| Project/Area Number |
07680562
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | HOKKAIDO TOKAI UNIVERSITY |
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Principal Investigator |
TAKAHASHI Kozo Hokkaido Tokai University, Department of Marine Sciences & Technology, School of Engineering, Professor, 工学部, 教授 (30244875)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1996: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1995: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Particle flux / Seasonal change / Interannual change / opal / Total mass flux / Calcium carbonate / Bering Sea / central subarctic Pacific / セディメント・トラップ / 時系列 / CaCO_3 / オパール / レデイオラリア / 円石藻 |
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| Research Abstract |
We have carried out an environmental research based on five-year long sediment trap samples which we have been collecting in the Bering Sea and in the central subarctic Pacific over the years since 1989. Station AB (53.5ﾟN,177ﾟW ; water depth 3788m) is located in the Aleutian Basin of the Bering Sea. The pelagic Station SA (49ﾟN,174ﾟW ; water depth 5406m) is centrally located in the entire subarctic Pacific. The sediment trap samples are synchronized at the two stations so that we can compare the fluxes.
Total mass fluxes were significantly greater at the marginal sea Station AB than at the pelagic Station SA for the first four years and moderately greater for the last year of the present experiment. This reflects the generally recognized higher productivity in the Bering Sea than the pelagic counterpart. Temporal patterns of the mass fluxes at the two stations located in different oceanic regimes generally paralleled, implying that temporal changes in their biological productivity is s
… More
trongly governed by a large scale seasonal climatic variability over the regions rather than local phenomena.
The primary reason for the difference in total mass flux at the two stations mainly stems from varying degrees in contribution of siliceous and calcareous planktonic assemblages. A significantly higher opal contribution is recognized at Station AB than at Station AB than at Station SA.At Station AB the biogenic particle fluxes are constituted largely of diatoms and thus coccolithophore contribution is relatively small. The magnitude of total mass fluxes is largely governed by percent opal fluxes. Such a tendency of the nodal importance of opal contribution in total mass flux can also be seen in other regions of the entire subarctic Pacific, supported by the literature values. On the contrary to the opal fluxes, at Station AB the CaCo_3 fluxes represent a slightly lower level than that at Station SA.
The obtained ratios of Corg/Cinorg are significantly greater than one for most of the time throughout the year in both regions, suggesting that preferentially greater organic carbon in cytoplasm is produced than inorganic carbon produced in calcareous shells in the surface layrs. This leads to a carbon sink situation which lowers pCO_2 in the surface layrs. Thus, the biological pump is effectively functioning and additional atmospheric Co_2 could be drawn into the upper ocean in these regions. When compared a greater efficiency in the biological pump is operating in the Bering Sea than in the pelagic subarctic Pacific. Less
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