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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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Montgomery DA, Edayilam N, Page H, Sheriff SA, Tharayil N, Powell BA, Martinez NE. Comparative uptake, translocation, and plant mediated transport of Tc-99, Cs-133, Np-237, and U-238 in Savannah River Site soil columns for the grass species Andropogon virginicus. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 857:159400. [PMID: 36243070 DOI: 10.1016/j.scitotenv.2022.159400] [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: 08/01/2022] [Revised: 10/08/2022] [Accepted: 10/08/2022] [Indexed: 06/16/2023]
Abstract
This study examines the ability of the grass species Andropogon virginicus to alter the subsurface transport and redistribution of a suite of radionuclides (99Tc, 133Cs (stable analog for 135Cs and 137Cs), 237Np, 238U) with varying chemical behaviors in a Savannah River Site soil via the use of vegetated and unvegetated soil columns. After an acclimation period, a small volume of solution containing all radionuclides was introduced into the columns via Rhizon© pore water sampling tubes. Plants were grown for an additional 4 weeks before shoots were harvested, and columns were prepared for sampling. Plant presence led to decreased radionuclide release from the columns, mainly due to radionuclide specific combinations of system hydrology differences resulting from plant transpiration as well as plant uptake. For the most mobile radionuclides, 99Tc followed by 237Np, plant presence resulted in significantly different soil concentration profiles between vegetated and unvegetated columns, including notable upward migration for 237Np in columns with plants. Additionally, plant uptake of 99Tc was the greatest of all the radionuclides, with plant tissues containing an average of 44 % of the 99Tc, while plant uptake only accounted for <2 % of 237Np and <0.5 % of 133Cs and 238U in the system. Although overall plant uptake of 133Cs and 238U were similar, the majority of 133Cs taken up by plants was associated with 133Cs already available in the aqueous phase while 238U uptake was mainly associated with the solid phase, meaning that plant activity resulted in a fraction of the native 238U being mobilized and thus, made available for plant uptake. Overall, this study quantified the influence of several plant-mediated physical and biogeochemical factors that have significant influence on radionuclide mobility and transport in this complex system which can be further utilized in future system or site-specific environmental transport and risk assessment models.
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Affiliation(s)
- Dawn A Montgomery
- Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC, USA; Center for Nuclear Environmental Engineering Sciences and Radioactive Waste Management (NEESRWM), Clemson University, Clemson, SC, USA.
| | - Nimisha Edayilam
- Department of Plant and Environmental Science, Clemson University, Clemson, SC, USA
| | - Hayden Page
- Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC, USA
| | - S Andrew Sheriff
- Department of Chemical and Biomolecular Engineering, Clemson University, Clemson, SC, USA
| | - Nishanth Tharayil
- Department of Plant and Environmental Science, Clemson University, Clemson, SC, USA
| | - Brian A Powell
- Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC, USA; Center for Nuclear Environmental Engineering Sciences and Radioactive Waste Management (NEESRWM), Clemson University, Clemson, SC, USA
| | - Nicole E Martinez
- Department of Environmental Engineering and Earth Sciences, Clemson University, Clemson, SC, USA; Center for Nuclear Environmental Engineering Sciences and Radioactive Waste Management (NEESRWM), Clemson University, Clemson, SC, USA
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Yoschenko V, Nanba K, Wada T, Johnson TE, Zhang J, Workman D, Nagata H. Late phase radiocesium dynamics in Fukushima forests post deposition. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2022; 251-252:106947. [PMID: 35732077 DOI: 10.1016/j.jenvrad.2022.106947] [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: 02/13/2022] [Revised: 06/14/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
The long term dynamics of radiocesium in typical forest ecosystems was studied in the radioactive contaminated areas in Fukushima Prefecture. Six observations sites located in Yamakiya Village (Kawamata Town; since 2014), Tsushima Village (Namie Town, since 2015), and Tomioka Town (since 2017) were monitored. The forests consisted of artificial plantations of Japanese cedar (Cryptomeria japonica) at Yamakiya Village, Tsushima Village, and Tomioka Town. Tsushima Village also had a natural mixed forest dominated by Japanese red pine (Pinus densiflora), and Tomioka Town had a young and a mature artificial plantation of Japanese cypress (Chamaecyparis obtuse). Concentrations of 137Cs were monitored in the samples collected from the main aboveground biomass compartments, fresh litterfall, forest litter, and soil. Concentrations of exchangeable forms of 137Cs and stable K were measured in soil samples. During the observation period, the litter radiocesium inventories at all sites decreased significantly to approximately 1% or less of the total ground deposition. Approximately 80% of the total radiocesium inventory is localized in the upper 5-cm layer of soil and there is little downward migration of radiocesium. At the sites with the longest monitoring series (Yamakiya and Tsushima), the radiocesium expectation depths and expectation mass depths were relatively constant at 2-3 cm and 5-6 kg m-2, respectively. Aboveground biomass compartments showed similar decreasing trends in radiocesium aggregated transfer factors, Tag, in the compartments that were exposed to atmospheric fallout in March 2011 (old foliage, small branches, and outer bark). The mean Tag in cedar stand compartments currently are in the range of 10-3-10-2 m2 kg-1 dw. However, the mean Tag and their dynamic trend significantly differed in the wood compartments of the cedar stands, which may indicate root uptake differences of orders of magnitude between observation sites. The difference in radiocesium concentration in wood between the sites becomes less pronounced when normalized by the ratio of exchangeable 137Cs/K in the soils.
