ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-13-1425-2013 Modelling the global atmospheric transport and deposition of radionuclides from the Fukushima Dai-ichi nuclear accident Christoudias T. 1 Lelieveld J. 1 2 The Cyprus Institute, Nicosia, Cyprus Max Planck Institute of Chemistry, Mainz, Germany 05 02 2013 13 3 1425 1438 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/13/1425/2013/acp-13-1425-2013.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/13/1425/2013/acp-13-1425-2013.pdf

We modeled the global atmospheric dispersion and deposition of radionuclides released from the Fukushima Dai-ichi nuclear power plant accident. The EMAC atmospheric chemistry – general circulation model was used, with circulation dynamics nudged towards ERA-Interim reanalysis data. We applied a resolution of approximately 0.5 degrees in latitude and longitude (T255). The model accounts for emissions and transport of the radioactive isotopes <sup>131</sup>I and <sup>137</sup>Cs, and removal processes through precipitation, particle sedimentation and dry deposition. In addition, we simulated the release of <sup>133</sup>Xe, a noble gas that can be regarded as a passive transport tracer of contaminated air. The source terms are based on Chino et al. (2011) and Stohl et al. (2012); especially the emission estimates of <sup>131</sup>I are associated with a high degree of uncertainty. The calculated concentrations have been compared to station observations by the Comprehensive Nuclear-Test-Ban Treaty Organisation (CTBTO). We calculated that about 80% of the radioactivity from Fukushima which was released to the atmosphere deposited into the Pacific Ocean. In Japan a large inhabited land area was contaminated by more than 40 kBq m<sup>-2</sup>. We also estimated the inhalation and 50-year dose by <sup>137</sup>Cs, <sup>134</sup>Cs and <sup>131</sup>I to which the people in Japan are exposed.

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