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[B-1.10 Study on Exchange of CO₂ between Atmosphere, Hydrosphere and Biosphere Using Isotope Analysis(Final Report)]

[Contact Person]

Mukai Hitoshi
Senior Researcher, Global Environment Research Group
National Institute for Environmental Studies, Environmental Agency
16-2, Onogawa, Tsukuba, Ibaraki 305, Japan
Tel: +81-298-50-2536 Fax: +81-298-56-4680
E-mail: Inmukaih@nies.go.jp

[Total Budget for FY1994-1995]

26,861,000 Yen (FY1995; 13,543,000 Yen)

[Abstract]

　Variation of carbon isotope ratio of carbon dioxide is considered to be one of key information to study a carbon cycle on the earth. In this study, measurements of carbon and oxygen isotope ratios of carbon dioxide in oceanic atmosphere were tried. Oceanic air samples were collected over the Pacific ocean by using two cargo ships which ply periodically between Japan and Australia, and between Japan and Canada respectively. By this sampling, the air samples from wide latitudinal range and at various seasons could be obtained. The methods for isotope ratios measurements were studied and the precision under 0.07 permil was obtained for carbon isotope ratio measurement finally, in addition to the correction factor(about 0.2 permil) by the interference of nitrous oxide. This methods were applied to the some samples, and carbon isotope ratio was found to decrease with increase of its concentration. As for oxygen isotope ratio, the variation pattern was different from that of carbon dioxide, suggesting that both isotope ratios had potentials to trace their behavior.

[Key Words]

Carbon dioxide, Isotope ratios, Ocean, Soil , latitudinal distribution