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Affiliation(s)
- Vasyl Yoschenko
- Institute of Environmental Radioactivity at Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan.
| | - Kenji Nanba
- Institute of Environmental Radioactivity at Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
| | - Toshihiro Wada
- Institute of Environmental Radioactivity at Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
| | - Thomas E Johnson
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, 80523, United States
| | - Jian Zhang
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, 80523, United States
| | - Daniel Workman
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, 80523, United States
| | - Hiroko Nagata
- Institute of Environmental Radioactivity at Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, 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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Atarashi-Andoh M, Koarashi J, Tsuduki K, Takeuchi E, Nishimura S, Muto K, Matsunaga T. Spatial variations in radiocesium deposition and litter-soil distribution in a mountainous forest catchment affected by the Fukushima nuclear accident. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2021; 238-239:106725. [PMID: 34461367 DOI: 10.1016/j.jenvrad.2021.106725] [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: 03/08/2021] [Revised: 08/19/2021] [Accepted: 08/23/2021] [Indexed: 06/13/2023]
Abstract
The Fukushima Dai-ichi Nuclear Power Plant accident caused serious 137Cs contamination in mountainous forest areas. To understand the spatial variation in soil 137Cs inventory in complex mountainous topography and the influencing factors, a whole-area investigation of 137Cs deposition in a broad-leaved forest catchment of a mountain stream was conducted using grid sampling. Across the catchment, organic and surface mineral soil layers were collected at 42 locations in 2013 and 6 locations in 2015. Cesium-137 deposition on the forest floor exhibited high spatial heterogeneity and altitude-dependent distribution over the catchment. The 137Cs retention ratio in the organic layer, determined as the inventory in the organic layer divided by the soil (organic and mineral soil layers) inventory, ranged from 6% to 82% in 2013, and the coefficient of variation was 0.6. The 137Cs retention ratios had positive correlations with the material inventory in the organic layer and the elevation. The 137Cs retention ratios in the organic layer were less than 20% in 2015, even at the locations where the retention ratio was higher than 55% in 2013. Although there was spatial variation in the migration speed, 137Cs migration from the organic layer to mineral soil was almost completed within 4 y of the deposition, suggesting a decrease in 137Cs circulation within the forest ecosystem. This study also examined a relationship between the 137Cs inventory and the air dose rate to assess the potential of using the air dose rate to estimate soil 137Cs inventory. Soil 137Cs inventories and air dose rates were highly positively correlated, indicating that measurement of air dose rate can provide an easier and quicker alternative to measurement of soil 137Cs inventory in forest ecosystems.
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Affiliation(s)
- Mariko Atarashi-Andoh
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan.
| | - Jun Koarashi
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Katsunori Tsuduki
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Erina Takeuchi
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Syusaku Nishimura
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Kotomi Muto
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Takeshi Matsunaga
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
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Nguyen Phuong T, Kaneko S, Koya S, Ohira H, Tsukada H. Radiation dose rate to Japanese cedar and plants collected from Okuma, Fukushima Prefecture. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 779:146350. [PMID: 33744576 DOI: 10.1016/j.scitotenv.2021.146350] [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: 01/04/2021] [Revised: 03/01/2021] [Accepted: 03/03/2021] [Indexed: 06/12/2023]
Abstract
After the 2011 Fukushima Dai-ichi Nuclear Power Station (FDNPS) accident, wild populations of animals and plants living in the evacuation zone received additional ionizing radiation of both internal and external radiation doses. Morphological abnormalities of pine and fir trees near the FDNPS were reported. In order to evaluate dose-effect relationships, it is necessary to quantify the radiation doses to trees and plants. In this study, the internal and external dose rates to Japanese cedar and plants collected at three sites in Okuma, approximately 4 km southwest of FDNPS were estimated applying the ERICA Assessment Tool. The activity concentrations of 134Cs and 137Cs in soils, cedar trunks, and plants were determined. The total dose rates to cedar ranged from 2.2 ± 1.2 to 6.1 ± 2.2 μGy h-1. These rates were within the derived consideration reference levels (DCRLs) reported by ICRP 108 as 4-40 μGy h-1 for pine trees. The highest estimate for plants was 7.1 ± 2.7 μGy h-1, much smaller than the DCRLs reported for grasses and herbs (40-400 μGy h-1). On average, the internal radiation dose rates to cedars at the two sites accounted for 5% and 29% of the external dose rates, respectively, while the value in another site was only 0.4% for cedar. This was attributed to differences in the crown area between the three sites. The trunk diameter of cedars shows a positive correlation with the ratio of internal to external radiation dose rates. It indicates that the total dose rate to cedars is easily estimated with the soil radiocaesium inventory and trunk diameter. The internal radiation dose rate to the plant varied depending on the plant species. This variation was considerably large in plants due to the presence of two species, including Solidago altissima and Artemisia indica var. maximowiczii.
