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Okhrimchuk D, Hurtevent P, Gonze MA, Simon-Cornu M, Roulier M, Carasco L, Orjollet D, Nicolas M, Probst A. Long-term behaviour of Cs-137, Cs-133 and K in beech trees of French forests. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2024; 277:107450. [PMID: 38762981 DOI: 10.1016/j.jenvrad.2024.107450] [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: 01/29/2024] [Revised: 04/04/2024] [Accepted: 05/12/2024] [Indexed: 05/21/2024]
Abstract
In the long-term after atmospheric deposit onto a forest ecosystem, Cs-137 becomes incorporated into the biogeochemical cycle of stable elements and progressively reaches a quasi-equilibrium state. This study aimed at determining to what extent Cs-137 activity distribution in tree vegetation could be predicted from that of stable caesium (Cs-133) and potassium (K), which are known to be stable chemical analogues and competitors for Cs-137 intake in tree organs. Field campaigns that focused on beech trees (Fagus sylvatica L.) were conducted in 2021 in three French forest stands with contrasted characteristics regarding either the contribution of global vs. Chornobyl fallouts, soil or climatic conditions. Decades after Cs-137 fallouts, it was found that more than 80% of the total radioactive inventory in the system remained confined in the top 20 cm mineral layers, while organic layers and beech vegetation (including roots) contributed each to less than 1.5%. The enhanced downward migration of Cs-137 in cambisol than podzol forest sites was presumably due to migration of clay particles and bioturbation. The distribution of Cs-137 and Cs-133 inventories in beech trees was very similar among sites but differed from that of K due a higher accumulation of Cs isotopes in roots (40-50% vs. < 25% for K). The aggregated transfer factor (Tag) of Cs-137 calculated for aerial beech organs were all lower than those reported in literature more than 20 years ago, this suggesting a decrease of bioavailability in soil due to ageing processes. Regarding their variability, Tags were generally lower by a factor 5 at the cambisol site, which was fairly well explained by a much higher value of RIP (radiocesium immobilisation potential). Cs-137 concentrations in trees organs normalized by the soil exchangeable fractions were linearly correlated to those of Cs-133 and the best fit was found for the linear regression model without intercept indicating that no more contribution of the foliar uptake could be observed on long term. Provided that the vertical distribution of caesium concentrations and fine root density are properly measured or estimated, Cs-133 was shown to be a much better proxy than K to estimate the root transfer of Cs-137.
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Affiliation(s)
- D Okhrimchuk
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SERPEN/LEREN, PSE-ENV/SPDR/LT2S, PSE-ENV/STAAR/LRTA, F-13115 Saint-Paul-lez-Durance, France
| | - P Hurtevent
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SERPEN/LEREN, PSE-ENV/SPDR/LT2S, PSE-ENV/STAAR/LRTA, F-13115 Saint-Paul-lez-Durance, France.
| | - M-A Gonze
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SERPEN/LEREN, PSE-ENV/SPDR/LT2S, PSE-ENV/STAAR/LRTA, F-13115 Saint-Paul-lez-Durance, France
| | - M Simon-Cornu
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SERPEN/LEREN, PSE-ENV/SPDR/LT2S, PSE-ENV/STAAR/LRTA, F-13115 Saint-Paul-lez-Durance, France
| | - M Roulier
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SERPEN/LEREN, PSE-ENV/SPDR/LT2S, PSE-ENV/STAAR/LRTA, F-13115 Saint-Paul-lez-Durance, France
| | - L Carasco
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SERPEN/LEREN, PSE-ENV/SPDR/LT2S, PSE-ENV/STAAR/LRTA, F-13115 Saint-Paul-lez-Durance, France
| | - D Orjollet
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SERPEN/LEREN, PSE-ENV/SPDR/LT2S, PSE-ENV/STAAR/LRTA, F-13115 Saint-Paul-lez-Durance, France
| | - M Nicolas
- ONF/Département Recherche-Développement-Innovation, F-77330, Fontainebleau, France
| | - A Probst
- CRBE (Centre de Recherche sur la Biodiversité et l'Environnement), Université de Toulouse, CNRS, IRD, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UT3), F-31062, Toulouse, France
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Tanaka T, Thiry Y. How dynamic transfer models can complement an equilibrium-based approach: Case studies of radiocesium transfer to forest trees following accidental atmospheric release. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 884:163715. [PMID: 37137358 DOI: 10.1016/j.scitotenv.2023.163715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/18/2023] [Accepted: 04/20/2023] [Indexed: 05/05/2023]
Abstract
Accidental release of radionuclides caused by nuclear accidents like those in Fukushima and Chernobyl can result in pulses of radioactivity entering the forest environment. Due to intense recycling in the forest, equilibrium between radioactivity concentrations in trees and in soil may not be reached during the period of severe short-term radionuclide transport following the accident. Another question arises as to whether the equilibrium hypothesis using empirical concentration ratios (CRs) can be applied to the long-term period. Using two atmospheric 137Cs fallout scenarios in the Fukushima and Chernobyl sites, this study investigated whether the CR approach could provide conservative predictions of 137Cs levels in trees following 137Cs fallout events by comparing predictions from the CR approach using data gathered for trees by the IAEA to those from dynamic transfer models and actual measured data. The inter-comparisons also aimed to investigate whether the CR approach could account for the variability of 137Cs levels across different tree organs. The results showed that caution may be necessary when using the CR approach, which relies on the IAEA dataset, to estimate 137Cs accumulation in forest trees in the short - and long term following atmospheric 137Cs fallout events. A calculation by TRIPS 2.0 demonstrated the importance of considering the distribution within tree organs for in-depth analysis of radiological impact of forest trees. Our findings suggest that it may be preferable to use CR values based on site-specific data rather than generic data collected from various sites. This is particularly relevant when studying the sites where the bioavailability of 137Cs for trees and thus possible exposures are higher. This study also showed that dynamic modeling approaches could offer an alternative means of estimating CR values of the entire tree or specific tree organs in situations where empirically derived values are not available.
