Atmospheric deposition of 7Be, 40K, 137Cs and 210Pb during 1993-2001 at Tokai-mura, Japan

To evaluate the radionuclide migration from the atmosphere to the ground surface, atmospheric deposition samples were collected from 1993 to 2001 with a basin set up at Tokai-mura, Japan. Monthly samples were evaporated to dryness to obtain residual samples and measured with a Ge detector for ⁷Be, ⁴⁰K, ¹³⁷Cs and ²¹⁰Pb. According to the analysis, clear seasonal variations with spring peaks of deposition weight and deposition amounts of all the radionuclides were found. The analysis also showed that these radinuclides can be divided into two groups, each having different carrier particle sizes and, hence, different deposition processes.