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Chalaux-Clergue T, Foucher A, Chaboche PA, Hayashi S, Tsuji H, Wakiyama Y, Huon S, Vandromme R, Cerdan O, Nakao A, Evrard O. Impacts of farmland decontamination on 137Cs transfers in rivers after Fukushima nuclear accident: Evidence from a retrospective sediment core study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 947:174546. [PMID: 38992347 DOI: 10.1016/j.scitotenv.2024.174546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 07/03/2024] [Accepted: 07/04/2024] [Indexed: 07/13/2024]
Abstract
Following the Fukushima Daiichi Nuclear Power Plant disaster in March 2011, the Japanese government initiated an unprecedented decontamination programme to remediate 137Cs-contaminated soils and allow population return. This programme involved the removal of topsoil under farmland and residential land, and its replacement with "fresh soil" composed of granitic saprolite. However, decontamination was limited to these two land uses, without remediating forests, which cover 70 % of the surface area in the affected region. In this unprecedented context, the specific impact of this unique decontamination programme on 137Cs transfers in river systems remains to be quantified at the catchment scale. In this study, based on the analysis of a sediment core collected in June 2021 in the Mano Dam reservoir draining a decontaminated catchment, the effects of soil decontamination on particle-bound 137Cs dynamics and sediment source contributions in response to a succession of extreme precipitation events were retrospectively assessed. The sequence of sediment layer deposition and its chronology were reconstructed through the analysis of several diagnostic properties (organic matter, elemental geochemistry, visible colourimetry, granulometry) and contextual information. During abandonment (2011-2016), cropland contribution decreased (31 %). Concurrently, 137Cs activity and deposition flux decreased (19 and 29%year-1, respectively). Following decontamination (2017), sediment transfer increased (270 %) in response to increased contributions from decontaminated cropland and "fresh soil" (625 % and 180 % respectively). Meanwhile, forest contributions remained stable. In contrast, 137Cs activity dropped (65 %), although 137Cs deposition flux remained constant. Forests acted as a stable source of 137Cs. Accordingly, 137Cs deposition flux after decontamination (2016-2021) was similar to that observed during the 5-years period of land abandonment (2011-2016), as a result of the regrowth of spontaneous vegetation over farmland, protecting soil against erosion. Future research should further investigate the impact of longer land abandonment that prevailed in some regions decontaminated lately on the 137Cs fluxes in the rivers.
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Affiliation(s)
- Thomas Chalaux-Clergue
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL), Université Paris-Saclay, UMR 8212 (CEA-CNRS-UVSQ), Gif-sur-Yvette 91190, France.
| | - Anthony Foucher
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL), Université Paris-Saclay, UMR 8212 (CEA-CNRS-UVSQ), Gif-sur-Yvette 91190, France
| | - Pierre-Alexis Chaboche
- International Research Fellow of Japan Society for the Promotion of Science, Postdoctoral Fellowships for Research in Japan (Standard), Japan; Institute of Environmental Radioactivity (IER), University of Fukushima, Fukushima, Japan
| | - Seiji Hayashi
- National Institute for Environmental Science (NIES), Fukushima Branch, 10-2 Fukasaku, Miharu, Tamura, Fukushima 963-7700, Japan
| | - Hideki Tsuji
- National Institute for Environmental Science (NIES), Fukushima Branch, 10-2 Fukasaku, Miharu, Tamura, Fukushima 963-7700, Japan
| | - Yoshifumi Wakiyama
- Institute of Environmental Radioactivity (IER), University of Fukushima, Fukushima, Japan
| | - Sylvain Huon
- Sorbonne Universités UPMC Université Paris 06, Institut d'Ecologie et des Sciences de l'Environnement de Paris (iEES), case 120, 4 place Jussieu, Paris cedex 05 75252, France
| | - Rosalie Vandromme
- Risk and Prevention Division, Bureau de Recherches Géologiques et Minières (BRGM), Orléans F-45060, France
| | - Olivier Cerdan
- Risk and Prevention Division, Bureau de Recherches Géologiques et Minières (BRGM), Orléans F-45060, France
| | - Atsushi Nakao
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Shimogamo, Hangi, Sakyo-ku, Kyoto 606-8522, Japan
| | - Olivier Evrard
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE-IPSL), Université Paris-Saclay, UMR 8212 (CEA-CNRS-UVSQ), Gif-sur-Yvette 91190, France.