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Affiliation(s)
- Taku Tanaka
- EDF R&D, LNHE, 6 Quai Watier, 78400 Chatou, France.
| | - Yves Thiry
- French National Radioactive Waste Management Agency (Andra) - Research and Development Division, 92298 Chatenay-Malabry, France
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Saidin ZH, Levia DF, Kato H, Kurihara M, Hudson JE, Nanko K, Onda Y. Vertical distribution and transport of radiocesium via branchflow and stemflow through the canopy of cedar and oak stands in the aftermath of the Fukushima Dai-ichi Nuclear Power Plant accident. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 818:151698. [PMID: 34798091 DOI: 10.1016/j.scitotenv.2021.151698] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Revised: 11/11/2021] [Accepted: 11/11/2021] [Indexed: 06/13/2023]
Abstract
Aiming to fill a need for data regarding radiocesium transport via both branchflow and stemflow through forests impacted by radioactive fallout, this study examined the vertical variation of radiocesium flux from branchflow and stemflow through the canopies of young Japanese cedar (Cryptomeria japonica (L. f.) D. Don) and Japanese oak (Quercus serrata Murray) trees in the aftermath of the Fukushima Dai-ichi Nuclear Power Plant accident. In forested areas approximately 40 km northwest of the location of the Fukushima Dai-ichi accident, the 137Cs concentration varied significantly among sampling periods and between the two forests, with the oak stand exhibiting higher 137Cs concentrations and depositional fluxes than the cedar stand. Expressed per unit trunk basal area, the depositional flux of 137Cs generated from the cedar and oak stands was 375 and 2810 Bq m-2 year-1, respectively. Of this total, 71% and 48% originated from the cedar and oak canopy, respectively, while the remainder originated from the trunk. Accordingly, the origin of radiocesium was more balanced for the oak stand with almost half of the flux coming from the canopy (48%) and the other half from the trunk (52%). Only about a quarter (29%) of the radiocesium flux originated from the trunk in Japanese cedar. Results from this work provide needed data that can enable a more thorough conceptualization of radiocesium cycling in forests. Coupling these empirical results with a physically-based model would likely lead to better forest management and proactive strategies for rehabilitating radioactively-contaminated forests and reducing the exposure risk of radiation dose rate for those that utilize forest products.
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Affiliation(s)
- Zul Hilmi Saidin
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Delphis F Levia
- Department of Geography and Spatial Sciences, University of Delaware, Newark, DE, USA; Department of Plant and Soil Sciences, University of Delaware, Newark, DE, USA
| | - Hiroaki Kato
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Momo Kurihara
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Janice E Hudson
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Kazuki Nanko
- Department of Disaster Prevention, Meteorology and Hydrology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, Japan
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tsukuba, Ibaraki, Japan.
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Ota M, Koarashi J. Contamination processes of tree components in Japanese forest ecosystems affected by the Fukushima Daiichi Nuclear Power Plant accident 137Cs fallout. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 816:151587. [PMID: 34838924 DOI: 10.1016/j.scitotenv.2021.151587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/30/2021] [Accepted: 11/06/2021] [Indexed: 06/13/2023]
Abstract
In forests affected by the Fukushima Daiichi Nuclear Power Plant accident, trees became contaminated with 137Cs. However, 137Cs transfer processes determining tree contamination (particularly for stem wood, a prominent commercial resource) remain insufficiently understood. We propose a model for simulating dynamic behavior of 137Cs in a forest tree-litter-soil system and applied it to contaminated forests of cedar plantation and natural oak stand in Fukushima to elucidate relative impact of distinct 137Cs transfer processes determining the tree contamination. The transfer of 137Cs to the trees occurred mostly (>99%) through surface uptake of 137Cs trapped by needles and bark during the fallout. Root uptake of soil 137Cs was several orders of magnitude lower than the surface uptake over a 50-year period following the accident. As a result, internal contamination of the trees proceeded through an enduring recycling (translocation) of 137Cs absorbed on the tree surface. A significant surface uptake of 137Cs through bark was suggested, contributing to 100% (leafless oak tree) and 30% (foliated cedar tree; the remaining uptake occurred at needles) of the total uptake by the trees, although that pathway still needs to be evaluated by experimental evidence. It was suggested that the activity concentration of 137Cs in stem wood of the trees at these sites are currently (as of 2021) decreasing by ~3% per year, mainly through radioactive decay of 137Cs and partly through dilution effect from tree growth. Although further refinement of the model is recommended, for example by including tree species specific 137Cs transportation in stem, these findings provide vital information for planning of forestry reactivation in Fukushima; e.g., removal of forest floor organic layer will not reduce the tree contamination for a long term because of the 137Cs absorption via the tree surface substantially greater than root uptake of 137Cs deposited to the floor.
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Affiliation(s)
- Masakazu Ota
- Research Group for Environmental Science, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan.
| | - Jun Koarashi
- Research Group for Environmental Science, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan
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Imamura N, Watanabe M, Manaka T. Estimation of the rate of 137Cs root uptake into stemwood of Japanese cedar using an isotopic approach. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 755:142478. [PMID: 33045609 DOI: 10.1016/j.scitotenv.2020.142478] [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: 05/12/2020] [Revised: 09/16/2020] [Accepted: 09/16/2020] [Indexed: 06/11/2023]
Abstract
Japanese cedar (Cryptomeria japonica) is the main timber species in Japan. The prediction of the temporal changes in the 137Cs concentration in the stemwood of Japanese cedar after the Fukushima nuclear accident is essential for optimizing forest management in contaminated areas. However, it is difficult to estimate the respective contributions of root and foliar uptake to 137Cs accumulation in stemwood from simple field measurements, especially in trees that contain the residue of initially-deposited 137Cs. In this study, we devised a method for estimating the rate of 137Cs root uptake into stemwood using the 133Cs content in stemwood and the 137Cs/133Cs ratio in the exchangeable fraction of soil. As a trial, the method was applied to a cedar stand in Fukushima Prefecture, using available monitoring data from prior studies over 5 years from August 2011 to August 2016. The mean annual rate of 137Cs root uptake into stemwood over this period was estimated as 53 ± 20 Bq m-2 yr-1. We note that our method likely provided a maximum estimate, because it is based on the assumptions that 133Cs in wood is exclusively supplied by root uptake, and that Cs isotopes are taken up by roots in the top 5 cm of mineral soil. Moreover, the mean annual increase of the 137Cs inventory in stemwood during the study period was measured as 108 Bq m-2 yr-1, although this value was associated with considerable uncertainty (95% confidence interval from -109 to 324 Bq m-2 yr-1). As a result, the maximum estimated rate of 137Cs root uptake into stemwood accounted for around half of the measured rate of 137Cs accumulation in stemwood. Our results show that the Cs isotopic approach has potential to distinguish the main pathway of stemwood contamination (i.e., root vs. foliar uptake) following radioactive fallout.
