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Vandromme R, Hayashi S, Tsuji H, Evrard O, Grangeon T, Landemaine V, Laceby JP, Wakiyama Y, Cerdan O. Lessons learnt on the impact of an unprecedented soil decontamination program in Fukushima on contaminant fluxes. Proc Natl Acad Sci U S A 2023; 120:e2301811120. [PMID: 37844225 PMCID: PMC10614835 DOI: 10.1073/pnas.2301811120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Accepted: 09/08/2023] [Indexed: 10/18/2023] Open
Abstract
In the context of elevated concerns related to nuclear accidents and warfare, the lessons learnt from the Fukushima Daiichi Nuclear Power Plant accident in 2011 are important. In particular, Japanese authorities implemented an ambitious decontamination program to reduce the air dose rate in order to facilitate the return of the local inhabitants to previously evacuated areas. This approach contrasts the strategy adopted in Chernobyl, where the most contaminated areas remain off limits. Nonetheless, the effectiveness of the Japanese decontamination strategy on the dispersion of radioactive contaminant fluxes across mountainous landscapes exposed to typhoons has not been quantified. Based on the unique combination of river monitoring and modeling in a catchment representative of the most impacted area in Japan, we demonstrate that decontamination of 16% of the catchment area resulted in a decrease of 17% of sediment-bound radioactive fluxes in rivers. Decontamination operations were therefore relatively effective, although they could only be conducted in a small part of the area due to the dominance of steep forested slopes. In fact, 67% of the initial radiocesium contamination was calculated to remain stored in forested landscapes, which may contribute to future downstream radiocesium dispersion during erosive events. Given that only a limited proportion of the initial population had returned in 2019 (~30%), it raises the question as to whether decontaminating a small percentage of the contaminated area was worth the effort, the price, and the amount of waste generated?
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Affiliation(s)
- Rosalie Vandromme
- Risk and Prevention Division, Bureau de Recherches Géologiques et Minières (BRGM), F-45060, Orléans, France
| | - Seiji Hayashi
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Science, Miharu, Tamura, Fukushima 963-7700, Japan
| | - Hideki Tsuji
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Science, Miharu, Tamura, Fukushima 963-7700, Japan
| | - Olivier Evrard
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Institut Pierre Simon Laplace (IPSL), Unité Mixte de Recherche 8212 Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), CNRS, Université de Versailles Saint-Quentin (UVSQ), Université Paris-Saclay, Gif-sur-Yvette F-91191, France
| | - Thomas Grangeon
- Risk and Prevention Division, Bureau de Recherches Géologiques et Minières (BRGM), F-45060, Orléans, France
| | - Valentin Landemaine
- Risk and Prevention Division, Bureau de Recherches Géologiques et Minières (BRGM), F-45060, Orléans, France
| | - John Patrick Laceby
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE), Institut Pierre Simon Laplace (IPSL), Unité Mixte de Recherche 8212 Commissariat à l'Énergie Atomique et aux Énergies Alternatives (CEA), CNRS, Université de Versailles Saint-Quentin (UVSQ), Université Paris-Saclay, Gif-sur-Yvette F-91191, France
- Airshed and Watershed Stewardship Branch, Environment and Protected Areas, Government of Alberta, Calgary, AB T2L 2K8, Canada
| | - Yoshifumi Wakiyama
- Radioisotope Geoscience Division, Institute of Environmental Radioactivity, University of Fukushima, Fukushima 960-1296, Japan
| | - Olivier Cerdan
- Risk and Prevention Division, Bureau de Recherches Géologiques et Minières (BRGM), F-45060, Orléans, France
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2
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Ikenoue T, Shimadera H, Nakanishi T, Kondo A. Thirty-year simulation of environmental fate of 137Cs in the Abukuma River basin considering the characteristics of 137Cs behavior in land uses. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 876:162846. [PMID: 36924964 DOI: 10.1016/j.scitotenv.2023.162846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 02/22/2023] [Accepted: 03/09/2023] [Indexed: 06/18/2023]
Abstract
