1. Institute for Environmental Sciences Department of Radioecology, , 1-7 Ienomae, Obuchi, Rokkasho, Kamikita, Aomori 039-3212, Japan
2. Tokyo Electric Power Company Holdings, Inc. Fukushima Daiichi Decontamination & Decommissioning Engineering Company , Release and Environmental Monitoring Group, 1-1-3 Uchisaiwai-cho, Chiyoda-ku, Tokyo 100-8560, Japan
3. Tokyo Electric Power Company