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Kawano T, Onda Y, Kato H, Takahashi J. Mechanisms of 137Cs leaching based on long-term observations in forested headwater catchments in Yamakiya, Fukushima Prefecture, Japan. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 907:167837. [PMID: 37839480 DOI: 10.1016/j.scitotenv.2023.167837] [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: 04/08/2023] [Revised: 10/12/2023] [Accepted: 10/12/2023] [Indexed: 10/17/2023]
Abstract
Dissolved radiocesium (mainly 134Cs and 137Cs) is thought to be leached mainly from suspended sediment in downstream rivers, while organic matter, such as leaf litter, contributes to catchments in forested headwater streams. It is also known that dissolved 137Cs in headwater streams exhibit seasonal variation with water temperature. Some mechanisms have been proposed as the causes: ionic competition of potassium ion (K+) and ammonium ion (NH4+), leaching associated with the decomposition of organic matter, and thermodynamic adsorption-desorption processes. We investigated the relationship between K+ and the dissolved organic carbon (DOC) concentrations and seasonal changes in dissolved 137Cs concentration using a large number of samples from a headwater's small catchments. We examined temporal trends in 137Cs concentrations in coarse organic matter, suspended sediments, and dissolved forms at four sites (one decontaminated site and three undecontaminated sites) in the Yamakiya area since 2011. The distribution coefficients (Kdcss and Kdorg) of dissolved 137Cs concentrations relative to suspended sediment and coarse organic matter 137Cs concentrations were calculated, and differences in temporal changes due to decontamination were investigated. In addition, we examined the relationship between water temperature and DOC, K+, NH4+ and 137Cs concentrations in the headwater catchments. The suspended sediment 137Cs concentrations at the decontaminated headwater site (IBO) decreased significantly after decontamination and remained low thereafter. In contrast, dissolved 137Cs concentrations decreased temporarily during the decontamination period, but returned to pre-decontamination levels. Almost no NH4+ has been detected in headwater streams in our catchments. In the SET and ISH watersheds, where the distance from the groundwater spring is short, a correlation was found between DOC concentration and dissolved 137Cs concentration. In contrast, in the IBO watershed, where the distance from the groundwater spring is long, temperature dependence and a good correlation between K+ and 137Cs were observed. Therefore, microbial decomposition of organic matter may have a significant effect on the seasonal variation of dissolved 137Cs in forested headwater streams at short distances from the spring, but the influence of competing ions is expected to increase gradually as the water flows downstream.
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Affiliation(s)
- Taichi Kawano
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan
| | - Yuichi Onda
- Center for Research in Radiation, Isotopes and Earth System Sciences, University of Tsukuba, Japan.
| | - Hiroaki Kato
- Center for Research in Radiation, Isotopes and Earth System Sciences, University of Tsukuba, Japan
| | - Junko Takahashi
- Center for Research in Radiation, Isotopes and Earth System Sciences, University of Tsukuba, Japan
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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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Liu Y, Zhou Z, Gong W, Xu Y, Ding Q, Cui L. Distribution, risk assessment of heavy metals in sediments, and their potential risk on water supply safety of a drinking water reservoir, middle China. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023:10.1007/s11356-023-26917-2. [PMID: 37195608 DOI: 10.1007/s11356-023-26917-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 04/05/2023] [Indexed: 05/18/2023]
Abstract
Heavy metals in reservoir sediments were analyzed to assess the pollution level and to understand the potential risk on water supply safety. Heavy metals in sediments will enter the biological chain through bio-enrichment and bio-amplification in water and eventually pose a threat to the safety of drinking water supply. Analysis of eight sampling sites in JG (Jian gang) drinking water reservoir of the sediments showed that from Feb 2018 to Aug 2019 heavy metals including Pb, Ni, Cu, Zn, Mo, and Cr increased by 1.09-17.2%. Vertical distributions of heavy metals indicated that the concentrations increased gradually by 9.6-35.8%. Risk assessment code analysis indicated that Pb, Zn, and Mo were of high risk in the main reservoir area. What is more, enrichment factors of Ni and Mo were 2.76-3.81 and 5.86-9.41, respectively, showing the characteristics of exogenous input. The continuous monitoring results of the bottom water showed that the concentration of heavy metals in the bottom water exceeded the environmental quality standard value of surface water in China, and exceeded the standard by 1.76 times (Pb), 1.43 times (Zn), and 2.04 times (Mo), respectively. Heavy metals in the sediments of JG Reservoir, especially in the main reservoir area, have a potential risk of release from the sediment to the overlying water. Water supply reservoir as a source of drinking water, its quality is directly related to human health and production activities. Therefore, this first study on JG Reservoir is of great significance for the protection of drinking water safety and human health.