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Affiliation(s)
- Thoa Nguyen Phuong
- Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima Prefecture 960-1296, Japan; Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima Prefecture 960-1296, Japan
| | - Shingo Kaneko
- Faculty of Symbiotic Systems Science, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima Prefecture 960-1296, Japan; Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima Prefecture 960-1296, Japan
| | - Shishido Koya
- Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima Prefecture 960-1296, Japan
| | - Hajime Ohira
- Graduate School of Symbiotic Systems Science and Technology, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima Prefecture 960-1296, Japan
| | - Hirofumi Tsukada
- Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima City, Fukushima Prefecture 960-1296, Japan.
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Vanhoudt N, Van Gompel A, Vives I Batlle J. Distribution and behaviour of naturally occurring radionuclides within a Scots pine forest grown on a CaF 2 waste deposit related to the Belgian phosphate industry. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2021; 233:106591. [PMID: 33798812 DOI: 10.1016/j.jenvrad.2021.106591] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 03/10/2021] [Accepted: 03/11/2021] [Indexed: 06/12/2023]
Abstract
The distribution and behaviour of naturally occurring radionuclides within a vegetated part of a CaF2 sludge heap from the Belgian phosphate industry was studied. A Scots pine forest plot was selected as study area. Trees were approximately 20 years old and showed a disturbed health state. Seasonal sampling campaigns of soil, roots, wood, inner and outer bark, needles and twigs gave insight on 238U, 226Ra, 210Pb and 210Po transfer and distribution between pine tree compartments. Soil samples were analysed for their texture, total organic and inorganic carbon, field capacity, pH and radionuclide content. Solid-liquid distribution coefficients (Kd) were experimentally determined for 238U, 226Ra (using Ba as analogue) and 210Pb based on adsorption-desorption batch tests. Results indicated higher 238U, 232Th, 226Ra, 210Pb and 210Po activity concentrations in the deeper soil layers while the first 20 cm contained less radionuclides but had a higher level of organic carbon. Additionally, results indicated no seasonal changes in the 238U:226Ra ratio in the soil while the 226Ra:210Pb ratio was significantly higher in spring compared to winter in the 20-60 cm soil layer. Pine tree roots served as natural translocation barrier for all radionuclides with high retention in the roots and low translocation to the above ground tree compartments. When considering the above ground compartments, 210Pb and 210Po were mostly present in the bark, needles and twigs. Furthermore, 238U and its progeny were highly accumulated in mosses. These results allowed us to establish more realistic soil-to-plant transfer factors. In addition, experimentally mimicking pore water acidification in the root zone resulted in lower 238U and 210Pb Kd values compared to using a standard CaCl2 solution. This study provides an integrated radioecological picture of knowledge and site specific data needed to study the long-term influence of vegetation on radionuclide dispersion in forest ecosystems.
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Affiliation(s)
- Nathalie Vanhoudt
- Biosphere Impact Studies, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400 Mol, Belgium.