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Affiliation(s)
- Naohiro Imamura
- Department of Forest Soils, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Mirai Watanabe
- Center for Regional Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
| | - Takuya Manaka
- Department of Forest Soils, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
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6
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Imamura N, Komatsu M, Hashimoto S, Fujii K, Kato H, Thiry Y, Shaw G. Vertical distributions of radiocesium in Japanese forest soils following the Fukushima Daiichi Nuclear Power Plant accident: A meta-analysis. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 225:106422. [PMID: 32980644 DOI: 10.1016/j.jenvrad.2020.106422] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 09/08/2020] [Accepted: 09/08/2020] [Indexed: 06/11/2023]
Abstract
This study investigated the temporal change in vertical distributions of radiocesium inventories in Japanese forest soils during the early phase (from 2011 to 2017) following the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, using three simple parameters. We calculated the fraction in the organic layer (Fl/t), the migration center (Xc) and the relaxation depth (α) using 99 soil inventory data sets. Fl/t decreased significantly from 2011 to 2017 (logistic analysis, p < 0.001). In addition, Fl/t in the FDNPP zone rapidly decreased compared to that in the Chernobyl Nuclear Power Plant (ChNPP) zone from the first year to the second year. Different migration rates from organic to mineral soil layers between previous studies in the ChNPP and this study have several possible causes such as organic litter features, climate and physico-chemical forms of initial deposition. In mineral soil layers in the FDNPP zone, only Xc increased significantly with time according to generalized mixed model analysis (p < 0.01). However, Xc and α in the ChNPP zone decreased from two to five years after the accident in 1986, which shows a high 137Cs retention in the organic layer even in the fifth year after the accident. The vertical migration of 137Cs in the mineral soil layer in the FDNPP zone appears to be due to low input of 137Cs from organic to surface mineral soil layer after the second year. These results indicate that 137Cs retention capacity of the organic layer can affect the apparent vertical migration of 137Cs in the underlying mineral soil layer.
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Affiliation(s)
- Naohiro Imamura
- Department of Forest Soils, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan.
| | - Masabumi Komatsu
- Department of Mushroom Science and Forest Microbiology, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Shoji Hashimoto
- Department of Forest Soils, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan; Isotope Facility for Agricultural Education and Research, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi 1-1-1 Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Kazumichi Fujii
- Department of Forest Soils, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Hiroaki Kato
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tennoudai 1-1-1, Tsukuba, Ibaraki, 305-0006, Japan
| | - Yves Thiry
- Research and Development Division, National Radioactive Waste Management Agency (Andra), 1-7 Rue Jean-Monnet, 92298, Châtenary-Malabry Cedex, France
| | - George Shaw
- School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD, UK
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Spatial variation and radiocesium flux of litterfall in hardwood-pine mixed forest and cedar plantations based on long-term monitoring data. J Radioanal Nucl Chem 2020. [DOI: 10.1007/s10967-020-07433-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Babić D, Skoko B, Franić Z, Senčar J, Šoštarić M, Petroci L, Avdić M, Kovačić M, Branica G, Petrinec B, Bituh T, Franulović I, Marović G. Baseline radioecological data for the soil and selected bioindicator organisms in the temperate forest of Plitvice Lakes National Park, Croatia. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:21040-21056. [PMID: 32266621 DOI: 10.1007/s11356-020-08369-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 03/09/2020] [Indexed: 06/11/2023]
Abstract
The aim of this study was to provide baseline radioecological data for the temperate forest ecosystem in Plitvice Lakes National Park. Emphasis was placed on the determination of naturally occurring radionuclides since there is an acknowledged lack of data for these radionuclides in non-accident conditions in wildlife, even for bioindicator organisms. Activity concentrations of 238U, 226Ra, 210Pb, 232Th, 40K, 134Cs, and 137Cs were measured by gamma spectrometry in soil and bioindicators: earthworms, conifer needles, mosses, and lichens. From the measured activity concentrations, concentration ratios were calculated to quantify the transfer of these radionuclides from soil to bioindicators. Our results show that soil activity concentrations are biased toward results from other studies conducted within the Dinaric mountain region. However, in moss and lichen samples, we measured higher activity concentrations of 226Ra and lower activity concentrations of 40K and 137Cs in comparison to similar studies. Also, we estimated lower concentration ratios for all radionuclides from soil to these organisms, except for 210Pb, in comparison to generic values. The transfer of 238U was generally low for all of the bioindicator organisms. For conifer needles, a correlation was found between activity concentrations of 226Ra and 137Cs in soil and related concentration ratios. Correlation was also found between the activity concentration of 40K in soil and transfer of 40K and 137Cs to mosses and lichens. A comparison with literature data highlighted the lack of 226Ra related concentration ratios for conifer trees and especially for earthworms. Therefore, the results of this study could supplement the sparse data currently available on radionuclide background data in similar ecosystems and related soil-to-wildlife transfer of radionuclides. Dose rate assessments, performed by the ERICA Tool, estimated that 96% of the overall exposure of wildlife in the Park area is due to the background dose rates, while 0.06 μGy h-1 on average can be attributed as an incremental dose rate from 134Cs and 137Cs.
