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International Journal of Earth & Environmental Sciences Volume 2 (2017), Article ID 2:IJEES-134, 5 pages
https://doi.org/10.15344/2456-351X/2017/134
Research Article
Sr-90 Deposition Observed in Central and Northeast Honshu Island, Japan, after the Fukushima Dai-ichi Nuclear Power Plant Accident

Katsumi Hirose

Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyodaku, Tokyo 102-8554, Japan
Dr. Katsumi Hirose, Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioicho, Chiyodaku, Tokyo 102-8554, Japan; E-mail: hirose45037@mail2.accsnet.ne.jp
20 March 2017; 20 July 2017; 22 July 2017
Hirose K (2017) Sr-90 Deposition Observed in Central and Northeast Honshu Island, Japan, after the Fukushima Dai-ichi Nuclear Power Plant Accident. Int J Earth Environ Sci 2: 134. doi: https://doi.org/10.15344/2456-351X/2017/134

Abstract

Monthly depositions of anthropogenic radionuclides, which directly reflect atmospheric processes including emission from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), are an important probe to re-construct FDNPP accident sequence. Japanese radioactivity survey network monitored monthly 90Sr deposition after the FDNPP accident. The highest monthly 90Sr deposition (470±17 Bq m-2) was observed in March 2011 at Futaba near the FDNPP site, which is the same order of magnitude as that due to global fallout observed in 1963. The higher 90Sr deposition in March 2011 occurred in the Kanto and inland of the Tohoku areas. The monthly 90Sr deposition decreased with time, as did 137Cs. Atmospheric effect of the FDNPP-derived 90Sr continued more than 1 year. 90Sr/137Cs activity ratios in March 2011, which were in the range from 0.99 × 10-4 to 3 × 10-4, showed no large spatial variation. This result allowed us to estimate total atmospheric emission of 90Sr from the FDNPP accident from the total atmospheric release of 137Cs. The total release amount of 90Sr at an early stage of accident was calculated to be 2.7 – 3.6TBq.