| Project/Area Number |
10554021
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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 | 展開研究 |
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| Research Field |
Meteorology/Physical oceanography/Hydrology
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
AOKI Shuji Graduate School of Science, Tohoku University, Associate Professor, 大学院・理学研究科, 助教授 (00183129)
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| Co-Investigator(Kenkyū-buntansha) |
OHORI Motoki Technical Research Section, Thermo Quest Co. Ltd., Chief, 技術開発部, 主任研究員
NAKAZAWA Takakiyo Graduate School of Science, Tohoku University, Professor, 大学院・理学研究科, 教授 (30108451)
大堀 基巳 サーモクエスト株式会社, 技術開発部, 主任研究員
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| Project Period (FY) |
1998 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥10,500,000 (Direct Cost: ¥10,500,000)
Fiscal Year 1999: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 1998: ¥5,900,000 (Direct Cost: ¥5,900,000)
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| Keywords | oxygen / high precision / measurement system / mass spectrometer / standard gases / 標準誤差 / 炭素循環 / Co_2濃度 / 大気 / 質量分析計 |
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| Research Abstract |
A high precision measurement system of atmospheric oxygen concentration has been developed by the research project. The system consisted mainly of a detector, double inlets made of pyrex glass, a high precision pressure adjuster and a computer. A mass spectrometer of the Nier-McKinney type was selected for the detector of the system. The fused-silica-capillaries of 25mm I.d. and 1.35m length were used for connection between the double inlets and the detector. Air samples could be introduced into the inlet at an atmospheric pressure by the capillary. We confirmed that fractionation of air components did not occurred in the capillary. We found that oxygen enrichment occurred at a part of lower temperature of airflow line. Therefore, the system was settled in our air-conditioned laboratory and the capillary with a very small heat capacity was covered by double insulation tubes. Isobaric interference for N2 due to the formation of CO from CO2 in the ion source of the mass spectrometer was a serious problem for the high precision measurements. An empirical formula for CO2 and O2 concentrations was established by an experiment for correction of the interference of air samples.
Standard gases for O2 measurements were prepared by ourselves. Natural air was collected and stored in a high-pressure cylinder through water vapor traps. Such a collection of large amount of air was made several times in different seasons to prepare standard gases of different O2 concentrations. To confirm stability of O2 concentration of these standards, we made mutual calibration between these standards for more than 1 years. As a result, all the standard gases were stable within +-20 per meg and any drift of O2 concentration could not observable.
The standard error of +-5.6 per meg for a sample analyzed in quadruplicate could be attained for the measurement system.
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