大気降下物中のBe-7、Pb-210濃度の経年変化

Abstract

The aerosols direct and indirect effects on the radiative forcing are estimated as a large factor. The characteristics of aerosols at any location depend on the type of sources and sinks prevailing in that particular region. Urban aerosol is a topic of current interest, because of rapidly increasing global urban populations. Natural Radionuclides, Be-7(half-life 53.29 d) and Pb-210(half-life 22.3 y) in total deposition and aerosol samples were measured. These two radionuclides with their different sources are therefore useful to understand the mechanisms of aerosol behavior such as removal from the atmosphere and transportation. All monthly depositions were collected in Kyushu University (Fukuoka City) and University Forest (Sasaguri) by the tray. The aerosol in the atmosphere was collected by high volume air sampler. All samples were measured with the gamma-ray spectrometry using Ge semiconductor detector. The seasonal change of Be-7 and Pb-210 depositions in all deposition samples was observed showing a spring peak in Be-7 depositional pattern. Seasonal variation of each radionuclide is the same, however, is not the same from year to year.