The Fukushima Daiichi Nuclear Power Plant accident caused a radioactive contamination of deposited radionuclides, including 137Cs, on the land surface. Cesium-137 deposited on the land surface was strongly adsorbed on soil particles and was then washed off through soil erosion. Trends of temporal variation of 137Cs wash-off varied greatly depending on land use. Therefore, it is important to reflect the characteristics of 137Cs migration processes in each land use to clarify the long-term fate of 137Cs. In this study, a 30-year simulation of environmental fate of 137Cs was conducted using a distributed radiocesium prediction model, taking into account the characteristics of the 137Cs behavior in each land use. Overall, in the Abukuma River basin, the 137Cs transported into the ocean for 30 years was estimated to correspond to 4.6 % of the initial deposition in the basin, and the effective half-life of 137Cs deposited in the basin was estimated to be 3.7 years shorter (by 11.6 %) than its physical half-life. These results suggested that 137Cs deposited from the accident could still remain for decades. Based on the analysis of the 137Cs behavior in land use, in 2011, the contribution of 137Cs export to the ocean from urban lands was estimated to correspond to 70 % of the total 137Cs export. Meanwhile, from 2012 to 2040, the contribution of 137Cs export from agricultural lands was estimated to correspond to 75 % of the total 137Cs export. The reduction ratios excluding radioactive decay of 137Cs remained in areas with and without human activities for 30 years after the accident, defined as the ratios of the total outflow to the initial deposition, were estimated to be 11.5 %-17.7 % and 0.4 %-1.4 %, respectively. These results suggested that human activities enhance the reduction of 137Cs remaining in land in the past and future.
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Affiliation(s)
- Tsubasa Ikenoue
- Japan Atomic Energy Agency, 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan; Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
| | | | - Takahiro Nakanishi
- Japan Atomic Energy Agency, 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan
| | - Akira Kondo
- Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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3
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Gao Z, Zhang Q, Li J, Wang Y, Dzakpasu M, Wang XC. New conceptualization and quantification method of first-flush in urban catchments: A modelling study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 873:162271. [PMID: 36801410 DOI: 10.1016/j.scitotenv.2023.162271] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Revised: 02/09/2023] [Accepted: 02/12/2023] [Indexed: 06/18/2023]
Abstract
A major challenge for runoff pollution control lies in the quantification and identification of the first-flush. At present, there is a lack of reasonable theoretical methods to guide engineering practices. To remedy this deficiency, a novel method of cumulative pollutant mass vs. cumulative runoff volume (M(V)) curve simulation is proposed in this study. Subsequently, the first-flush phenomenon was redefined based on the M(V) curve simulation and demonstrate that the first-flush exists until the derivative of the simulated M(V) curve is equal to 1 (Ft' = 1). Consequently, a mathematical model for first-flush quantification was developed. The Root-Mean-Square-Deviation (RMSD) and Pearson's Correlation Coefficient (PCC), as objective functions, were used to evaluate the performance of the model and the Elementary-Effect (EE) method was used to analyze the sensitivity of the parameters. The results indicated the satisfactory accuracy of the M(V) curve simulation and first-flush quantitative mathematical model. The NSE values exceeding 0.8 and 0.938, respectively, were obtained by analyzing 19 rainfall-runoff data for Xi'an, Shaanxi Province, China. The wash-off coefficient "r" was demonstrably the most sensitive factor influencing the model performance. Therefore, interactions between "r" and the other model parameters should be focused on to highlight the overall sensitivities. Overall, this study posits a novel paradigm shift from the traditional dimensionless definition criterion to redefine and quantify first-flush, which has significant implications for urban water environment management.
