| Project/Area Number |
05452400
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Environmental dynamic analysis
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| Research Institution | OKAYAMA UNIVERSITY |
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Principal Investigator |
OHTAKI Eiji OKAYAMA UNIV.ENVIRON.SCI.AND TECH.PROFESSOR, 環境理工学部, 教授 (40033120)
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| Co-Investigator(Kenkyū-buntansha) |
TSUKAMOTO Osamu OKAYAMA UNIV.SCIENCE,ASSOC.PROFESSOR, 理学部, 助教授 (40027298)
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| Project Period (FY) |
1993 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥7,000,000 (Direct Cost: ¥7,000,000)
Fiscal Year 1995: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1994: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1993: ¥5,000,000 (Direct Cost: ¥5,000,000)
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| Keywords | EDDY CORRELATION METHOD / AERODYNAMIC METHOD / BULK METHOD / CARBON DIOXIDE / FLUX / 熱収支法 / 二酸化炭素フラックス |
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| Research Abstract |
The air-sea exchage rates of carbon dioxide is studied. The primary results obtained are summarized as follows : (1) The mean value of total carbon dioxide fluxes measured by the eddy correlation technique was about 0.10 mg m^<-2> s^<-1> with the standard deviation of 0.09 mg m^<-2> s^<-1>, showing the upward flux of carbon dioxide. These values are within the range obtained over the Sea of Japan during October 1986 and 1987, while present fluxes are about one tenth of the downward flux of carbon dioxide measured over actively growing paddy fields. It is noted that the carbon dioxide flux measured by the eddy correlation technique agrees with those measured by both the aerodynamic and bulk technique. (2) The pCO_2 instrument is designed to measure the carbon dioxide concentration of carrier gas which equilibrates with the sample seawater. Smple seawater of 150 ml is enough to determine pCO_2. The instrument can measure pCO_2 every 20 min and its measuring precision is about 2 ppm. (3) The temperature and salinity coefficients of pCO_2 are determined to be about 4.5%pCO_2/ﾟC and about 44 ppm per salinity unit, respectively. (4) The pCO_2 measured shows well defined diurnal variation with high values in the nighttime and low values in the daylight hours. This diurnal variation is due mainly to the photosynthetic activity of photoplanktons in seawater. (5) The CO_2 flux results in the change of pCO_2 in seawater. However, the relative change of pCO_2 due to the CO_2 flux is small less than 1 ppm per day. (6) The pCO_2 data show seasonal cycle with high values in summer season and low values in winter season. The amplitude of seasonal cycle is about 150 ppm. Comparing with the PCO_2 in the atmosphere, the pCO_2 in seawater is larger during periods from June to November, transporting carbon dioxide from the sea surface to the atmosphere, and smaller during periods from December to May through January, transporting carbon dioxide from the atmosphere to the seawater.
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