@misc{oai:repo.qst.go.jp:00065503,
 author = {鄭, 建 and 田上, 恵子 and ト, 文庭 and 内田, 滋夫 and 石井, 伸昌 and 鄭 建 and 田上 恵子 and ト 文庭 and 内田 滋夫 and 石井 伸昌},
 month = {Sep},
 note = {Since the Fukushima Daiichi nuclear power plant (FDNPP) accident in 2011, intensive studies on the distribution of released fission products, in particular 134Cs and 137Cs, in the environment have been conducted, and the activity ratio of 134Cs/137Cs has been widely used as a tracer for contamination source identification. However, due to the short half-life of 134Cs (2.06 y), this tracer will become unavailable in the future. Here, we investigated heavily contaminated environmental samples (litter, lichen and soil) collected from Fukushima forests for the long-lived 135Cs (half-life, 2x106 y) and the 135Cs/137Cs isotopic ratio. The determination of 135Cs and 137Cs in environmental samples was done using a newly developed ICP/MS/MS analytical method by combining AMP selective Cs adsorption and ion-exchange chromatographic separation techniques. For the first time, we obtained the isotopic composition of the 135Cs/137Cs isotopic ratio of the FDNPP-released radiocesium. We demonstrated that radiocesium was mainly released from the Unit 2 reactor. 135Cs/137Cs can be considered as a new tracer for source identification and long-term estimation of the mobility of released radiocesium in the environment., The 9th International Symposium on the natural Radiation Environment (NRE-IX)},
 title = {Isotopic ratio of Cs-135/Cs-137 as a new tracer for source identification and long-term environmental behavior studies on radioactive Cs released from the Fukushima nuclear accident},
 year = {2014}
}