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Affiliation(s)
- Zan Gao
- Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Qionghua Zhang
- Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China; International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Xi'an University of Architecture and Technology, Xi'an 710055, China.
| | - Jie Li
- Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Yufei Wang
- Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Mawuli Dzakpasu
- International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Xi'an University of Architecture and Technology, Xi'an 710055, China; School of Environmental and Municipal Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China
| | - Xiaochang C Wang
- Key Lab of Northwest Water Resource, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an 710055, China; International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Xi'an University of Architecture and Technology, Xi'an 710055, China
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4
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Sekudewicz I, Gąsiorowski M. Spatial and vertical distribution of 137Cs activity concentrations in lake sediments of Turawa Lake (Poland). ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:80882-80896. [PMID: 35727507 DOI: 10.1007/s11356-022-21417-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 06/07/2022] [Indexed: 06/15/2023]
Abstract
The main objective of this research was to study the spatial and vertical distribution of 137Cs activity concentrations in the bottom sediments of Turawa Lake 32 years after the Chernobyl fallout to investigate possible factors responsible for the post-fallout migration and accumulation of 137Cs in the selected reservoir. The results demonstrated a strong relationship between the increasing 137Cs and 40K activity concentrations and the decreasing grain size of sediments. Significant amounts of 137Cs were detected in the bottom sediments deposited in the deeper parts of the reservoir (especially near the dam). Therefore, this research showed that Turawa Lake can be an important trap for sediments polluted with 137Cs. Moreover, disturbed vertical distribution of 137Cs activity concentrations in the sediment columns collected from the littoral zone of this lake was observed, which is probably related to the bottom erosion intensified by wind-wave action, bioturbations, and water-level fluctuations. In the profundal zone, the vertical distribution of 137Cs activity concentrations was undisturbed, which indicates stable sedimentation conditions in this part of Turawa Lake.
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Affiliation(s)
- Ilona Sekudewicz
- Institute of Geological Sciences, Polish Academy of Sciences, Twarda St. 51/55, 00818, Warsaw, Poland.
| | - Michał Gąsiorowski
- Institute of Geological Sciences, Polish Academy of Sciences, Twarda St. 51/55, 00818, Warsaw, Poland
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5
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Konoplev A. Fukushima and Chernobyl: Similarities and Differences of Radiocesium Behavior in the Soil-Water Environment. TOXICS 2022; 10:toxics10100578. [PMID: 36287858 PMCID: PMC9608664 DOI: 10.3390/toxics10100578] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 08/30/2022] [Accepted: 09/24/2022] [Indexed: 05/29/2023]
Abstract
In the wake of Chernobyl and Fukushima accidents, radiocesium has become a radionuclide of most environmental concern. The ease with which this radionuclide moves through the environment and is taken up by plants and animals is governed by its chemical forms and site-specific environmental characteristics. Distinctions in climate and geomorphology, as well as 137Cs speciation in the fallout, result in differences in the migration rates of 137Cs in the environment and rates of its natural attenuation. In Fukushima areas, 137Cs was strongly bound to soil and sediment particles, with its bioavailability being reduced as a result. Up to 80% of the deposited 137Cs on the soil was reported to be incorporated in hot glassy particles (CsMPs) insoluble in water. Disintegration of these particles in the environment is much slower than that of Chernobyl-derived fuel particles. The higher annual precipitation and steep slopes in Fukushima-contaminated areas are conducive to higher erosion and higher total radiocesium wash-off. Among the common features in the 137Cs behavior in Chernobyl and Fukushima are a slow decrease in the 137Cs activity concentration in small, closed, and semi-closed lakes and its particular seasonal variations: increase in the summer and decrease in the winter.
