Assessment of individual radionuclide distributions from the Fukushima nuclear accident
covering central-east Japan
Norikazu Kinoshitaa,1,2, Keisuke Suekia, Kimikazu Sasaa, Jun-ichi Kitagawaa, Satoshi Ikarashia, Tomohiro Nishimuraa,
Ying-Shee Wonga, Yukihiko Satoua, Koji Handaa, Tsutomu Takahashia, Masanori Satob, and Takeyasu Yamagatab
aAccelerator Mass Spectrometry Group, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba, Ibaraki 305-8577, Japan; and bGraduate School of Integrated
Basic Science, Nihon University, Sakura-Josui, Setagaya, Tokyo 156-8550, Japan
Edited by James E. Hansen, Goddard Institute for Space Studies, New York, NY, and approved September 29, 2011 (received for review July 24, 2011)
Full text: www.pnas.org/content/108/49/19526
A tremendous amount of radioactivity was discharged because of
the damage to cooling systems of nuclear reactors in the Fukushima
No. 1 nuclear power plant in March 2011. Fukushima and its
adjacent prefectures were contaminated with fission products
from the accident. Here, we show a geographical distribution
of radioactive iodine, tellurium, and cesium in the surface soils
of central-east Japan as determined by gamma-ray spectrometry.
Especially in Fukushima prefecture, contaminated area spreads
around Iitate and Naka-Dori for all the radionuclides we measured.
Distributions of the radionuclides were affected by the physical
state of each nuclide as well as geographical features. Considering
meteorological conditions, it is concluded that the radioactive
material transported on March 15 was the major contributor to
contamination in Fukushima prefecture, whereas the radioactive
material transported on March 21 was the major source in Ibaraki,
Tochigi, Saitama, and Chiba prefectures and in Tokyo.