H089-0023
The transfer of fallout radionuclides by Fukushima Daiichi Nuclear Power Plant Accident revealed by intensive monitoring network

Thursday, 10 December 2020
Poster
Yuichi Onda1, Keisuke Taniguchi2, Kazuya Yoshimura3, Hiroaki Kato1, Junko Takahashi4, Yoshifumi Wakiyama5 and Hugh Smith6, (1)University of Tsukuba, Center for Research in Isotopes and Environmental Dynamics, Tsukuba, Japan, (2)Fukushima prefecture centre for environmental creation, Research Department, Miharu, Japan, (3)Japan Atomic Energy Agency, Fukushima, Japan, (4)University of Tsukuba, Tsukuba, Japan, (5)Fukushima University, Fukushima, Japan, (6)Plymouth University, Plymouth, United Kingdom
Abstract:
The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released the most significant quantity of radiocaesium into the terrestrial environment since Chernobyl. The detailed river monitoring after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident over the last 9 years provides new insight into the link between fine sediment delivery and radionuclide mobility in the terrestrial environment.

We started sediment and Cs-137 outflow from plot scale monitoring (Wakiyama et al., 2019), headwater catchments (Iwagami et al., 2019), Paddy field (Wakahara et al. 2014). Also, we install river monitoring sites at six sites from June 2011 to quantify radiocesium fluxes by measuring discharge and turbidity, and sampling bulk suspended sediment and water. From December 2012, we installation of a further 24 monitoring sites to give 30 stations in total to cover most of the rivers in an 80-km radius from FDNPP (Taniguchi et al., 2019).

The factors controlling different declining trends between watersheds across the fallout zone were investigated and found that both radiocesium flux and the rate of decline in activity concentrations in rivers were an order of magnitude higher than rates measured after Chernobyl. In Fukushima, the initial fallout and vertical movement of radionuclide in the land and forest, and subsequent transport and redistribution through hydrological and geomorphological processes in cropland, Urban area, Paddy field, and forested area. Our finding revealed that land use is a key control of the sources of suspended particulate matter entering river networks, contributing to declining rates of radiocesium flux.

Wakiyama et al. (2015) J. Environ. Radioact. DOI: 10.1016/j.jenvrad.2019.105990

Iwagami et al. (2019) J. Environ. Radioact. DOI: 10.1016/j.jenvrad.2019.106001

Wakahara et al (2014) Environ. Sci. Process. Impacts DOI: 10.1039/c4em00262h

Taniguchi et al (2019) Environ. Sci. Technol. DOI:10.1021/acs.est.9b02890

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