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Affiliation(s)
- Alexei Konoplev
- Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima 960-1296, Japan
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6
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Niida T, Wakiyama Y, Takata H, Taniguchi K, Kurosawa H, Fujita K, Konoplev A. A comparative study of riverine 137Cs dynamics during high-flow events at three contaminated river catchments in Fukushima. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 821:153408. [PMID: 35090916 DOI: 10.1016/j.scitotenv.2022.153408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 01/18/2022] [Accepted: 01/21/2022] [Indexed: 06/14/2023]
Abstract
This study presents the temporal variations in riverine 137Cs concentrations and fluxes to the ocean during high-flow events in three coastal river catchments contaminated by the Fukushima Daiichi Nuclear Power Plant accident. River water samples were collected at points downstream in the Niida, Ukedo, and Takase Rivers during three high-flow events that occurred in 2019-2020. Variations in both the dissolved and particulate 137Cs concentrations appeared to reflect the spatial pattern of the 137Cs inventory in the catchments, rather than variations in physico-chemical properties of water and suspended solid. Negative relationships between the 137Cs concentration and δ15N in suspended solid were found in all rivers during the intense rainfall events, suggesting an increased contribution of sediment from forested areas to the elevation of particulate 137Cs concentration. The 137Cs flux ranged from 0.33 to 19 GBq, depending on the rainfall erosivity. The particulate 137Cs fluxes from the Ukedo River were relatively low compared with the other two rivers and were attributed to the effect of the Ogaki Dam reservoir upstream. The percentage of 137Cs desorbed in seawater relative to 137Cs in suspended solids ranged from 2.8% to 6.6% and tended to be higher with a higher fraction of exchangeable 137Cs. The estimated potential release of 137Cs desorbed from suspended solids to the ocean was 0.022-0.57 GBq, and its ratio to the direct flux of dissolved 137Cs was 0.12-6.2. Episodic sampling during high-flow events demonstrated that the particulate 137Cs flux depends on catchment characteristics and controls 137Cs transfer to the ocean.
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Affiliation(s)
| | | | - Hyoe Takata
- Institute of Environmental Radioactivity, Fukushima University, Japan
| | | | - Honoka Kurosawa
- Graduate School of Symbiotic Systems Science and Technology, Fukushima University, Japan
| | - Kazuki Fujita
- Fukushima Prefectural Centre for Environmental Creation, Japan
| | - Alexei Konoplev
- Institute of Environmental Radioactivity, Fukushima University, Japan
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7
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Konoplev A, Wakiyama Y, Wada T, Ivanov M, Komissarov M, Nanba K. Reconstruction of time changes in radiocesium concentrations in the river of the Fukushima Dai-ichi NPP contaminated area based on its depth distribution in dam reservoir's bottom sediments. ENVIRONMENTAL RESEARCH 2022; 206:112307. [PMID: 34756914 DOI: 10.1016/j.envres.2021.112307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 09/20/2021] [Accepted: 10/26/2021] [Indexed: 06/13/2023]
Abstract
Radionuclide depth distribution in bottom sediments in deep-water zones of dam reservoirs, where no sediment mixing occurs, can be used to reconstruct time changes in particulate activity concentrations of radionuclides strongly bound to bottom sediments. This approach was used to analyze the 137Cs concentration profile in a bottom sediment core collected from Ogaki dam reservoir on the Ukedo River in the Fukushima Dai-ichi nuclear power plant contaminated zone in October 2019. The derived 137Cs particulate concentrations provided a basis for estimating the dissolved concentration and its temporal trend in the Ukedo River, using the mean value of the apparent 137Cs distribution coefficient. The reconstructed particulate and dissolved 137Cs concentrations and their temporal trends are consistent with monitoring data. The annual mean particulate and dissolved 137Cs wash-off ratios were also calculated for the period of eight years after the accident. Interestingly, the particulate 137Cs wash-off ratios for the Ukedo River at Ogaki dam were found to be similar to those for the Pripyat River at Chernobyl in the same time period after the accident, while the dissolved 137Cs wash-off ratios in the Ukedo River were an order of magnitude lower than the corresponding values in the Pripyat River. Both the particulate and dissolved 137Cs wash-off ratios in the Ukedo River declined faster during the first eight years after the FDNPP accident than predicted by the diffusional model, most likely, due to greater natural attenuation and, to some extent, remediation measures implemented on the catchments in Fukushima.
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Affiliation(s)
- Alexei Konoplev
- Institute of Environmental Radioactivity, Fukushima University, Kanayagawa 1, Fukushima, 960-1296, Japan.
