YOSHIOKA Katsuhiro Shimane Prefectural Institute of Public Health and Environmental Science, Senior Researcher, 主任研究員
KOMURA Kazuhisa Kanazawa University, Department of Science, Professor, 理学部, 教授 (00110601)
MORIIZUMI Jun Nagoya University, Graduate School of Engineering, Research Associate, 工学研究科, 助手 (90303677)
金 潤信 漢陽大学, 産業医学研究所, 所長(研究職)
池邊 幸正 名古屋大学, 工学研究科, 教授 (50023073)
|Budget Amount *help
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 1999: ¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1998: ¥2,000,000 (Direct Cost: ¥2,000,000)
The study on a long distance transportation of atmospheric pollution and man-made radionuclides has been important. The recent rapid development of computer enables to calculate an enormous and complicated program, and evolve the numerical model available for prediction in a behavior of materials. However, it is now difficult to estimate the movement of all elements considering physical and chemical characteristics. Radon-222 is a noble gas, and has comparatively long half-life of about 3.82d. Therefore, ィイD1222ィエD1Rn is a useful natural radioactive tracer. To measure the atmospheric ィイD1222ィエD1Rn concentrations along the current of air mass from Asian Continent to Japan, Electrostatic continuous ィイD1222ィエD1Rn monitors were set up at Yantai in China, Seoul and Tonhe in Korea, and Oki island, Kanazawa, and Nagoya in Japan.
The annual mean ィイD1222ィエD1Rn concentrations were 8.4±1.9 Bq・mィイD1-3ィエD1, 2.2±0.8 Bq・mィイD1-3ィエD1, 3.5±1.1 Bq・mィイD1-3ィエD1, 5.6±0.7 Bq・mィイD1-3ィエD1, 5.3±1.9 Bq・mィイD1-3ィエD1 at Seoul, Gokamura, Yokooyama, Kanazawa, and Nagoya, respectively. The ィイD1222ィエD1Rn concentration at each location showed a clear seasonal pattern of a spring-summer minimum and an autumn-winter maximum. The seasonal variation results from that the monitoring location is covered with mainly a maritime air mass during summer and a continental air mass in winter. The rapid increases of concentrations were often observed when a cold and warm fronts passed over the monitoring location. Then, the atmospheric pollution and OィイD23ィエD2 concentration also showed same variations. The three-dimensional dispersion model could be verified by using a reliable data obtained at Oki island.