Occurrence and partition ratios of radiocesium in an urban river during dry and wet weather after the 2011 nuclear accident in Fukushima

Murakami, Michio; Shibayama, Nao; Sueki, Keisuke; Mouri, Goro; Haechong, O; Nomura, Mihiro; Koibuchi, Yukio; Oki, Taikan

doi:10.1016/j.watres.2016.01.046

Cited by 12 publications

(6 citation statements)

References 21 publications

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“…3C-F). Calculated values were generally in agreement with experimentally observed sedimentation rates and 137 Cs concentrations (MLIT, (2014) 62 ; Murakami et al, (2015) 65 ). Vertical sections showed not only the observed sedimentation form but also the sediment flux (MLIT, (2014) 62 ).…”

Section: Resultssupporting

confidence: 85%

“…Five years after the Fukushima accident, the estimated ratio of decline in 137 Cs concentrations were higher than those predicted by redistribution processes in the Chernobyl region. The decline in 137 Cs concentrations during this period is attributed to the fast mobilisation of both water and 137 Cs with incorporation of the amphibious effects of sediment particle adsorption over urban land surfaces and river flow velocity, based on recent post-Fukushima measurements (Murakami et al, (2015) 65 ). The involvement of the fast mobilisation of both water and 137 Cs, and the effects on their decay curve contexts, exemplified the amphibious effects of sediment particle adsorption during wet periods known as the flash flood phenomenon.…”

Section: Resultsmentioning

confidence: 99%

“…5A). The coefficient of the exponential function from the works of Yamashita et al (2014) 2 and Murakami et al (2015) 65 was applied. The Chernobyl accident measurements of the time-dependent input function and parameter values in Eq.…”

Section: Resultsmentioning

confidence: 99%

“…The land use map was generated using Digital National Information. General features are described associated with the Tone River Basin 1A) and the artificial lake, Teganuma Basin (Murakami et al, (2015) 65 ). Time series of measurements of 137 Cs in the Edo River in the contaminated Tokyo region were taken from previous reports (MEXT, (2011a) 63 ; MEXT (2014) 66 ) and temporal variation in the 137 Cs concentration in soil has been reported by the reports.…”

Section: Methodsmentioning

confidence: 99%

“…The time period corresponded to the start of the second phase of the survey of Timms et al (2005) 21 . In addition, grab and composite samples were collected for 137 Cs every 3 to 4 weeks from May 2012 to January 2015 (Murakami et al, (2015) 65 ). Grab samples were also collected during wet weather.…”

Section: Methodsmentioning

confidence: 99%

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Reproduction of sediment deposition and prediction of 137Cs concentration in the major urban rivers of Tokyo

Mouri

2020

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Radioactive caesium-137 (137 cs) can be used as a tracer to infer sediment dynamics due not only to its long radioactive half-life but also its affinity for fine sediment. A novel advanced interpolation assessment was conducted to examine radionuclide activity in terraced land covered with volcanic ash soil in Tokyo, Japan, which had a time-dependent input function and incorporated the effects of mixed-sediment particle dynamic behaviour on radioactive decay. In addition, transport parameters derived from chernobyl measurements were applied as predictors of the long-term contamination of the cardinal urban rivers by the fallout from the tokyo electric power fukushima Daiichi nuclear power Plant (FDNPP) accident in 2011. The behaviour of suspended sediment substances, incorporating the effects of deposition and pickup, was assessed using a mixed-sediment particle dynamics model. The concentrations of 137 Cs adsorbed on fine sediment particles of each size fraction were determined. Removal of 137 Cs from the cardinal urban river channel had significant effects on both long-term decline, including extreme flash flood events, and the dynamic and time-dependent behaviours of interspersed 137 Cs and sediment activity. A novel advanced interpolation assessment method was used to examine radionuclide activity in terraced land covered with volcanic ash soil in Tokyo, Japan. The assessment procedure has a time-dependent input function and incorporates the effects of mixedsediment particle dynamics on this time dependence. The results indicated that sediment and 137 cs concentrations could decline more rapidly than observed in the Fukushima and Chernobyl regions. This rate of decrease depended on terraces covered with volcanic ash soil, which incorporated the effects of fine sediment behaviour for particle adsorption. In addition, comparatively large impacts were observed during extreme flash flooding events, which were associated with the land cover of the major urban river catchments in Tokyo. This work provides a new perspective for understanding 137 cs behaviour associated with reproduction of sediment deposition and prediction of 137 cs concentration in the major urban rivers of Tokyo, incorporating the effects of baseline 137 cs behaviour with the impact of sediment particle adsorption in a volcanic ash soil-covered terrace. Radionuclides, including radioactive 137 Cs, released from the FDNPP accident following the earthquake and tsunami of 11 March 2011, have risen to critical mass through interspersed deposition on surfaces, mainly through rainfall and discharge into water systems. Radioactive contaminants have accumulated in unusual environments, such as the river channels of urban areas, including within the perimeter of Tokyo (Ministry of Education Culture Sports Science and Technology, 2014; Mouri et al., (2014a) 1 ; Yamashita et al., (2014) 2 ; Mouri, (2016a) 3). Researchers have been investigating and estimating the dynamic behaviour and long-term trends of radionuclides following the 1986 accident in Chernoby...

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Section: Resultssupporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%