| | - Yoshifumi Wakiyama
- Institute of Environmental Radioactivity, Fukushima University, Kanayagawa 1, Fukushima, 960-1296, Japan
| | - Toshihiro Wada
- Institute of Environmental Radioactivity, Fukushima University, Kanayagawa 1, Fukushima, 960-1296, Japan
| | - Maxim Ivanov
- Faculty of Geography, Moscow State University, Moscow, 119991, Russia; Institute of Geography, Russian Academy of Science, Russia
| | | | - Kenji Nanba
- Institute of Environmental Radioactivity, Fukushima University, Kanayagawa 1, Fukushima, 960-1296, Japan
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8
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Takahashi J, Hihara D, Sasaki T, Onda Y. Evaluation of contribution rate of the infiltrated water collected using zero-tension lysimeter to the downward migration of 137Cs derived from the FDNPP accident in a cedar forest soil. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 816:151983. [PMID: 34843790 DOI: 10.1016/j.scitotenv.2021.151983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 11/22/2021] [Accepted: 11/22/2021] [Indexed: 06/13/2023]
Abstract
The vertical distribution of 137Cs in forest soil is important for predicting air dose rates and future cycling in forest ecosystems. However, there are many unexplained questions about the mechanisms of its downward migration. In this study, the 137Cs flux by rainfall infiltration was observed for three years from August 2017 using zero-tension lysimeters in a mature cedar forest where monitoring of the vertical distribution of 137Cs has been conducted since 2011. As a result, the 137Cs concentration in infiltrated water through the litter layer, 5 cm and 10 cm showed a tendency to be high in summer, but no such seasonal variation was found at 20 cm. Although the 137Cs inventory in the litter layer has been exponentially decreasing, the annual 137Cs fluxes in infiltrated water through the litter layer were almost the same in three years, and about 0.14-0.17% of the deposition density of 137Cs. Comparing these 137Cs fluxes with the apparent amounts of downward migration of 137Cs estimated from the change in the vertical distribution of 137Cs, the contribution rate of the infiltrated water to downward migration of 137Cs from litter to soil was calculated to be 8.5-17.7%. Similarly, the contribution rate in mineral soil layers was calculated to be 0.6-0.8% on a measured basis and estimated to be 3.0 ± 0.2% after correcting the amount of collected water, which is a problem with zero-tension lysimeter. It indicates that rainfall infiltration can explain a small part of the downward migration of 137Cs, thus further studies are required to clarify the contribution rate of remaining mechanisms such as advection-diffusion, colloidal transport, physical mixing, bioturbation, and growth and death of plant roots.
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Affiliation(s)
- Junko Takahashi
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Japan.
| | - Daichi Hihara
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan
| | | | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Japan
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9
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Otosaka S, Kamidaira Y, Ikenoue T, Kawamura H. Distribution, dynamics, and fate of radiocesium derived from FDNPP accident in the ocean. J NUCL SCI TECHNOL 2021. [DOI: 10.1080/00223131.2021.1994480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Shigeyoshi Otosaka
- Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan
| | - Yuki Kamidaira
- Research Group for Environmental Science, Japan Atomic Energy Agency, Ibaraki, Japan
| | - Tsubasa Ikenoue
- Research Group for Environmental Science, Japan Atomic Energy Agency, Ibaraki, Japan
| | - Hideyuki Kawamura
- Research Group for Environmental Science, Japan Atomic Energy Agency, Ibaraki, Japan
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10
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Yoshimura K. Air dose rates and cesium-137 in urban areas—deposition, migration, and time dependencies after nuclear power plant accidents. J NUCL SCI TECHNOL 2021. [DOI: 10.1080/00223131.2021.1973608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Kazuya Yoshimura
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Fukushima, Japan
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11
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Nakanishi T, Funaki H, Sakuma K. Factors affecting 137Cs concentrations in river water under base-flow conditions near the Fukushima Dai-ichi Nuclear Power Plant. J Radioanal Nucl Chem 2021. [DOI: 10.1007/s10967-021-07735-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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12
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Dataset on the 6-year radiocesium transport in rivers near Fukushima Daiichi nuclear power plant. Sci Data 2020; 7:433. [PMID: 33319799 PMCID: PMC7738531 DOI: 10.1038/s41597-020-00774-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/13/2020] [Indexed: 11/08/2022] Open
Abstract
Radiocesium released from the Fukushima Daiichi nuclear power plant (FDNPP) and deposited in the terrestrial environment has been transported to the sea through rivers. To study the long-term effect of riverine transport on the remediation process near the FDNPP, a monitoring project was initiated by the University of Tsukuba. It was commissioned by the Ministry of Education, Culture, Sports, Science, and Technology, and the Nuclear Regulatory Commission in June 2011, and was taken over by the Fukushima Prefectural Centre for Environmental Creation from April 2015. The activity concentration and monthly flux of radiocesium in a suspended form were measured in the project. This provides valuable measurement data to evaluate the impact of the accidentally released radiocesium on residents and the marine environment. It can also be used as verification data in the development and testing of numerical models to predict future impacts.
