Long-term observation (2011 – 2014) of natural and artificial radionuclides transported with aerosols at the Geological Survey of Japan

Abstract

In order to obtain the geochemical knowledge of material cycle and to contribute the concern of inhabitant about safety after the accident of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), the aerosol observation at the GSJ was continued and the new data in 2014 as well as those from 2011 are reported in this paper. The Cs radioisotopes in aerosols in October 2011 decreased to 10^-4 Bq/m³, one thousandth of those in April. In spring of each year, the concentration of Cs-137 decreased stepwise, to about 10^-5 Bq/m³ in January 2015, probably owing to the change of climate conditions. Natural Pb-210 and Be-7 activities correlated each other and decreased in summer and winter. Traces of Ce-141, Ce-144 and Sb-125 were observed in some samples taken in 2011.