| | - Axel Van Gompel
- Biosphere Impact Studies, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400 Mol, Belgium
| | - Jordi Vives I Batlle
- Biosphere Impact Studies, Belgian Nuclear Research Centre (SCK CEN), Boeretang 200, 2400 Mol, Belgium
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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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Malins A, Imamura N, Niizato T, Takahashi J, Kim M, Sakuma K, Shinomiya Y, Miura S, Machida M. Calculations for ambient dose equivalent rates in nine forests in eastern Japan from 134Cs and 137Cs radioactivity measurements. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2021; 226:106456. [PMID: 33217723 DOI: 10.1016/j.jenvrad.2020.106456] [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: 08/19/2020] [Revised: 10/29/2020] [Accepted: 11/04/2020] [Indexed: 06/11/2023]
Abstract
Understanding the relationship between the distribution of radioactive 134Cs and 137Cs in forests and ambient dose equivalent rates (H˙∗(10)) in the air is important for researching forests in eastern Japan affected by the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. This study used a large number of measurements from forest samples, including 134Cs and 137Cs radioactivity concentrations, densities and moisture contents, to perform Monte Carlo radiation transport simulations for H˙∗(10) between 2011 and 2017. Calculated H˙∗(10) at 0.1 and 1 m above the ground had mean residual errors of 19% and 16%, respectively, from measurements taken with handheld NaI(Tl) scintillator survey meters. Setting aside the contributions from natural background radiation, 134Cs and 137Cs in the organic layer and the top 5 cm of forest soil generally made the largest contributions to calculated H˙∗(10). The contributions from 134Cs and 137Cs in the forest canopy were calculated to be largest in the first two years following the accident. Uncertainties were evaluated in the simulation results due to the measurement uncertainties in the model inputs by assuming Gaussian measurement errors. The mean uncertainty (relative standard deviation) of the simulated H˙∗(10) at 1 m height was 11%. The main contributors to the total uncertainty in the simulation results were the accuracies to which the 134Cs and 137Cs radioactivities of the organic layer and top 5 cm of soil, and the vertical distribution of 134Cs and 137Cs within the 5 cm soil layers, were known. Radioactive cesium located in the top 5 cm of soil was the main contributor to H˙∗(10) at 1 m by 2016 or 2017 in the calculation results for all sites. Studies on the 137Cs distribution within forest soil will therefore help explain radiation levels henceforth in forests affected by the FDNPP accident. The merits of this study are that it modelled multiple forests for a long time period, with the important model inputs being informed by field measurements, and it quantified how the measurement uncertainties in these inputs affected the calculation results.
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Affiliation(s)
- Alex Malins
- Japan Atomic Energy Agency, Center for Computational Science and e-Systems, 178-4-4 Wakashiba, Kashiwa, Chiba, 277-0871, Japan.
| | - Naohiro Imamura
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Tadafumi Niizato
- Japan Atomic Energy Agency, Collaborative Laboratories for Advanced Decommissioning Science (CLADS) Environmental Research Group, 10-2 Fukasaku, Miharu-machi, Tamura-gun, Fukushima, 963-7700, Japan
| | - Junko Takahashi
- Center for Research in Isotopes and Environmental Dynamic, University of Tsukuba, Tennodai 1-1-1, Tsukuba-shi, Ibaraki, 305-8572, Japan
| | - Minsik Kim
- Japan Atomic Energy Agency, Center for Computational Science and e-Systems, 178-4-4 Wakashiba, Kashiwa, Chiba, 277-0871, Japan
| | - Kazuyuki Sakuma
- Japan Atomic Energy Agency, Collaborative Laboratories for Advanced Decommissioning Science (CLADS) Environmental Research Group, 10-2 Fukasaku, Miharu-machi, Tamura-gun, Fukushima, 963-7700, Japan
| | - Yoshiki Shinomiya
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Satoru Miura
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Masahiko Machida
- Japan Atomic Energy Agency, Center for Computational Science and e-Systems, 178-4-4 Wakashiba, Kashiwa, Chiba, 277-0871, Japan
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10
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Gonze MA, Calmon P, Hurtevent P, Coppin F. Meta-analysis of radiocesium contamination data in Japanese cedar and cypress forests over the period 2011-2017. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 750:142311. [PMID: 33182179 DOI: 10.1016/j.scitotenv.2020.142311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/07/2020] [Accepted: 09/07/2020] [Indexed: 06/11/2023]
Abstract
Since Fukushima accident, dozens of field studies have been conducted in order to quantify and understand the behaviour of atmospheric radiocesium (137Cs) fallouts in contaminated forests of Fukushima and neighbouring prefectures. In this paper, we carry out a detailed review of data acquired over 2011-2017 in Japanese cedar and cypress plantations, focusing on aerial tree organs, soil layers and tree-to-soil depuration fluxes. To enable comparison and reinforce the consistency between sites, radiological measurements were normalized by the deposit and interpolated onto the same spatio-temporal frame. Despite some (poorly explained) residual variability, we derived a "mean" pattern by log-averaging data among sites. These "mean" results were analysed with the help of a simple mass-balance approach and discussed in the light of post-Fukushima literature. We demonstrated that the activity levels and dynamics in all compartments were consistent and generally well reproduced by the mass balance approach, for values of the interception fraction between 0.7 and 0.85. The analysis indicated that about 5% of the initial deposit remained in the aerial vegetation after 6 years, more than two thirds of intercepted 137Cs being transferred to the soil due to throughfall. The simulations indicated that foliar uptake might have contributed between 40% and 100% to the activity transferred to stem wood. The activity concentration in canopy organs rapidly decreased in the first few months then more slowly, according to an effective half-life of about 1.6 years. The activity level in the organic layer peaked in summer 2011 then decreased according to an effective half-life of 2.2 years. After a rapid increase in 2011, the contamination of mineral horizons continued to increase more slowly, 85% of 137Cs incoming through the organic layer being retained in the 0-5 cm layer according to a mean residence time longer than in the upper layer (7 against 1.5 years).