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Ikenoue T, Shimadera H, Kondo A. Impact of soil erosion potential uncertainties on numerical simulations of the environmental fate of radiocesium in the Abukuma River basin. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 225:106452. [PMID: 33186798 DOI: 10.1016/j.jenvrad.2020.106452] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 10/14/2020] [Accepted: 10/17/2020] [Indexed: 06/11/2023]
Abstract
The Fukushima Dai-ichi Nuclear Power Plant accident in March 2011 resulted in the deposition of significant quantities of radionuclides, including radiocesium (137Cs), over a wide area. Most of the deposited 137Cs is strongly adsorbed on fine soil particles such as clay and silt near the ground surface. Therefore, to estimate the environmental fate of 137Cs, it is necessary to predict its transport with eroded sediment in rainfall-runoff processes. In this study, a distributed radiocesium prediction model was applied to simulations of 137Cs transport associated with hydrological processes in the Abukuma River Basin, the largest river system in Fukushima, over the period of 2011-2012. The soil erosion potential, which is a key input to the distributed radiocesium prediction model, was estimated using the Universal Soil Loss Equation (USLE). This study focused on the uncertainty in estimating the environmental fate of 137Cs associated with the USLE factors. The USLE has five physically meaningful factors: the rainfall and runoff factor (R), soil erodibility factor (K), topographic factor (LS), cover and management factor (C), and support practice factor (P). Because the USLE factors were determined using various methods, R, LS, and the product of C and P (C×P) were divided into two, three, and five cases, respectively, based on previous studies. Therefore, we conducted 30 different simulations. The average total 137Cs outflow during the computational period in the simulation cases using the same USLE factors was 13.3 and 11.7 TBq for R (two cases), 12.6, 13.9 and 10.9 TBq for LS (three cases), and 26.5, 8.64, 0.47, 22.8 and 4.03 TBq for C×P (five cases). For the total outflow, C and P had the highest uncertainty of all the USLE factors. The outflow rates of the average total 137Cs in the simulation cases using the same C and P from the croplands and forest areas and from the undisturbed croplands and paddy fields were 62-91% and 18-34%, respectively. These results were due to the high erodibility of the croplands, the large forest areas in grids with high 137Cs deposition density, and the high concentration of 137Cs in the soil of the undisturbed croplands and paddy fields. This study indicates that land use, especially forest areas, croplands, and undisturbed paddy fields, has a significant impact on the environmental fate of 137Cs.
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Affiliation(s)
- Tsubasa Ikenoue
- Japan Atomic Energy Agency, 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki, 319-1195, Japan.
| | | | - Akira Kondo
- Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
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14
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Takata H, Aono T, Aoyama M, Inoue M, Kaeriyama H, Suzuki S, Tsuruta T, Wada T, Wakiyama Y. Suspended Particle-Water Interactions Increase Dissolved 137Cs Activities in the Nearshore Seawater during Typhoon Hagibis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2020; 54:10678-10687. [PMID: 32786583 DOI: 10.1021/acs.est.0c03254] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Distributions of 137Cs in dissolved and particulate phases of the downstream reaches of seven rivers and adjacent nearshore and offshore waters as far as ∼60 km south of the Fukushima Dai-ichi nuclear power plant (FDNPP) were studied during the high-river-flow period (June-September 2019) and during the period of October 2019 after typhoon Hagibis. Dissolved 137Cs activities in nearshore water were higher than those in rivers and offshore waters, and this distribution was more intensified after the typhoon, indicating the desorption of 137Cs from riverine suspended particles in addition to the ongoing release of contaminated water from the FDNPP and re-entry of radiocesium via submarine groundwater discharge. This scenario is also supported by the reduction of distribution coefficient (Kd) from a geometric mean value of 5.5 × 105 L/kg in rivers to 9.8 × 104 L/kg in nearshore water. The occupation of desorbed 137Cs to the dissolved activity of this nuclide in nearshore water was estimated to be 0.7%-20% (median: 9.7%) during the high-river-flow period, increasing to 1.4%-66% (32.3%) after the typhoon, suggesting that the desorption during the flood period such as typhoons further contributes to the increase in dissolved 137Cs levels in nearshore water.