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Affiliation(s)
- Dinko Babić
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
| | - Božena Skoko
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia.
| | - Zdenko Franić
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
| | - Jasminka Senčar
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
| | - Marko Šoštarić
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
| | - Ljerka Petroci
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
| | - Mak Avdić
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
| | - Milica Kovačić
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
| | - Gina Branica
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
| | - Branko Petrinec
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
| | - Tomislav Bituh
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
| | - Iva Franulović
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
| | - Gordana Marović
- Institute for Medical Research and Occupational Health, Ksaverska cesta 2, HR-10000, Zagreb, Croatia
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Thiry Y, Tanaka T, Dvornik AA, Dvornik AM. TRIPS 2.0: Toward more comprehensive modeling of radiocaesium cycling in forest. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 214-215:106171. [PMID: 32063289 DOI: 10.1016/j.jenvrad.2020.106171] [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: 12/05/2019] [Revised: 01/14/2020] [Accepted: 01/14/2020] [Indexed: 06/10/2023]
Abstract
Because internal transfers can play a key role in radiocaesium persistence in trees, a reliable representation of radiocaesium recycling between tree organs in forest models is important for long-term simulations after radioactive fallout in Chernobyl and Fukushima. We developed an upgraded 2.0 version of the initial TRIPS ("Transfer of Radionuclides In Perennial vegetation System") model involving explicit differentiation between tree organs (i.e., foliage, branches, stemwood and bark). The quality of TRIPS 2.0 was evaluated by testing model outputs against independent datasets for pine stands in Belarus and Ukraine. Scenarios involving "hot particle" deposits in forest remained challenging, but in all other scenarios generally positive verification results for soil and tree compartments indicated that the TRIPS 2.0 model adequately combines the major relevant processes. Interestingly, the response of stemwood contamination to changes in radiocaesium availability in soil, as determined by soil conditions, was shown to be more sensitive than for other tree compartments. We recommend the conceptual tree discretization of TRIPS 2.0 for generic forest modeling for two reasons: 1) regardless of different soil conditions, there was concurrent good agreement between simulations and data for individual tree compartments (foliage, branches, stemwood and bark), and 2) the measurements necessary to estimate internal tree transfers are easily accessible to usual field monitoring in forest biogeochemistry (for details, see Goor, F. & Thiry, Y., 2004. Science of the total environment, 325(1-3), 163-180).
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Affiliation(s)
- Y Thiry
- French National Radioactive Waste Management Agency (Andra) - Research and Development Division, 92298, Chatenay-Malabry, France.
| | - T Tanaka
- EDF R&D, LNHE, 6 Quai Watier, 78400, Chatou, France.
| | - A A Dvornik
- Institute of Radiobiology of National Academy of Sciences of Belarus, 4, Fedjuninskogo Str., 246007, Gomel, Belarus.
| | - A M Dvornik
- Gomel State University, Sovetskaya St.104, 246019, Gomel, Belarus.
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Hara T, Takenaka C, Tomioka R. Change in the chemical form of 137Cs with age in needles of Japanese cedar. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 213:106137. [PMID: 31983446 DOI: 10.1016/j.jenvrad.2019.106137] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/21/2019] [Accepted: 12/10/2019] [Indexed: 06/10/2023]
Abstract
Radiocesium (137Cs) derived from the accident of Fukushima Dai-ichi Nuclear Power Plant remains in forests. Although a large proportion of the 137Cs in forests has been transferred to soils, the rates of transfer to soils depend on the chemical form of 137Cs, which determines the mobility of 137Cs in plant tissues and subsequently during decomposition of leaf litter. In order to understand the dynamics of 137Cs in Sugi (Japanese cedar, Cryptomeria japonica) forests, we identified the chemical forms, such as water soluble, ion-exchangeable, and residual of 137Cs, 133Cs, K, and Rb in needle-bearing Sugi branches of different ages across several years. Compared with the results for K and Rb, Cs (133Cs + 137Cs) tended to change from a water-soluble form to an immobilized form with aging of needle-bearing branch segments. In addition, it was observed that a larger proportion of the immobilized Cs were accumulated in the green outer portions of the stems through aging.
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Affiliation(s)
- Tatsuya Hara
- Graduate School of Bioagricultural Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
| | - Chisato Takenaka
- Graduate School of Bioagricultural Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
| | - Rie Tomioka
- Graduate School of Bioagricultural Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan
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Hashimoto S, Imamura N, Kaneko S, Komatsu M, Matsuura T, Nishina K, Ohashi S. New predictions of 137Cs dynamics in forests after the Fukushima nuclear accident. Sci Rep 2020; 10:29. [PMID: 31913315 PMCID: PMC6949301 DOI: 10.1038/s41598-019-56800-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 10/30/2019] [Indexed: 11/13/2022] Open
Abstract
Most of the area contaminated by the Fukushima Daiichi Nuclear Power Plant accident is covered by forest. In this paper, we updated model predictions of temporal changes in the 137Cs dynamics using the latest observation data and newly provided maps of the predicted 137Cs activity concentration for wood, which is the most commercially important part of the tree body. Overall, the previous prediction and latest observation data were in very good agreement. However, further validation revealed that the migration from the soil surface organic layer to the mineral soil was overestimated for evergreen needleleaf forests. The new prediction of the 137Cs inventory showed that although the 137Cs distribution within forests differed among forest types in the first 5 years, the difference diminished in the later phase. Besides, the prediction of the wood 137Cs activity concentrations reproduced the different trends of the 137Cs activity concentrations for cedar, oak, and pine trees. Our simulation suggests that the changes of the wood 137Cs activity concentration over time will slow down after 5–10 years. Although the model uncertainty should be considered and monitoring and model updating must continue, the study provides helpful information on the 137Cs dynamics within forest ecosystems and the changes in wood contamination.
