divergence and sinking velocity at a thermohaline front in the Kii Channel, Japan." Continental Shelf Research. 16. 1319-1328 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Yanagi, T., X. Guo, T. Ishimaru, & T. Saino: "Detailed flow structure around a thermohaline front at the mouth of Ise Bay, Japan. In : ″Buoyancy Effects on Coastal and Estuarine Dynamics″" Coastal and Estuarine Studies. 53. 97-106 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 才野 敏郎: "物質循環のモニタリングと物質循環生物学" 月刊海洋号外(海洋物質循環と地球環境). 11. 100-105 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Saino, T.: "Nutrients and biological activity." Modern Marine Chemistry (special volume of Kaiyo Monthly). 8. 20-27 (1995)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Saino, T.: "Role of sediment trap experiments in the study of plankton ecology : contribution to biological oceanography." Bulletin of Plankton Society of Japan. 43 (2). 153-158 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yanagi, T., T.Yamamoto, T.Ishimaru, and T.Saino: "Detailed cross-frontal structure of a tidal front in the Kii Channel, Japan. In : "Coastal and Estuarine Studies"" American Geophysical Union. Vol.50. 135-144 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yanagi, T., K.Tadokoro, and T.Saino: "Observation of convergence, divergence and sinking velocity at a thermohaline front in the Kii Channel, Japan." Continental Shelf Research. 16 (10). 1319-1328 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Yanagi, T., X.Guo, T.Ishimaru, and T.Saino: "Detailed flow structure around a thermohaline front at the mouth of Ise Bay, Japan. In : "Buoyancy Effects on Coastal and Estuarine Dynamics"" Coastal and Estuarine Studies.Vol.53. 97-106 (1996)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Saino, T.: "Monitoring of material cycling in Matrial Cycling Biology." Material Cycling in the Ocean and Global Environment (special volume of Kaiyo Monthly). 11. 100-105 (1996)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1999-03-16  

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