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Aoyama, M. ., Meteorological Research Institute, Tsukuba, Japan, maoyama@mir-jma.go.jp
Tsumune, D. ., Central Research Institute of Electric Power Industry, Abiko, Japan, tsumune@criepi.denken.or.jp
Hamajima, Y. ., Kanazawa University, Kanazawa, Japan, hama@cacheibm.s.kanazawa-u.ac.jp

BUDGETS AND TEMPORAL CHANGE OF RADIOCAESIUM DISTRIBUTION RELEASED FROM FUKUSHIMA NPP ACCIDENTS IN THE NORTH PACIFIC OCEAN

In 2011 just before the Fukushima NPP accident, the 137Cs inventory in the North Pacific Ocean was about 70 PBq. The impact of the NPP accident to the North Pacific occurred through direct release and atmospheric deposition to ocean surface. Near the Fukushima site, 134Cs activities in surface water increased up to 67 × 106 Bq m-3 in April 2011. 134Cs activities decreased to about 2-5 × 104 Bq m-3 while activities in surface water several hundred km further east were 10 - 80 Bq m-3 and were not detected in the Kuroshio region south of 36 deg. N in August 2011. This indicates fast flushing of contaminated water by the Kuroshio Current. 134Cs was also detected in eastern North Pacific Ocean in April/May 2011 with activities ranging from 2 Bq m-3 to 12 Bq m-3 which indicates global transport of 134Cs by atmospheric transport. The total amount of direct release of 134Cs is estimated to be 3.5 ± 0.7 PBq and that by atmospheric transport is tentatively estimated to be 10.5 ± 2.5 PBq together with equivalent amount of 137Cs, respectively.

Session #:088
Date: 2/21/2012
Time: 10:30
Location: Ballroom E

Presentation is given by student: No