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Affiliation(s)
- Shoji Hashimoto
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan. .,Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Naohiro Imamura
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Shinji Kaneko
- Kansai Research Center, Forestry and Forest Products Research Institute, Fushimi, Kyoto, 612-0855, Japan
| | - Masabumi Komatsu
- Department of Mushroom Science and Forest Microbiology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Toshiya Matsuura
- Department of Forest Management, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Kazuya Nishina
- Center for Regional Environmental Research, National Institute for Environmental Studies, Tsukuba, 305-8506, Japan
| | - Shinta Ohashi
- Department of Wood Properties and Processing, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
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Kato H, Onda Y, Saidin ZH, Sakashita W, Hisadome K, Loffredo N. Six-year monitoring study of radiocesium transfer in forest environments following the Fukushima nuclear power plant accident. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 210:105817. [PMID: 30236975 DOI: 10.1016/j.jenvrad.2018.09.015] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 07/25/2018] [Accepted: 09/09/2018] [Indexed: 06/08/2023]
Abstract
The study investigated temporal changes in the 137Cs concentrations in vegetal and hydrological samples collected from various forests in Yamakiya District, Kawamata Town of Fukushima prefecture over six years following the Fukushima Dai-ichi nuclear power plant accident. Cesium-137 was detected in all forest environmental samples. However, the concentration in most samples decreased exponentially with time. The 137Cs concentrations in throughfall samples exhibited a double-exponential decreasing trend with time. Temporal changes in the 137Cs concentration in vegetal samples and stemflow were approximated by using a single-exponential equation. A comparison of the decline coefficient for the latter observation period (>2 y since the accident) revealed that the declining trend of 137Cs concentrations varied between foliage and the outer barks of the Japanese cedar and Japanese konara oak trees. The 137Cs concentration in cedar needles decreased exponentially while that in konara oak leaves was constant over the last six years. Conversely, the declining trend of 137Cs concentration in the outer bark of konara oak exceeded that of cedar. The results suggested that self-decontamination processes and internal recycling of 137Cs varied among tree species and different tree parts. The results indicated that the leaching of 137Cs in the throughfall in Japanese cedar was dependent on the 137Cs concentration in needles. However, a comparison of 137Cs concentrations in vegetal and hydrological samples from each sampling year showed that the leaching rate decreased with time. Conversely, the 137Cs concentrations in the stemflow were independent of the concentrations in the outer bark. The declining trend of 137Cs concentrations in litterfall (λ: 0.31-0.33 y-1) was similar to that of the mean of new/old needles (λ: 0.26-0.33 y-1) for cedar stands. With respect to the hydrological components, the 137Cs concentration in the stemflow (λ: 0.32-0.33 y-1) decreased at a slightly slower rate than that in the throughfall (λ: 0.36-0.54 y-1) for the cedar forest. The decline coefficients of 137Cs concentration in the aforementioned types of hydrological components slightly exceeded that for the vegetal samples. The results suggest that monitoring of 137Cs concentrations in hydrological components and vegetal samples can aid in further understanding the leaching mechanisms of 137Cs from trees to rainwater.
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Affiliation(s)
- Hiroaki Kato
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Japan.
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Japan
| | - Zul Hilmi Saidin
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Japan
| | - Wataru Sakashita
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Japan
| | | | - Nicolas Loffredo
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Japan
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Yoshihara T, Yoschenko V, Watanabe K, Keitoku K. A through year behavior of 137Cs in a Japanese flowering cherry tree in relation to that of potassium. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 202:32-40. [PMID: 30776701 DOI: 10.1016/j.jenvrad.2019.01.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 01/09/2019] [Accepted: 01/24/2019] [Indexed: 06/09/2023]
Abstract
To understand the transfer of radiocesium (137Cs) in inside of deciduous trees, changes in 137Cs activity concentrations, primarily derived from the Fukushima accident in March 2011, were observed in the upper parts of a Japanese flowering cherry tree (Prunus x yedoensis cv. Somei-Yoshino) between 2015 and 2018. The sampling of the foliar parts occurred over the entire leaf life span from winter bud to litterfall and those of the branches were distinguished based on emergence years (2017, 2016, 2015, 2014-2011, and 2010/before). First, every tissue demonstrated a clear seasonal variation in 137Cs activity concentration. Second, a synchrony of seasonal variations in 137Cs activity concentration with those in the biological analogue of K concentration was observed in foliar parts during their growth season, but not in branches nor during the other seasons. With respect to the timing of changes in each tissue with tree phenology, it is possible that K and 137Cs alternate between leaves and branches via the same translocation mechanisms. The resorption efficiencies (i.e., 1 - [the concentrations in the last litterfall]/[the maximum concentrations in green leaves]) of K and 137Cs were 76% and 46% in average, respectively. In addition, both leaf buds and branches played an important role as reservoirs during dormancy. The buds storage ratio before and after bud burst (i.e., [the inventories in buds at the end of defoliation]/[those before and after bud burst]) for K were 0.57 and 0.10 in median, respectively, and those for and 137Cs were 1.14 and 0.14 in median, respectively. Consequently, the transfer of 137Cs in inside of trees was still visible seven years after deposition, even though the annual reduction in 137Cs activity concentration was apparent in each tissue.
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Affiliation(s)
- Toshihiro Yoshihara
- Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba, 270-1194, Japan.
| | - Vasyl Yoschenko
- Institute of Environmental Radioactivity of Fukushima University (IER), 1 Kanayagawa, Fukushima, Fukushima, 960-1296, Japan
| | - Kenji Watanabe
- Institute of Environmental Radioactivity of Fukushima University (IER), 1 Kanayagawa, Fukushima, Fukushima, 960-1296, Japan
| | - Koji Keitoku
- Institute of Environmental Radioactivity of Fukushima University (IER), 1 Kanayagawa, Fukushima, Fukushima, 960-1296, Japan; Minamisoma City Hall, Odaka Ward Community Promotion Division, 2-28 Moto-machi Odaka, Minami Soma, Fukushima, 979-2195, Japan
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14
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Nishikiori T, Watanabe M, Koshikawa MK, Watanabe K, Yamamura S, Hayashi S. 137Cs transfer from canopies onto forest floors at Mount Tsukuba in the four years following the Fukushima nuclear accident. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 659:783-789. [PMID: 31096408 DOI: 10.1016/j.scitotenv.2018.12.359] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 12/21/2018] [Accepted: 12/23/2018] [Indexed: 06/09/2023]
Abstract
This study investigated the transport of 137Cs within a forest ecosystem by examining temporal changes in the inventory and determining the major pathways of transfer following significant atmospheric deposition. A forested area of eastern Japan was monitored for four years immediately after the Fukushima nuclear power plant accident in March 2011 that released a large amount of radionuclides. The long physical half-life of 137Cs means that contamination can persist for decades, so it is vital to understand the mechanisms underlying the 137Cs dynamics in ecosystems. We sampled litterfall, throughfall, and soil, mainly from a cedar stand, over a four-year period, and analyzed the 137Cs concentrations of each sample to determine the transfer rate and total inventory. After validating our methodology through a comparison with results from an earlier study, we determined the temporal changes in the 137Cs distribution and in the major transfer pathway. Results showed that most 137Cs intercepted by canopies was transferred rapidly over the first nine months, and that the major pathway was not litterfall but throughfall. The ecological half-life of the 137Cs stocked in the canopy was calculated for both the early and later stages of contamination. Although the former is consistent with previous results, the latter ecological half-life is somewhat longer, probably because of dependence on the meteorological and tree physiological conditions at the site. This study presents valuable new data on the post-Fukushima 137Cs contamination, enhancing our understanding of the associated dynamics in forest ecosystems.