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Affiliation(s)
- Hyoe Takata
- Institute of Environmental Radioactivity, Fukushima University, Fukushima, Fukushima 960-1296, Japan
| | - Tatsuo Aono
- Center for Advanced Radiation Emergency Medicine, National Institutes for Quantum and Radiological Science and Technology, Fukushima, Fukushima 960-1295, Japan
| | - Michio Aoyama
- Life and Environmental Science,Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
| | - Mutsuo Inoue
- Low Level Radioactivity Laboratory, Kanazawa University, Nomi, Ishikawa 923-1224, Japan
| | - Hideki Kaeriyama
- Fisheries Resources Institute, Japan Fisheries Research and Education Agency, Yokohama, Kanagawa 236-8648, Japan
| | - Shotaro Suzuki
- Fukushima Prefectural Fisheries and Marine Science Research Centre, Iwaki, Fukushima 970-0316, Japan
| | - Tadahiko Tsuruta
- Japan Atomic Energy Agency, Minamisouma, Fukushima 975-0036, Japan
| | - Toshihiro Wada
- Institute of Environmental Radioactivity, Fukushima University, Fukushima, Fukushima 960-1296, Japan
| | - Yoshifumi Wakiyama
- Institute of Environmental Radioactivity, Fukushima University, Fukushima, Fukushima 960-1296, Japan
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15
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Igarashi Y, Onda Y, Wakiyama Y, Konoplev A, Zheleznyak M, Lisovyi H, Laptev G, Damiyanovich V, Samoilov D, Nanba K, Kirieiev S. Impact of wildfire on 137Cs and 90Sr wash-off in heavily contaminated forests in the Chernobyl exclusion zone. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2020; 259:113764. [PMID: 32040987 DOI: 10.1016/j.envpol.2019.113764] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Revised: 12/05/2019] [Accepted: 12/07/2019] [Indexed: 06/10/2023]
Abstract
Wildfires may play a role in redistributing radionuclides in the environment in combination with hydrological processes such as surface runoff and soil erosion. We investigated plot-scale radionuclide wash-off at forest sites affected by wildfires in the Chernobyl Exclusion Zone (CEZ). We also compared speciation of the washed-off radionuclides with those in previous studies conducted just after the accident in 1986. We observed the surface runoff and the radionuclide wash-off with a soil erosion plot at forest and post-fire sites during May-September 2018. In the post-fire site, 2.81 mm of surface runoff was observed in at least three flow events resulting from 285.8 mm total rainfall. The fluxes of dissolved and particulate 137Cs were estimated as 4.9 and 161 Bq m-2, respectively. The dissolved phase 90Sr flux was estimated as 214 Bq m-2. At the forest site, a single surface runoff (0.67 mm) event was generated by rainfall of 182.2 mm. The fluxes of dissolved and particulate 137Cs wash-off values were 6.2 and 8.6 Bq m-2, respectively. The flux of dissolved 90Sr wash-off from the forest was estimated as 45.1 Bq m-2. The distribution coefficient, which indicates the dissolved-particulate form of radionuclides, in the post-fire site was 30 times higher than that in the forest site, indicating the importance of particulate 137Cs wash-off after fire in the CEZ. The entrainment coefficients for dissolved and particulate 137Cs concentrations were around 50 times lower than those obtained in the corresponding position within the CEZ immediately after the accident in 1987. The effect of downward migration of 137Cs over 30 years led to decreased entrainment coefficients for dissolved and particulate 137Cs. The effect of downward migration of radionuclides was considered sufficient to indicate changes in normalized liquid and solid radionuclides wash-off entrainment coefficient and the distribution coefficient in this study.
