Nationwide survey and behavior of tritium in air in China

Research Project

Project/Area Number	04044078
Research Category	Grant-in-Aid for international Scientific Research
Allocation Type	Single-year Grants
Section	Joint Research
Research Institution	Nagoya University
Principal Investigator	IKEBE Yukimasa Nagoya University, professor, 工学部, 教授 (50023073)
Co-Investigator(Kenkyū-buntansha)	REN Tianshan Laboratory of Industrial Hygiene, 工業衛生実験所, 教授王作元衛生部, 工業衛生実験所, 教授 NAGAMINE Koichiro Nagoya University, 工学部, 助手 (10242843) IIDA Takao Nagoya University, 工学部, 助教授 (50089843) WANG Zuoyuan Laboratory of Industrial Hygiene
Project Period (FY)	1992 – 1993
Project Status	Completed (Fiscal Year 1993)
Budget Amount *help	¥3,500,000 (Direct Cost: ¥3,500,000) Fiscal Year 1993: ¥1,900,000 (Direct Cost: ¥1,900,000) Fiscal Year 1992: ¥1,600,000 (Direct Cost: ¥1,600,000)
Keywords	Tritium / Water Vapor / Environmental Behavior / China / Regional Distribution / Sampling / Atmosphere / Seasonal Variation / 環境トリチウム / Passive法 / 濃度変動 / トリチウム分布 / 大気中動態
Research Abstract	A nationwide survey of tritium in water vapor has been carried out in China for providing data used for analyzing regional scale behaviors of atmospheric tritium in East Asia. Besides the usual active method using motive power, a newly developed passive method using no pump was used for sampling water vapor with molecular sieves. An apparatus for withdrawing water from absorbed vapor was constructed and installed at Laboratory of Industrial Hygiene, Ministry of Public Health, Beijing, China. The distillation of withdrew water sample and tritium radioactivity measurement with a liquid scintillation counter have been made at the Laboratory. Sampling of water vapor by the passive method was carried out every two months from June 1992 to August 1993 at 13 cities in China and 5 cities in Japan (Sapporo, Sendai, Nagoya, Kumamoto, Naha). Results of measurement are as follows : 1) Regional distributions of tritium in water vapor in East Asia were obtained every two months. A distribution for annual mean value was also obtained. 2) At Urmuchi and Lanchow, most high annual mean concentration of about 15 Bq/l was observed. The next high group (8-11 Bq/l) includes Harbin, Chanchun, Beijing, Sian, Lhasa, and Wuchang and Chentu follows the group. Concentrations at coastal region (Hangchow, Fuzhou, Sinsen) show low level, and five points in Japan belong the most low level group (1-2 Bq/l). 3) From the regional distribution map, we can see both inland effect and latitude effect. The effect of past nuclear explosion test should be studied later. Sampling by the active method had been made every two days for ten days in each season at Beijing, Lanchow and Fuzhou. Analyzing some date by using two-layer trajectory model, we got fairly good agreement between the calculated concentration level and measured one.