Japan Geoscience Union Meeting 2016

Presentation information

Poster

Symbol M (Multidisciplinary and Interdisciplinary) » M-AG Applied Geosciences

[M-AG24] Dynamics of radionuclides emitted from Fukuchima Dai-ichi Nuclear Power Plant in the environment

Mon. May 23, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Kazuyuki Kita(Faculty of Science, Ibaraki University), Yuichi Onda(Center for Research on Isotopes and Environmental Dynamics, University of Tsukuba), Teruyuki Nakajima(Japan Aerospace Exploration Agency), Yasuhito Igarashi(Atmospheric Environment and Applied Meteorology Research Department, Meteorological Research Institute), Masatoshi Yamada(Institute of Radiation Emergency Medicine, Hirosaki University), Chisato Takenaka(Graduate School of Bioagricultural Sciences, Nagoya University), masayoshi yamamoto(Low Level Radioactivity Laboratory, Kanazawa University), Jota Kanda(Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology), Atsushi Shinohara(Osaka university)

5:15 PM - 6:30 PM

[MAG24-P01] Radioactive particles in residual soil after strong acid leaching

*Yukihiko Satou1, Keisuke Sueki1, Kimikazu Sasa1, Kouki Kokubun2, Kouji Adachi3, Yasuhito Igarashi3 (1.Faculty of Pure and Applied Sciences, University of Tsukuba, 2.Centre for Environmental Creation Fukushima Prefecture, 3.Meteorological Research Institute)

Keywords: Radioactive particle, Silicate compound, Acid resistance

In March 2011, the Fukushima Dai-ichi Nuclear Power Plant (F1NPP) accident has been occurred, and consequently large amount of radionuclides discharged to the environment. Especially Cesium-137 (137Cs), which is radioisotope of cesium and it has 30 a of half-life, were remained in the environment for a long time. Understanding of the physical and chemical properties of the emitted radioactive cesium is important to accurately evaluate the possible human health impacts and to assess the long-term distributions of these radionuclides after deposition in residential areas, agricultural fields, mountains, and aquatic environments. Especially, the chemical form in soils is interesting at the point of decontamination of residence area and reconstruction of agricultural field. This study also analyzed chemical form of radiocesium in the soil collected at Motomiya city.
Soil sample was collected at the Motomiya city, Fukushima Prefecture, located of 40 km west from the F1NPP in October 2012. Concentration of 137Cs in soil was 8 kBq/kg (In March 11, 2011). Sequential extraction was performed (Five fraction was obtained, 1) water dissolve, 2) cation exchangeable, 3) organic form, 4) concentrated acid leachable, 5) residue.), and approximately 50% of 137Cs was remained in soil. Several number of spot type contamination were detected with autoradiography using an imaging plate. A spot was isolated from soil, and it was spherical particle. Constitution elements are Fe, Zn, Si, O, as well as Cs, which was detected using an energy dispersive X-ray spectrometry. These features are very similar to Cs-bearing radioactive particles isolated from air dust filter collected at the Tsukuba city by Adachi et al. (2013) and Abe et al. (2014). Therefore the particles distributed widely. In addition, dominant composition of particle is silicate of approximately 80 %. This result is consistent with Satou et al. (2015) and Yamaguchi et al. (2016). A silicate usually indicates acid resistance. These results suggested that the particulate form radiocesium is stable in environment, and it could be not remove by acid chemical treatment.