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Affiliation(s)
- Tatsuhiro Nishikiori
- Center for Regional Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan; Agricultural Radiation Research Center, Tohoku Agriculture Research Center, National Agriculture and Food Research Organization, 50 Harajukuminami, Arai, Fukushima, Fukushima 960-2156, Japan
| | - Mirai Watanabe
- Center for Regional Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
| | - Masami K Koshikawa
- Center for Regional Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Keiji Watanabe
- Center for Regional Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Shigeki Yamamura
- Center for Regional Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Seiji Hayashi
- Center for Regional Environmental Research, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
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15
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Thiry Y, Albrecht A, Tanaka T. Development and assessment of a simple ecological model (TRIPS) for forests contaminated by radiocesium fallout. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 190-191:149-159. [PMID: 29793757 DOI: 10.1016/j.jenvrad.2018.05.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 02/26/2018] [Accepted: 05/07/2018] [Indexed: 06/08/2023]
Abstract
The management of vast forested zones contaminated by radiocesium (rCs) following the Chernobyl and Fukushima fallout is of great social and economic concern in affected areas and requires appropriate dynamic models as predictive or questioning tools. Generally, the existing radio-ecological models need less fragmented data and more ecological realism in their quantitative description of the rCs cycling processes. The model TRIPS ("Transfer of Radionuclide In Perennial vegetation Systems") developed in this study privileged an integrated approach which makes the best use of mass balance studies and available explicit experimental data for Scots pine stands. A main challenge was the differentiation and calibration of foliar absorption as well as root uptake in order to well represent the rCs biocycling. The general dynamics of rCs partitioning was simulated with a relatively good precision against an independent series of observed values. In our scenario the rCs biological cycling enters a steady-state about 15 years after the atmospheric deposits. At that time, the simulations showed an equivalent contribution of foliage and root uptake to the tree contamination. But the root uptake seems not sufficient to compensate the activity decline in the tree. The initial foliar uptake and subsequent internal transfers were confirmed to have a great possible impact on the phasing of tree contamination. An extra finding concerns the roots system acting as a buffer in the early period. The TRIPS model is particularly useful in cases where site-specific integrated datasets are available, but it could also be used with adequate caution to generic sites. This development paves the way for simplification or integration of new modules, as well as for a larger number of other applications for the Chernobyl or Fukushima forests once the appropriate data become available. According to the sensitivity analysis that involves in particular reliable estimates of net foliar uptake as well as root uptake not disconnected from rCs exchange reactions in soil.
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Affiliation(s)
- Yves Thiry
- Andra, Research and Development Division, 1-7 rue Jean-Monnet, 92298 Châtenay-Malabry cedex, France.
| | - Achim Albrecht
- Andra, Research and Development Division, 1-7 rue Jean-Monnet, 92298 Châtenay-Malabry cedex, France
| | - Taku Tanaka
- EDF R&D, LNHE, 6 quai Watier, 78400 Chatou, France
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Nishina K, Hashimoto S, Imamura N, Ohashi S, Komatsu M, Kaneko S, Hayashi S. Calibration of forest 137Cs cycling model "FoRothCs" via approximate Bayesian computation based on 6-year observations from plantation forests in Fukushima. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 193-194:82-90. [PMID: 30218793 DOI: 10.1016/j.jenvrad.2018.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 08/10/2018] [Accepted: 09/04/2018] [Indexed: 06/08/2023]
Abstract
Predicting the environmental fate of 137Cs in forest ecosystems along with the concentrations of 137Cs in tree parts are important for the managements of radioactively contaminated forests. In this study, we calibrate the Forest RothC and Cs model (FoRothCs), a forest ecosystem 137Cs dynamics model, using observational data obtained over six years from four forest sites with different levels of 137Cs contamination from Fukushima Prefecture. To this end, we applied an approximate Bayesian computation (ABC) technique based on the observed 137Cs concentrations (Bq kg-1) of five compartments (leaf, branch, stem, litter, and soil) in a Japanese cedar plantation. The environmental decay (increment) constants of the five compartments were used as the summary statistics (i.e., the metric for model performance) to infer the five parameters related to 137Cs transfer processes in FoRothCs. The ABC technique successfully reconciled the model outputs with the observed trends in 137Cs concentrations at all sites during the study period. Furthermore, the estimated parameters are in agreement with the literature values (e.g., the root uptake rates of 137Cs). Our study demonstrates that model calibration with ABC based on the trends in 137Cs concentrations of multi compartments is useful for reducing the prediction uncertainty of 137Cs dynamics in forest ecosystems.