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Affiliation(s)
- Yasunori Igarashi
- Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima, 960-1296, Fukushima, Japan
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tsukuba, Ibaraki, 305-8572, Japan.
| | - Yoshifumi Wakiyama
- Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima, 960-1296, Fukushima, Japan
| | - Alexei Konoplev
- Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima, 960-1296, Fukushima, Japan
| | - Mark Zheleznyak
- Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima, 960-1296, Fukushima, Japan
| | - Hlib Lisovyi
- Ukrainian Hydrometeorological Institute, Kiev, 03028, Ukraine
| | - Gennady Laptev
- Ukrainian Hydrometeorological Institute, Kiev, 03028, Ukraine
| | - Volodyill Damiyanovich
- Chernobyl Ecocentre, State Agency of Ukraine on Exclusion Zone Management, Chernobyl, 07270, Ukraine
| | - Dmitry Samoilov
- Chernobyl Ecocentre, State Agency of Ukraine on Exclusion Zone Management, Chernobyl, 07270, Ukraine
| | - Kenji Nanba
- Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima, 960-1296, Fukushima, Japan
| | - Serhii Kirieiev
- Chernobyl Ecocentre, State Agency of Ukraine on Exclusion Zone Management, Chernobyl, 07270, Ukraine
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16
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Taniguchi K, Onda Y, Smith HG, Blake W, Yoshimura K, Yamashiki Y, Kuramoto T, Saito K. Transport and Redistribution of Radiocesium in Fukushima Fallout through Rivers. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:12339-12347. [PMID: 31490064 DOI: 10.1021/acs.est.9b02890] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident released the most significant quantity of radiocesium into the environment since Chernobyl, and detailed measurements over the initial 5 years provide new insights into fluvial redistribution of radiocesium. We found that the high initial activity concentration of 137Cs-bearing suspended sediment in rivers was followed by a steep exponential decline (λ1) which extended to approximately 1 year after the accident, while the rate of initial decline in radiocesium activity concentration in water was an order of magnitude higher than rates measured after Chernobyl. Fluvial transport of 137Cs to the ocean from the Abukuma river totaled 12 TBq between June 2011 and August 2015 and almost all this radiocesium (96.5%) was transported in the particulate form. The primary sources of 137Cs were paddy fields, farmland, and urban areas [plaque-forming unit (PFU)], discharging 85% of the exported 137Cs from 38% of the watershed area. After 1 year, activity concentrations were lower and exhibited a more gradual secondary decline (λ2) which was associated with reduced radiocesium losses from PFU areas, while forest areas continue to represent more stable contaminant stores.
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Affiliation(s)
- Keisuke Taniguchi
- Center for Research in Isotopes and Environmental Dynamics , University of Tsukuba , Tsukuba 305-8572 , Japan
- Fukushima Prefectural Centre for Environmental Creation , Miharu 963-7700 , Japan
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics , University of Tsukuba , Tsukuba 305-8572 , Japan
| | - Hugh G Smith
- Landcare Research , Private Bag 11052 , Palmerston North 4442 , New Zealand
| | - William Blake
- School of Geography, Earth and Environmental Sciences , University of Plymouth , Plymouth PL4 8AA , Devon , U.K
| | - Kazuya Yoshimura
- Japan Atomic Energy Agency, Sector of Fukushima Research and Development , 45-169 Sukakeba, Kaihana , Haramachi-ku, Minamisoma 975-0036 , Fukushima , Japan
| | - Yosuke Yamashiki
- Graduate School of Advanced Integrated Studies , Kyoto University , 1 Yoshida-Nakaadachicho , Sakyo, Kyoto 606-8306 , Japan
| | - Takayuki Kuramoto
- Fukushima Prefectural Centre for Environmental Creation , Miharu 963-7700 , Japan
| | - Kimiaki Saito
- Japan Atomic Energy Agency, Nuclear Emergency Assistance and Training Center , 178-4-4 Wakashiba , Kashiwa , Chiba 227-0871 , Japan
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