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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
| | - P Hurtevent
- Institute of Radiation Protection and Nuclear Safety, CE Cadarache-Bat 153, BP3, 13115 St-Paul-lez-Durance cedex, France
| | - F Coppin
- Institute of Radiation Protection and Nuclear Safety, CE Cadarache-Bat 153, BP3, 13115 St-Paul-lez-Durance cedex, France
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11
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Nemoto Y, Oomachi H, Saito R, Kumada R, Sasaki M, Takatsuki S. Effects of 137Cs contamination after the TEPCO Fukushima Dai-ichi Nuclear Power Station accident on food and habitat of wild boar in Fukushima Prefecture. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 225:106342. [PMID: 32949874 DOI: 10.1016/j.jenvrad.2020.106342] [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: 11/29/2019] [Revised: 06/02/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
After the Tokyo Electric Power Company Fukushima Dai-ichi Nuclear Power Station accident, wild boar was found to have greater radiocesium (137Cs) activity concentrations in their bodies than other wild animals in Japan; however, the reason for this remains unknown. To understand the mechanism of 137Cs transfer from the environment to wild boar, and the factors that affect variation in 137Cs contamination in wild boar, we sampled muscle and stomach contents from wild boar captured in Fukushima Prefecture and analyzed the relationships among 137Cs concentrations in muscle tissue and in the stomach contents, 137Cs ground deposition at capture sites, and wild boar food habits. Significant positive relationships were observed among 137Cs activity concentrations in muscle and stomach contents, as well as 137Cs deposition density at capture sites. These results suggest that 137Cs is transferred from the environment to plant and animal materials consumed by wild boar, and then from these foods to the bodies of wild boar through digestion. However, no correlation was observed between 137Cs concentrations in stomach contents and the presence of any particular food item in stomachs of wild boar, including mushrooms. These findings suggest mushrooms and underground food items, which were found to affect 137Cs concentrations in wild animals in Europe, were not important contributors to high levels of 137Cs contamination in Japanese wild animals.
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Affiliation(s)
- Yui Nemoto
- Fukushima Prefectural Centre for Environmental Creation, 10-2, Fukasaku, Miharu Town, Fukushima, 963-7700, Japan; Tokyo University of Agriculture, 1-1-1, Sakuragaoka, Setagaya-ku, Tokyo, 156-8502, Japan.
| | - Hitoshi Oomachi
- Fukushima Prefectural Centre for Environmental Creation, 10-2, Fukasaku, Miharu Town, Fukushima, 963-7700, Japan; Fukushima Prefecture, 2-16, Sugitsumatyou, Fukushima, Fukushima, 960-8670, Japan
| | - Rie Saito
- Fukushima Prefectural Centre for Environmental Creation, 10-2, Fukasaku, Miharu Town, Fukushima, 963-7700, Japan
| | - Reiko Kumada
- Fukushima Prefectural Centre for Environmental Creation, 10-2, Fukasaku, Miharu Town, Fukushima, 963-7700, Japan
| | - Masataka Sasaki
- Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan
| | - Seiki Takatsuki
- The Life Museum of Azabu University, 1-17-71, Fuchinobe, Chuo-ku, Sagamihara, Kanagawa, 252-5201, Japan
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12
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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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13
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Holiaka D, Yoschenko V, Levchuk S, Kashparov V. Distributions of 137Cs and 90Sr activity concentrations in trunk of Scots pine (Pinus sylvestris L.) in the Chernobyl zone. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 222:106319. [PMID: 32565416 DOI: 10.1016/j.jenvrad.2020.106319] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 05/25/2020] [Accepted: 05/25/2020] [Indexed: 06/11/2023]
Abstract
Possibility of the economical utilization of forests in the radioactive contaminated areas depends on compliance of the radionuclide activity concentrations in wood with the hygiene norms or national standards that are established by the governments or regulators. Since such regulations consider wood as a whole, development of the sampling methods for assessment of compliance of wood to the norms or standards requires the adequate addressing the issues related to heterogeneity of the radionuclide distributions within the tree trunks. In this paper we present spatial distributions of the 90Sr and 137Cs activity concentrations in the trunk wood of mature Scots pine (Pinus sylvestris L.) trees in the Chernobyl exclusion zone in the late stage (30 years) after the deposition. Four 52-53 year old model trees were sampled in the forest stand located in approximately 5 km from the accidental nuclear reactor. The radionuclide concentrations were measured in 156 wood samples collected from the wood disks cut off the tree trunks at the set of heights. To address variability of the tree sizes and radionuclide concentrations between the individual trees, we applied the corresponding relative indices enabling identification of the general patterns of the spatial distributions of 90Sr and 137Cs. We demonstrated significant differences in bioavailability and distribution trends between the studied radionuclides. 137Cs is translocated to the younger parts of the tree trunk, while the 90Sr concentrations are higher in heartwood and in senescing tissues, which is explained by the different chemical properties of Cs and Sr and by different physiological roles played in plant development by their chemical analogs and major plant nutrition elements, Ca and K respectively. In this reason, the principal distribution patterns of the studied radionuclides in the trunk wood do not significantly change with time, and the results of our study generally are in good agreement with those obtained in the earlier stage after the deposition. The above trends are clearly expressed in both radial and longitudinal directions and result in systematic deviation of the concentrations estimated based on core sampling from the average concentrations in the whole tree trunk.
