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Iijima, Kazuki; Hayashi, Seiji*; Tamaoki, Masanori*
Global Environmental Research (Internet), 24(2), p.85 - 93, 2021/06
Environmental radioactive contamination by the Fukushima Daiichi Nuclear Power Plant accident has clearly been declining during the passage of almost 10 years from the accident. However, the prolongation of radioactive contamination in natural ecosystems probably derived from forested area without decontamination is pointed out by many studies, so more detailed examination will be needed for environmental dynamics of bioavailable radiocesium and its transfer to ecosystems. Also for influence of radiation to organisms, effects of evacuation on wild organisms are more pronounced than direct effect from radiation, especially in Fukushima evacuation area.
Matsunaga, Takeshi; Ueno, Takashi; Amano, Hikaru; Y.Tkatchenko*; A.Kovalyov*; Watanabe, Miki*; Onuma, Yoshikazu*
Journal of Contaminant Hydrology, 35, p.101 - 113, 1998/00
Times Cited Count：44 Percentile：75.22(Environmental Sciences)no abstracts in English
Cs in the Kuji River, JapanMatsunaga, Takeshi; Amano, Hikaru; Yanase, Nobuyuki
Applied Geochemistry, 6(2), p.159 - 167, 1991/00
Times Cited Count：36 Percentile：65.63(Geochemistry & Geophysics)no abstracts in English
Miyahara, Kaname
no journal, ,
This presentation focuses on JAEA's R&D for enhancing Fukushima environmental recovery to address the needs for better scientific and technological capabilities to assess, predict, and minimize the impact of radiological contamination and illustrate how to enhance the understanding of radiation and associated risks in the public.
Miyahara, Kaname
no journal, ,
A large fraction of the radiocesium inventory captured by forest canopies has gradually migrated to the ground through rain wash-off and leaf fall and transited within the litter layer, eventually being captured (in most cases) by the forest soil layer underneath. Catchment-scale movement of Cs-loaded suspended sediments in the aquatic environment has been observed through streams, rivers and estuaries into the coastal marine environment, accounting for trapping of Cs in ponds, lakes and dams, including its transfer back to the terrestrial environment (mainly flood plains during periods of high river flow). We are developing a comprehensive knowledge base on Cs transport mechanisms in specific Fukushima environments which can form the basis of rigorous future dose forecasts and plans for countermeasures required to reduce such doses.
Iijima, Kazuki; Kitamura, Akihiro; Miyahara, Kaname
no journal, ,
Understandings of transport behaviour of radiocesium in the environment were overviewed, and distribution of other radionuclides was compared to that of radiocesium. Annual discharge of radiocesium from forest with soil particles and fine litter were around 0.1% of those of initially deposited and independent to vegetation and slope if there was enough litter and small plants. In the stream water taken nearby the flowing out point showed higher concentration of dissolved radiocesium that that of groundwater, suggesting that dissolved radiocesium was generated due to the degradation of litter or the desorption from soil and dissolved. The concentration of dissolved radiocesium in river water was lower than 1 Bq/L in all river systems. Since the direction dependency on the off-site distribution of these radionuclides were similar to that of observed in the FDNPS site, the estimation of the on-site distribution based on the off-site one was considered to be available.
Cs concentrations in east Japanese riversTsuji, Hideki*; Ishii, Yumiko*; Hayashi, Seiji*; Shin, M.*; Taniguchi, Keisuke*; Arai, Hirotsugu*; Kurihara, Momo*; Yasutaka, Tetsuo*; Kuramoto, Takayuki*; Nakanishi, Takahiro; et al.
no journal, ,
Controlling factor of dissolved Cs concentrations in 66 in East Japan rivers was investigated. Dissolved Cs concentrations decreased by one order of magnitude between 2012 and 2017. Normalized dissolved Cs concentrations correlated well with building area ratios. Topographic wetness index generally predicted dissolved Cs concentrations. The high concentration of dissolved Cs in urban area cannot be explained by water quality condition.
Iijima, Kazuki
no journal, ,
Behavior of radioactive cesium in the environment from the forest to the estuary was discussed by comparing the data obtained from observations and laboratory experiments with the analytical results for the eight river systems in coastal area of Fukushima Prefecture. Concentration of dissolved radioactive cesium in river water decreased with time, with seasonal variations that became higher in summer and lower in winter. The behavior was analyzed with a simulation tool based on the water circulation simulator GETFLOWS. The behavior of particulate radioactive cesium was well reproduced. On the other hand, in case of dissolved fraction, although the concentration level could be roughly reproduced, the seasonal variation and the temporary concentration increase at the beginning of heavy rain could not be reproduced. In the current simulation, only the desorption is considered as the dissolving process, so that the contribution of other processes was considered.
Iijima, Kazuki
no journal, ,
Behavior of radioactive cesium in the environment from the forest to the estuary was discussed by comparing the data obtained from observations and laboratory experiments with the analytical results for the eight river systems in coastal area of Fukushima Prefecture. Concentration of dissolved radioactive cesium in river water decreased with time, with seasonal variations that became higher in summer and lower in winter. The behavior was analyzed with a simulation tool based on the water circulation simulator GETFLOWS. The behavior of particulate radioactive cesium was well reproduced. On the other hand, in case of dissolved fraction, although the concentration level could be roughly reproduced, the seasonal variation and the temporary concentration increase at the beginning of heavy rain could not be reproduced. In the current simulation, only the desorption is considered as the dissolving process, so that the contribution of other processes was considered.
