| Project/Area Number |
16201001
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 University |
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Principal Investigator |
MINAGAWA Masao Hokkaido University, 大学院・地球環境科学研究院, Professor (10250507)
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| Co-Investigator(Kenkyū-buntansha) |
NAGAO Seiya Hokkaido University, Faculty.Env.Earth Sci., Associate Professor (20343014)
IRINO Tomohisa Hokkaido University, Faculty.Env.earth Sci., Assist.Prof. (70332476)
KATO Yoshisa Tokai University, Dept.Oceanography, Professor (00152752)
NARITA Hisashi Tokai University, Dept.Oceanography, Associate Professor (50250501)
MURAYAMA Masafumi Kochi University (50261350)
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| Project Period (FY) |
2004 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥50,180,000 (Direct Cost: ¥38,600,000、Indirect Cost: ¥11,580,000)
Fiscal Year 2007: ¥3,640,000 (Direct Cost: ¥2,800,000、Indirect Cost: ¥840,000)
Fiscal Year 2006: ¥13,000,000 (Direct Cost: ¥10,000,000、Indirect Cost: ¥3,000,000)
Fiscal Year 2005: ¥11,960,000 (Direct Cost: ¥9,200,000、Indirect Cost: ¥2,760,000)
Fiscal Year 2004: ¥21,580,000 (Direct Cost: ¥16,600,000、Indirect Cost: ¥4,980,000)
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| Keywords | Tokachi river / Abe river / Shimanto river / Niyodo river / nitrate / phosphate / silicate / coastal biological production / 河川水 / 窒素過剰 / 窒素同位体 / 四国沿岸 / 同位体分析 / 酸素同位体 / 水素同位体 / 黒潮 / 15N / 陸上植物 / 輸送 / 栄養塩比 / 駿河湾 / 遠州灘 / 窒素負荷 / イベント / 基礎生産 / 栄養塩 / 沿岸海洋 / 沈降粒子 / 海洋生物 / 海底堆積物 / 炭素循環 |
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| Research Abstract |
We have investigated biogeochemical role of river runoff at several locations in Hokkaido, Central Honshu and Shikoku districts and have evaluated the contribution of these river water for the coastal biological production that is dealing with the marine carbon cycling. Based on geochemical observations including nutrient and isotopic analyses at Tokachi river, Abe river, Niyodo river, and Shimanto river, we found following results. (1) Nutrient loadings from Tokachi river were estimated as 1.3 and 0.009 mol/m^2/yr for DIN, and DIP, respectively. (2) These nutrient discharge can have dealings with 8.4 molC/m^2/yr as photosynthesis and may benefit for diatom production by their N/P and Si/N ratios. (3) Sporadic events with heavy precipitation can supply large effect mainly for nitrogen which provides potentially corresponding to 8% DIN supply of mean annual transport flux. (4) River discharge in the snow melting season would supply 30 to 40% of nutrient needed for coastal biological production, on the other hand particulate organic carbon make for less than one tenth of carbon fixation and less than a half of PON nitrogen. (5) The first class rivers in Shizuoka prefecture tend to have relatively lower nitrogen content ranging from 27 to 98 μM, but those in the second class rivers showed higher concentrations ranging from 82 to 504 mM and even wide variations. The phosphate and silicate concentrations are ranging from 0.21 to 9.2 μM and from 109 to 413 μM, respectively, reflecting difference of local environmental conditions such as water shed area, land utilization pattern and degree of civilizations.
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