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Affiliation(s)
- Dmytrii Holiaka
- Ukrainian Institute of Agricultural Radiology of the National University of Life and Environmental Sciences of Ukraine, Mashinobudivnykiv str. 7, Chabany, Kyiv region, 08162, Ukraine.
| | - Vasyl Yoschenko
- Institute of Environmental Radioactivity at Fukushima University, 1 Kanayagawa, Fukushima, Fukushima, Prefecture, 960-1296, Japan
| | - Sviatoslav Levchuk
- Ukrainian Institute of Agricultural Radiology of the National University of Life and Environmental Sciences of Ukraine, Mashinobudivnykiv str. 7, Chabany, Kyiv region, 08162, Ukraine
| | - Valery Kashparov
- Ukrainian Institute of Agricultural Radiology of the National University of Life and Environmental Sciences of Ukraine, Mashinobudivnykiv str. 7, Chabany, Kyiv region, 08162, Ukraine
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14
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Koarashi J, Atarashi-Andoh M, Nishimura S, Muto K. Effectiveness of decontamination by litter removal in Japanese forest ecosystems affected by the Fukushima nuclear accident. Sci Rep 2020; 10:6614. [PMID: 32313049 PMCID: PMC7171154 DOI: 10.1038/s41598-020-63520-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 03/31/2020] [Indexed: 11/09/2022] Open
Abstract
The Fukushima Daiichi nuclear power plant accident caused serious radiocesium (137Cs) contamination of forest ecosystems over a wide area. The removal of the forest floor litter layer has been considered a potential method for forest decontamination; however, its effectiveness remains largely unknown. We conducted a pilot-scale decontamination study in a deciduous broadleaved forest in Fukushima. The entire forest was decontaminated by removing the litter layer in July 2014, approximately 3.3 years after the accident, with the exception of two untreated plots. For three years after decontamination, we quantified 137Cs contamination levels in the litter and topsoil layers and in the tree leaves, in the untreated and decontaminated areas. The decreased inventories of litter materials and the litter-associated 137Cs in the decontaminated areas were observed only in the first year after decontamination. Generally, no decontamination effects were observed on the 137Cs transfer in tree leaves. The primary reason for this was the rapid shift in the main reservoir of 137Cs from litter layers to the underlying mineral soil, which differs from the observations in post-Chernobyl studies of European forest ecosystems. The results suggest that litter-removal decontamination can only be successful if it is implemented more quickly (within 1-2 years after the accident) for Japanese forest ecosystems.
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Affiliation(s)
- Jun Koarashi
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan.
| | - Mariko Atarashi-Andoh
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Syusaku Nishimura
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Kotomi Muto
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
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15
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Teramage MT, Onda Y, Kato H, Sun X. Impact of forest thinning on the dynamics of litterfall derived 137Cs deposits in coniferous forest floor after Fukushima accident. CHEMOSPHERE 2020; 239:124777. [PMID: 31518924 DOI: 10.1016/j.chemosphere.2019.124777] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Revised: 07/27/2019] [Accepted: 09/04/2019] [Indexed: 06/10/2023]
Abstract
The effects of a 50% forest thinning intensity on Fukushima-derived 137Cs deposition by litterfall and its discharge by runoff in hillslope coniferous forest were monitored using four litterfall traps and a hillslope erosion plot. The observation was underway during the pre-and post-thinning periods. Results demonstrated that during the pre-thinning period a total 150 ± 13 g m-2 of litterfall deposited about 924 ± 69 Bq m-2 of 137Cs. This accounts for 11% of the local 137Cs fallout recorded for the study site in the aftermath of the accident. After thinning, both litterfall and 137Cs increased by more than six- and two-fold, respectively. This is possibly owing to the slow individual tree recovery rate assisted by the change on the running space provided by canopy openings, which can accelerate even the normal gust wind to gain damaging power on the unshielded mechanically injured parts of the contaminated residual trees. In both cases, litterfall generally transferred about 37% (3 ± 0.2 kBq m-2) of the local 137Cs fallout onto the forest floor over the observation period. The eroded litter-associated 137Cs increased by about a factor of two after thinning, which only accounted for less than 1% of 137Cs deposited by litterfall. This implies that the forest floor retains 137Cs and remains contaminated regardless of the size of the eroded litter material. But this could become a potential secondary contamination source for the downstream resources such as water bodies and villages, especially at the time of flooding, which in turn calls a serious attention in designing decontamination schemes.