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Affiliation(s)
- Yupei Liu
- School of Energy and Environment, Zhongyuan University of Technology, Zhengzhou, 450007, China
| | - Zizhen Zhou
- School of Energy and Environment, Zhongyuan University of Technology, Zhengzhou, 450007, China.
| | - Weijin Gong
- School of Energy and Environment, Zhongyuan University of Technology, Zhengzhou, 450007, China
| | - Yu Xu
- School of Energy and Environment, Zhongyuan University of Technology, Zhengzhou, 450007, China
| | - Qian Ding
- School of Energy and Environment, Zhongyuan University of Technology, Zhengzhou, 450007, China
| | - Lu Cui
- School of Energy and Environment, Zhongyuan University of Technology, Zhengzhou, 450007, China
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Sakai M, Ishii Y, Tsuji H, Tanaka A, Jo J, Negishi JN, Hayashi S. Contrasting seasonality of 137Cs concentrations in two stream animals that share a trophic niche. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 315:120474. [PMID: 36270568 DOI: 10.1016/j.envpol.2022.120474] [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: 06/20/2022] [Revised: 09/28/2022] [Accepted: 10/15/2022] [Indexed: 06/16/2023]
Abstract
Understanding the seasonality of 137Cs concentrations in aquatic animals is crucial for reviving local inland fisheries. The seasonality of 137Cs concentrations in animals is expected to vary, even if focal species consume similarly contaminated foods because the 137Cs excretion rate is species-specific, and 137Cs uptake by foraging autochthonous food resources also vary among seasons. Here, we conducted a seasonal monitoring survey of dissolved 137Cs concentrations as an indicator of the contamination level of food resources and measured 137Cs concentrations in two carnivorous aquatic animals (Palaemon paucidens and Rhinogobius sp.) that share a trophic niche in a stream connected to a dam reservoir. The dissolved 137Cs concentration had clear seasonality-high in summer and low in winter. The 137Cs concentrations in the animals revealed a different seasonal pattern-it peaked in October in P. paucidens and peaked in February in Rhinogobius. Overall, the 137Cs concentration was relatively higher in P. paucidens than in Rhinogobius, suggesting that P. paucidens has a lower excretion rate than Rhinogobius. Consequently, the seasonality of the 137Cs concentration in P. paucidens showed temporal changes similar to those of the dissolved 137Cs concentration, which were likely affected by 137Cs uptake through foraging, whereas that in Rhinogobius was controlled by 137Cs excretion. This study shows that the seasonality of 137Cs concentration can differ between sympatric animals that share a trophic niche. Accumulating knowledge and comparing the seasonality of 137Cs concentrations in fisheries species based on the balance between uptake and excretion will be valuable to determine the appropriate seasons to obtain less-contaminated products.
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Affiliation(s)
- Masaru Sakai
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan.
| | - Yumiko Ishii
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan
| | - Hideki Tsuji
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan
| | - Asuka Tanaka
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan
| | - Jaeick Jo
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan
| | - Junjiro N Negishi
- Faculty of Environmental Earth Science, Hokkaido University, Kita 10, Nishi 5, Kita-ku, Sapporo, Hokkaido, 060-0810, Japan
| | - Seiji Hayashi
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies, 10-2 Fukasaku, Miharu, Tamura District, Fukushima, Tamura District, 963-7700, Japan
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