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Affiliation(s)
- Kazuya Nishina
- Center for Regional Environmental Research, National Institute for Environmental Studies, 305-8506, 16-2, Onogawa, Tsukuba, Ibaraki, Japan.
| | - Shoji Hashimoto
- Forestry and Forest Products Research Institute, 305-8687, 1, Matsunosato, Tsukuba, Ibaraki, Japan; The University of Tokyo, 113-8657, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Naohiro Imamura
- Forestry and Forest Products Research Institute, 305-8687, 1, Matsunosato, Tsukuba, Ibaraki, Japan
| | - Shinta Ohashi
- Forestry and Forest Products Research Institute, 305-8687, 1, Matsunosato, Tsukuba, Ibaraki, Japan
| | - Masabumi Komatsu
- Forestry and Forest Products Research Institute, 305-8687, 1, Matsunosato, Tsukuba, Ibaraki, Japan
| | - Shinji Kaneko
- Kansai Research Center, Forestry and Forest Products Research Institute, 612-0855, 68, Nagaikyutaro, Momoyama, Fushimi, Kyoto, Japan
| | - Seiji Hayashi
- Fukushima Branch, National Institute for Environmental Studies, 963-7700, 10-2, Fukasaku, Miharu, Fukushima, Japan
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17
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Gonze MA, Calmon P. Meta-analysis of radiocesium contamination data in Japanese forest trees over the period 2011-2013. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 601-602:301-316. [PMID: 28570967 DOI: 10.1016/j.scitotenv.2017.05.175] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/15/2017] [Accepted: 05/20/2017] [Indexed: 06/07/2023]
Abstract
The fate and dispersion of radiocesium in forests affected by the Fukushima atmospheric fallouts have been efficiently characterized by Japanese scientists thanks to monitoring surveys of radioactive contents in contaminated soil, water, and vegetation samples at numerous sites. In this paper, we carry out a meta-analysis of the field surveys conducted over the period 2011-2013 in evergreen coniferous and deciduous broadleaf forests of Fukushima or neighboring prefectures. The review focuses on contamination data acquired in tree vegetation - about 1500 spatio-temporal measurements of concentrations, inventories and depuration fluxes - with a particular interest for organs that were directly exposed to the atmospheric fallouts and subjected to depuration mechanisms (foliage, branches and outer bark). To reduce the spatial variability between the sites, radioactive data were normalized by the total deposit estimated at each site. Our analysis highlights the overall consistency of field observations despite the variety of experimental protocols, disparate sampling periods, differences in the forest stand characteristics and variability of the atmospheric deposition conditions. Assuming that the sites conformed to the same dynamics (within the range of residual variability), we then derive, discuss, and compare the mean representative evolutions of radiocesium contamination in the two categories of forest. Thanks to a simple mass balance approach, we finally demonstrate that: (i) about 90% of the radiocesium deposit was intercepted by evergreen coniferous vegetation, (ii) 80% of the deposit was gradually transferred to the forest floor in 3years, according to a well characterized depuration kinetics, and (iii) about 4% was readily absorbed by the foliage and translocated to internal organs (inner bark, stem wood and roots) at a rate of about 10-4d-1.
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Affiliation(s)
- M-A Gonze
- Institute of Radiation Protection and Nuclear Safety, CE Cadarache-Bat 153, BP3 - 13115 St-Paul-lez-Durance Cedex, France.
| | - P Calmon
- Institute of Radiation Protection and Nuclear Safety, CE Cadarache-Bat 153, BP3 - 13115 St-Paul-lez-Durance Cedex, France
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18
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Komatsu M, Hirai K, Nagakura J, Noguchi K. Potassium fertilisation reduces radiocesium uptake by Japanese cypress seedlings grown in a stand contaminated by the Fukushima Daiichi nuclear accident. Sci Rep 2017; 7:15612. [PMID: 29142200 PMCID: PMC5688087 DOI: 10.1038/s41598-017-15401-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/20/2017] [Indexed: 12/03/2022] Open
Abstract
We analysed suppressive effects of potassium (K) fertilisation on radiocesium (137Cs) uptake by hinoki cypress (Chamaecyparis obtusa) seedlings from soils contaminated after the Fukushima Daiichi Nuclear Power Plant accident. Three-year-old seedlings were planted in a clear-cut forest (ca. 4 ha) during June–July 2014, and potassium chloride fertiliser (83 kg K ha−1) was applied twice (August 2014 and April 2015). 137Cs concentrations in the needles in the fertilised plots were one-eighth of those in the control (unfertilised) plots at the end of the second growing season (October 2015). Our results clearly indicated that K fertilisation reduced radiocesium transfer from soil to planted cypress seedlings. A linear mixed model analysis revealed that 137Cs concentrations in the needles were significantly affected by 137Cs inventory in the soil (Bq m−2) adjacent to the sampled seedlings, exchangeable K concentrations in surface mineral soils (0–5 cm) and fertilisation. The exchangeable K concentrations in surface soils in October 2015 did not differ from those in August 2014 (before fertilisation) in the fertilised plots and in the control plots. These results suggested that the levels of exchangeable K would temporarily increase by fertilisation during the growing season, and radiocesium uptake by tree roots was suppressed.
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Affiliation(s)
- Masabumi Komatsu
- Department of Mushroom Science and Forest Microbiology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan.
| | - Keizo Hirai
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Junko Nagakura
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Kyotaro Noguchi
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan.,Tohoku Research Center, Forestry and Forest Products Research Institute, Morioka, Iwate, 020-0123, Japan
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19
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Diener A, Hartmann P, Urso L, Vives I Batlle J, Gonze MA, Calmon P, Steiner M. Approaches to modelling radioactive contaminations in forests - Overview and guidance. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2017; 178-179:203-211. [PMID: 28892730 DOI: 10.1016/j.jenvrad.2017.09.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 09/01/2017] [Accepted: 09/02/2017] [Indexed: 06/07/2023]
Abstract
Modelling the radionuclide cycle in forests is important in case of contamination due to acute or chronic releases to the atmosphere and from underground waste repositories. This article describes the most important aspects to consider in forest model development. It intends to give an overview of the modelling approaches available and to provide guidance on how to address the quantification of radionuclide transport in forests. Furthermore, the most important gaps in modelling the radionuclide cycle in forests are discussed and suggestions are presented to address the variability of forest sites.
