大気汚染に関する金属の研究(第2報) : 放射化分析法による降下ばいじん中のアルミニウム, マンガンの測定とその季節および地域の変動について

Measurements by radioactivation analysis were carried out for aluminium and manganese in deposits which were collected from various sampling points in Chiba areas. From the analytical data, the seasonal and geometrical fluctuations of the amount of aluminium or manganese in the deposits were also discussed. The deposits were collected monthly for a year, and each 10 mg ash of the deposit was irradiated for 1 min at neutron flux, 3×1010n/cm2·sec, (5 kw) for aluminium, and 8×1013n/cm2·sec, (10 Mw) for manganese, respectively, and their γ ray spectra were analyzed. (aluminium : 1.78 MeV, manganese : 0.83 MeV) The values of aluminium obtained by this method were coincided well to the ones of aluminium reported previously which were determined by the ordinary chemical analysis. Seasonal and geometrical fluctuations were not observed clearly for aluminium contents, however, they were quite definite in the case of manganese, and large amounts of manganese were found in deposits in the industrial divisions of Chiba, especially near to iron works.