Japan Geoscience Union Meeting 2016

Presentation information


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 1:45 PM - 3:15 PM A03 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

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), Chair:Michio Aoyama(Institute of Environmnetal Radioactivity, Fukushima University)

1:45 PM - 2:00 PM

[MAG24-13] Survey on riverine Cs-137 transport in Fukushima prefecture

*Keisuke Taniguchi1, Takayuki KURAMOTO1, Yuichi Onda2 (1.Centre for Environmental Creation Fukushima Prefecture, 2.University of Tsukuba)

Keywords:Radiocaesium, River

In Fukushima prefecture, river water is widely used for city water, agricultural water, and other purposes. Although the radioactivity in river water already declined enough to drink it, the activity and flux of radiocaesium should be observed in order to evaluate effects on the air dose rate due to deposition while flood events and transfer from agricultural products, wild animals and plants via ecosystem.
Suspended sediments samples were collected at 30 sites in Abukuma river system and Hamadori districts, and the discharge and turbidity were measured at the same sites. And then, particulate radiocaesium activities and fluxes were calculated.
Although the declining tendency of the radioactivity of particulate Cs-137 has been continuing, the declining rate slowed down after one year from the accident. In observation sites on Kuchibuto tributary, in which decontamination works were conducted by Ministry of the Environment, the radioactivity became lower after spring in 2014. The decline was probably caused by the decontamination of agricultural land (After stripping surface soil, soil without contamination was brought in and added).
In September 2015, a heavy rainfall event occurred. In lower reach of Abukuma River, the water discharge was at almost the same level as the event caused by typhoon Roke in September 2011. However, the particulate Cs-137 flux was one order to magnitude lower than that at September 2011, because the Cs-137 activity concentration decreased.