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Affiliation(s)
- A Diener
- Bundesamt für Strahlenschutz (BfS), Ingolstaedter Landstr. 1, 85764 Oberschleissheim, Germany.
| | - P Hartmann
- Bundesamt für Strahlenschutz (BfS), Ingolstaedter Landstr. 1, 85764 Oberschleissheim, Germany
| | - L Urso
- Bundesamt für Strahlenschutz (BfS), Ingolstaedter Landstr. 1, 85764 Oberschleissheim, Germany
| | | | - M A Gonze
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), France
| | - P Calmon
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), France
| | - M Steiner
- Bundesamt für Strahlenschutz (BfS), Ingolstaedter Landstr. 1, 85764 Oberschleissheim, Germany
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20
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Imamura N, Komatsu M, Ohashi S, Hashimoto S, Kajimoto T, Kaneko S, Takano T. Temporal changes in the radiocesium distribution in forests over the five years after the Fukushima Daiichi Nuclear Power Plant accident. Sci Rep 2017; 7:8179. [PMID: 28811510 PMCID: PMC5557944 DOI: 10.1038/s41598-017-08261-x] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 07/10/2017] [Indexed: 12/05/2022] Open
Abstract
To elucidate the temporal changes in the radiocesium distribution in forests contaminated by the Fukushima Daiichi Nuclear Power Plant accident, we monitored the 137Cs concentration and inventory within forests from 2011 to 2015 across nine plots containing variable tree species and different contamination levels. The 137Cs concentrations in needles and branches decreased exponentially at all coniferous plots, with effective ecological half-lives of 0.45–1.55 yr for needles and 0.83–1.69 yr for branches. By contrast, the 137Cs concentration in deciduous konara oak leaves did not change over the five years. The concentration of 137Cs in oak wood increased by 37–75%, whereas that in Japanese red pine decreased by 63% over the five years. In Japanese cedar and hinoki cypress, the 137Cs concentration in wood showed an increasing trend in half of the plots. The changes in 137Cs in the organic and mineral soil layers were not strongly related to the tree species or contamination level. Our multi-site, multi-species monitoring results revealed that the pattern of temporal changes in radiocesium in the 9 forest plots was similar overall; however, changes in 137Cs in needles/leaves and wood differed among tree species.
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Affiliation(s)
- Naohiro Imamura
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan.
| | - Masabumi Komatsu
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan. .,Department of Mushroom Science and Forest Microbiology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan.
| | - Shinta Ohashi
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan. .,Department of Wood Properties and Processing, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan.
| | - Shoji Hashimoto
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Takuya Kajimoto
- Tohoku Research Center, Forestry and Forest Products Research Institute, Morioka, Iwate, 020-0123, Japan
| | - Shinji Kaneko
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Tsutomu Takano
- Research Planning and Coordination Department, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
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21
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Radiocaesium partitioning in Japanese cedar forests following the "early" phase of Fukushima fallout redistribution. Sci Rep 2016; 6:37618. [PMID: 27876870 PMCID: PMC5120304 DOI: 10.1038/srep37618] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 10/21/2016] [Indexed: 11/09/2022] Open
Abstract
Our study focused on radiocaesium (137Cs) partitioning in forests, three vegetation periods after the Fukushima Daiichi nuclear power plant accident. 137Cs distribution in forest components (organic and mineral soil layers as well as tree compartments: stem, bark, needles, branches and roots) was measured for two Japanese cedar stand ages (17 and 33 years old). The results showed that around 85% of the initial deposit was found in the forest floor and topsoil. For the youngest stand almost 70% of the deposit is present in the forest floor, whereas for the oldest stand 50% is present in the 0-3 cm mineral soil layer. For trees, old and perennial organs (including dead and living needles and branches, litter fall and outer bark) directly exposed to the fallout remained the most contaminated. The crown concentrated 61-69% of the total tree contamination. Surprisingly the dead organs concentrated 25 ± 9% (young cedars) to 36 ± 20% (mature cedar) of the trees' residual activity, highlighting the importance of that specific compartment in the early post-accident phase for Japanese cedar forests. Although the stem (including bark) represents the highest biomass pool, it only concentrates 3.3% and 4.6% of the initial 137Cs deposit for mature and young cedars, respectively.
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Yoshihara T, Matsumura H, Hashida SN, Nakaya K. Radiocesium contamination in living and dead foliar parts of Japanese cedar during 2011-2015. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 164:291-299. [PMID: 27537824 DOI: 10.1016/j.jenvrad.2016.08.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 07/27/2016] [Accepted: 08/07/2016] [Indexed: 06/06/2023]
Abstract
Radiocesium (137Cs) activity concentrations, mainly derived from the Fukushima accident of March 2011, were measured in green foliar parts without separation by age (bulk green foliar parts; GL) and litterfall (LF) of Japanese cedar (Cryptomeria japonica) from 2011 to 2015. In all samples, 137Cs concentrations decreased exponentially over time, but were always higher in LF (7.36-0.58 Bq g-DW-1) than in GL (2.10-0.06 Bq g-DW-1). The difference in the decreasing rate between GL and LF would reflect a difference in the dominant factor of the decrease between living and dead tissues (i.e., internal translocation and weathering, respectively). Over this same timeframe, potassium (K) concentrations in both GL and LF experienced repetitive periodical changes within a certain range (0.38-3.0 mg g-DW-1 for LF and 2.08-4.77 mg g-DW-1 for GL, respectively). Thus, there was no specific correlation between 137Cs and K concentrations in LF and GL. However, analyses of the age classified green foliar parts (GL-S) and dead foliar parts still retained on trees (DL) could indicate another view. The annual changes in residual rates of both 137Cs and K concentrations in GL-S demonstrated very similar two-phase reductions (i.e., a faster reduction in each expansion year than in the following years) and an obvious linear correlation between each other. Radiocesium concentration in DL were always higher than in any part of GL-S sampled at the same timing, but K concentrations showed the reverse relation. It is probable that 137Cs is basically translocated from older parts to the developing parts (as long as the former are alive) via a seasonal nutritional flow of K; however, a part of 137Cs translocation would cease considerably earlier than the cessation of K translocation.
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Affiliation(s)
- Toshihiro Yoshihara
- Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194, Japan.
| | - Hideyuki Matsumura
- Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194, Japan
| | - Shin-Nosuke Hashida
- Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194, Japan
| | - Ko Nakaya
- Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194, Japan
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