@misc{oai:repo.qst.go.jp:00071426,
 author = {ト, 文庭 and 福田, 美保 and 鄭, 建 and 青野, 辰雄 and 田上, 恵子 and 内田, 滋夫 and et.al and ト 文庭 and 福田 美保 and 鄭 建 and 青野 辰雄 and 田上 恵子 and 内田 滋夫},
 month = {Mar},
 note = {The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident caused the release of large amounts of radionuclides into the environment. The radionuclide contamination in the marine environment due to the FDNPP accident is of great scientific and public concern. In contrast with the intensive studies about the fission products (134Cs, 137Cs, 90Sr et al.), information about plutonium isotopes in the marine environment is limited[1]. Pu isotopes derived from the FDNPP accident have been detected in the soil and litter samples collected in the 20-30 km zone around the FDNPP site, revealing the release of Pu from the accident [2]. In our previous works, we determined the distribution of Pu isotopes in the marine sediments 30 km off Fukushima and observed no detectable Pu contamination from the FDNPP accident [3-5]. Pu isotopes are characterized by high particle affinity and they can easily be incorporated into the sea bottom sediment in marine environment. It has been suggested that if any Pu contamination from the FDNPP accident occurred in the ocean, it would remain in a very close area around the power plant site [6]. Thus the Pu contamination situation in the marine sediments within the 30 km zone around the FDNPP site needs to be investigated. 
  In this work, we determined the vertical distribution of Pu isotopes (239Pu, 240Pu, 241Pu) and Pu atom ratios (240Pu/239Pu, 241Pu/239Pu) in several sediment cores collected within the 30 km zone around the FDNPP site. For Pu analysis, ca. 2-40 g dried sediment sample was weighed out and spiked with 0.57 pg 242Pu as a yield monitor. The extraction of Pu was performed in a Teflon tube with 20-40 mL concentrated HNO3 on a hot plate at 180-200ºC for at least 4 h. A two-stage anion-exchange chromatographic method was employed for the separation of Pu and for the further purification of Pu prior to the ICP-MS analysis [5]. The observed results will be discussed for the source identification of Pu isotopes in these marine sediments. The influence of the FDNPP accident on the Pu contamination in the marine environment will also be assessed.   
This work was supported by the Kakenhi Grant-in-Aid for Scientific Research on Innovative Areas (24110004),  and partly supported by the Agency for Natural Resources and Energy, the Ministry of Economy, Trade and Industry (METI), Japan., 第１５回環境放射能研究会},
 title = {Pu distribution in the marine sediments within the 30 km zone around the Fukushima Dai-ichi Nuclear Power Plant site},
 year = {2014}
}