Geographical distribution and time variation of atmospheric carbon-dioxide in and around Tokyo were investigated. The instrument used in this survey is an ASSA-1 infrared analyzer (0_??_1000 ppm, CO2). The sampling and analyzing systems are illustrated in Fig. 1. Special attentions are taken to eliminate dust and water vapor in the atmosphere by use of a precipitation bottle and a hand-made condenser.
Geographical distributions of CO2 are shown in Fig. 2. Fig. 2-A shows the change of CO2 off coast of Tokyo, and Figs. 2-B and C are the distributions in and around Tokyo. The influence of CO2 originated from Tokyo and its vicinity extends more than 100km.
Several examples of the diurnal variation of CO2 at Rissyo University (Shinagawa-ku, Tokyo) are shown in Fig. 3. Daily maximum concentration of CO2 usually exceeds 500ppm and sometimes it reaches about 660ppm. These extreme values are observed under a calm and inversion condition, particularly in the colder seasons.
In Fig. 4, the seasonal variation of CO2 at Rissyo University, both monthly mean value (circle) and monthly range, is illustrated. The concentration reaches its minimum in summer when combustion of fuel is less than other seasons and photosynthesis of plant is more active. The maximum value is observed in winter, and the extreme maximum is observed under a calm and inversion condition. The winter minimum does not differ largely from that in summer, because strong winter monsoon eliminates high concentration. The annual mean value during 1972_??_1973 is about 350ppm, which exceeds the world average by 25ppm.