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Affiliation(s)
- Mengistu T Teramage
- Institute of Radiological and Nuclear Safety (IRSN), 13115, Cadarche, France; School of Plant and Horticultural Sciences, College of Agriculture, Hawassa University, Ethiopia.
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 305-8572, Japan
| | - Hiroaki Kato
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 305-8572, Japan
| | - Xinchao Sun
- Institute of Surface -Earth System Science, Tianjin University, 30-0072, China.
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16
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Teramage MT. Temporal distribution of Fukushima-derived 137Cs in coniferous forest soil evaluated based on compartment-exponential model. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:36913-36921. [PMID: 31741278 DOI: 10.1007/s11356-019-06803-6] [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: 04/29/2019] [Accepted: 10/16/2019] [Indexed: 06/10/2023]
Abstract
Based on the compartment and exponential models, the distribution of Fukushima-derived 137Cs was evaluated at four sampling dates in undisturbed coniferous forest soil. The compartment model was employed to evaluate the dynamic of 137Cs in the three sub-sections of the forest floor (FF), namely undergrowth (UG), litter layer (OL), and fragmented litter layer (OF), while the exponential model was administrated to describe its distribution below the FF. According to the compartment model, the derived ecological half-life of 137Cs in the UG, OL, and OF layers was 0.97, 1.1, and 4.9 years, respectively, indicating 137Cs resides much longer in the OF layer. Hence, this soil section remains a potential source of radiation dose mainly due to its high 137Cs content associated with low attenuation effect. Below the OF layer, the 137Cs distribution was well described by exponential model and its derived relaxation lengths were in the range of 0.8-1.4 cm, implying the migration of 137Cs in mineral soil is very slow and almost intact during the observation time. Collectively, our results highlighted that the compartment model for the FF and the exponential model for the soil below the FF are adequate enough to generate essential information. Thus, the potential decontamination measures should have to be chosen on their effect on the FF's 137Cs. Graphical abstract.
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Affiliation(s)
- Mengistu T Teramage
- Hawassa University, College of Agriculture, P.O. Box 676, Hawassa, Ethiopia.
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17
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Sakuma K, Tsuji H, Hayashi S, Funaki H, Malins A, Yoshimura K, Kurikami H, Kitamura A, Iijima K, Hosomi M. Applicability of K d for modelling dissolved 137Cs concentrations in Fukushima river water: Case study of the upstream Ota River. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 210:105815. [PMID: 30340874 DOI: 10.1016/j.jenvrad.2018.09.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 12/25/2017] [Accepted: 01/04/2018] [Indexed: 06/08/2023]
Abstract
A study is presented on the applicability of the distribution coefficient (Kd) absorption/desorption model to simulate dissolved 137Cs concentrations in Fukushima river water. The upstream Ota River basin was simulated using GEneral-purpose Terrestrial Fluid-flow Simulator (GETFLOWS) for the period 1 January 2014 to 31 December 2015. Good agreement was obtained between the simulations and observations on water and suspended sediment fluxes, and on particulate bound 137Cs concentrations under both base and high flow conditions. By contrast the measured concentrations of dissolved 137Cs in the river water were much harder to reproduce with the simulations. By tuning the Kd values for large particles, it was possible to reproduce the mean dissolved 137Cs concentrations during base flow periods (observation: 0.32 Bq/L, simulation: 0.36 Bq/L). However neither the seasonal variability in the base flow dissolved 137Cs concentrations (0.14-0.53 Bq/L), nor the peaks in concentration that occurred during storms (0.18-0.88 Bq/L, mean: 0.55 Bq/L), could be reproduced with realistic simulation parameters. These discrepancies may be explained by microbial action and leaching from organic matter in forest litter providing an additional input of dissolved 137Cs to rivers, particularly over summer, and limitations of the Kd absorption/desorption model. It is recommended that future studies investigate these issues in order to improve simulations of dissolved 137Cs concentrations in Fukushima rivers.
