Variation of B[lc]e-7 concentration in Tokushima

Abstract

Monitoring measurements of environmental radioactivities in an atmosphere give important information, e.g. elucidation of local and global atmospheric migration and evaluation of human risks and environmental exposures. At present, the atmospheric Be-7 radioactive nuclide in the environmental radioactivities has been used as a radio tracer to elucidate the degree of horizontal mixing of global atmosphere migration within the surface air layer. The Be-7 nuclide has been produced by a spallation-reaction between cosmic ray and gas fractions (e.g. N2 and O2 gases) in a stratosphere where is located upon a surface air layer. The Be-7 nuclides are attached to aerosol particles in the stratosphere, and they are transported to the surface air layer with taking a few months. In addition, the another atmospheric radioactive nuclide of Pb-214 in the environmental radioactivities is one of the progenies of Rn-222 which is emitted from the ground surface into the atmosphere, and also exists in the atmosphere with the same as a form attached to aerosol particles. In this work, it was supposed that to examine the correlation between the Be-7 and Pb-214 atmospheric concentrations in the surface air layer at a certain local place (i.e. Tokushima, eastern Shikoku island) will reflect the geological and meteorological background of the observing locality and the neighboring area.