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| Yukihiro Nojiri | |
| Head, Global Warming Mechanism Research Team, | |
| Global Environment Research Group, | |
| National Institute for Environmental Studies, Ministry of Environment | |
| 16-2, Onogawa, Tsukuba, Ibaraki 305-8604, Japan | |
| Tel: +81-298-50-2499 Fax: +81-298-50-2569 | |
| E-mail nojiri@nies.go.jp |
43,749,000 Yen
(FY 2000; 7,765,000 Yen)
For the improvement of the accuracy of the partial pressure measurement of CO2 (pCO2) in seawater, a precise comparison of existing systems were carried out in 1998 and 1999 with participation of eight Japanese and three foreign institutes utilizing a 170 t indoor seawater pool. The stable temperature and pCO2 of the pool facilitated for the precise comparison. The results showed 0.8% lower bias in the bubbling equilibrator. It was reasonable bias from the surface tension inside the bubble. By the results of the experiments, an excellent seawater pCO2 equilibrator of tandem design was developed, which is a combination of bubbling and mixer equilibrators. The results of on board equilibrators in the Japan-Canada ship-of-opportunity monitoring program from 1995 was carefully analyzed using the estimated analytical bias of the bubbling equilibrator. The agreement between the shower head and the bubbling equilibrator on board was excellent after 1997. The on board measurement was improved by the replacement of the bubbling equilibrator to tandem equilibrator. From 1999 November, a new on board pCO2 system was installed on another cargo ship between Japan and Canada. The use of the updated system gave much reliable observational data with 0.45 μatm accuracy in pCO2.
CO2, Partial pressure in seawater, Air-water equilibrator, accuracy, Inter-comparison