2006 Fiscal Year Final Research Report Summary
Observational research for iron, biological productivity, and carbon cycle in the subarctic northwestern Pacific
| Project/Area Number |
16310019
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | Fisheries Research Agency |
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Principal Investigator |
ONO Tsuneo Fisheries Research Agency, Subarctic Fisheries Oceanography Division Hokkaido National Fisheries Research Institute, Chief Scientist (40371786)
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| Co-Investigator(Kenkyū-buntansha) |
KASAI Hiromi Fisheries Research Agency, Subarctic Fisheries Oceanography Division, Hokkaido National Fisheries Research Institute, Scientist (60371788)
NISHIOKA Jun Hokkaido University, Pan-Okhotsk research Center, Institute of Low Temperature Science, Assistant Professor (90371533)
WATANABE Yutaka Hokkaido University, Graduate School of Environmental Earth Science, Assistant Professor (90333640)
YOSHIMURA Takeshi Fisheries Research Agency, Central Research Institute of Electric Power industry, Scientist (20371536)
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| Project Period (FY) |
2004 – 2006
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| Keywords | iron / nutrient / Oyashio / primary production |
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| Research Abstract |
2-D iron distribution in the subarctic northwestern Pacific was investigated repeatedly from 2003 to 2006 with high spacio-temporal resolution equally to major nutrients. Seasonal and interannual variations of iron observed in the Oyashio domain brought us the following information :
1] Monthly-mean concentration of dissolved iron (DFe) in the Oyashio mixed layer varies in parallel with nitrate, with its maximum anteceding the Kosa season. Ratio of DFe to the nitrate is fairly constant throughout the year (ΔDFe/ΔN=27×10^<-6>[mol/mol]), and this ratio resembles those of North Pacific intermediate water (NPIW). Based on these observation results and a simple model calculation, it is concluded that the seasonal variation of Dfe in the Oyashio mixed layer is mainly governed by spring-summer biological consumption and winter recirculation from the NPIW. Iron input from the dust deposition is implied to have small effect to the mixed-layer iron cycle, although small-scale high iron patch might sometimes be generated by local iron deposition.
2] More than half of the DFe data observed in Oyashio mixed layer at the bloom-termination period shows roughly constant value of 0.25 nM, implying that the bloom-forming diatoms incur significant iron limitation below this iron level. In spring, iron reaches this lower-limit faster than nitrate, forming iron-limited ecosystem conditions at the end of spring bloom. In summer, however, the ultimate depletion of mixed layer nitrate occurs faster than that of DFe at July, forming nitrate-limited ecosystem in the summer Oyashio domain.
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Research Products
(9 results)
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[Journal Article] Iron supply to the western subarctic Pacific : Importance of iron export from the Sea of Okhotsk.
Author(s)
Nishioka, J., T. Ono, H. Saito, T. Nakatsuka, S. Takeda, T. Yoshimura, K. Suzuki, K. Kuma, S. Nakabayashi, D. Tsumune, H. Mitsudera, W. K. Johnson and A. Tsuda
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Journal Title
J. Geophys. Res. (in press)
Pages: 112
Description
「研究成果報告書概要(欧文)」より
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[Book] 月刊海洋号外432006
Author(s)
小熊 幸子
Total Pages
82-91
Publisher
安定同位体を用いた沿岸親潮域の水塊分布変動の把握
Description
「研究成果報告書概要(和文)」より