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Affiliation(s)
- Kazuyuki Sakuma
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588, Japan.
| | - Hideki Tsuji
- Fukushima Branch, National Institute of Environmental Studies, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Seiji Hayashi
- Fukushima Branch, National Institute of Environmental Studies, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Hironori Funaki
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Alex Malins
- Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Kazuya Yoshimura
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Hiroshi Kurikami
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Akihiro Kitamura
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Kazuki Iijima
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Masaaki Hosomi
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588, Japan
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18
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Muto K, Atarashi-Andoh M, Matsunaga T, Koarashi J. Characterizing vertical migration of 137Cs in organic layer and mineral soil in Japanese forests: Four-year observation and model analysis. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 208-209:106040. [PMID: 31518883 DOI: 10.1016/j.jenvrad.2019.106040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/20/2019] [Accepted: 08/27/2019] [Indexed: 06/10/2023]
Abstract
Because of the Fukushima Dai-ichi Nuclear Power Plant accident, forest ecosystems in wide areas were contaminated with 137Cs. It is important to characterize the behavior of 137Cs after its deposition onto forest surface environments for evaluating and preventing long-term radiation risks. In the present study, 137Cs vertical distributions in the soil profile were observed repeatedly at five forest sites with different vegetation types for 4.4 years after the accident in 2011, and 137Cs migration in the organic layer and mineral soil was analyzed based on a comparison of models and observations. Cesium-137 migration from the organic layer to the underlying mineral soil was represented by a two-component exponential model. Cesium-137 migration from the organic layer was faster than that observed in European forests, suggesting that the mobility and bioavailability of 137Cs could be suppressed rapidly in Japanese forests. At all sites, 137Cs transfer in mineral soil could be reproduced by a simple diffusion equation model with continuous 137Cs supply from the organic layer. The diffusion coefficients of 137Cs in the mineral soil were estimated to be 0.042-0.55 cm2 y-1, which were roughly comparable with those of European forest soils affected by the Chernobyl Nuclear Power Plant accident. Model predictions using the determined model parameters indicated that 10 years after the accident, more than 70% of the deposited 137Cs will migrate to the mineral soil but only less than 10% of the total 137Cs inventory will penetrate deeper than 10 cm in the mineral soil across all sites. The results of the present study suggest that the 137Cs deposited onto Japanese forest ecosystems will be retained in the surface layers of mineral soil for a long time.
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Affiliation(s)
- Kotomi Muto
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Mariko Atarashi-Andoh
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Takeshi Matsunaga
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Jun Koarashi
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan.
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19
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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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20
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Koarashi J, Nishimura S, Atarashi-Andoh M, Muto K, Matsunaga T. A new perspective on the 137Cs retention mechanism in surface soils during the early stage after the Fukushima nuclear accident. Sci Rep 2019; 9:7034. [PMID: 31065040 PMCID: PMC6504853 DOI: 10.1038/s41598-019-43499-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 04/25/2019] [Indexed: 12/05/2022] Open
Abstract
The Fukushima Daiichi nuclear power plant accident caused serious radiocesium (137Cs) contamination of the soil in multiple terrestrial ecosystems. Soil is a complex system where minerals, organic matter, and microorganisms interact with each other; therefore, an improved understanding of the interactions of 137Cs with these soil constituents is key to accurately assessing the environmental consequences of the accident. Soil samples were collected from field, orchard, and forest sites in July 2011, separated into three soil fractions with different mineral–organic interaction characteristics using a density fractionation method, and then analyzed for 137Cs content, mineral composition, and organic matter content. The results show that 20–71% of the 137Cs was retained in association with relatively mineral-free, particulate organic matter (POM)-dominant fractions in the orchard and forest surface soil layers. Given the physicochemical and mineralogical properties and the 137Cs extractability of the soils, 137Cs incorporation into the complex structure of POM is likely the main mechanism for 137Cs retention in the surface soil layers. Therefore, our results suggest that a significant fraction of 137Cs is not immediately immobilized by clay minerals and remains potentially mobile and bioavailable in surface layers of organic-rich soils.
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Affiliation(s)
- Jun Koarashi
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan.
| | - Syusaku Nishimura
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan.,Tono Geoscience Center, Japan Atomic Energy Agency, Gifu, 509-5102, Japan
| | - Mariko Atarashi-Andoh
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Kotomi Muto
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Takeshi Matsunaga
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
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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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22
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Low 137Cs retention capability of organic layers in Japanese forest ecosystems affected by the Fukushima nuclear accident. J Radioanal Nucl Chem 2019. [DOI: 10.1007/s10967-019-06435-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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23
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Tsvetnova O, Shcheglov A, Klyashtorin A. 137Cs and K annual fluxes in a cropland and forest ecosystems twenty-four years after the Chernobyl accident. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 195:79-89. [PMID: 30296689 DOI: 10.1016/j.jenvrad.2018.09.019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 08/24/2018] [Accepted: 09/22/2018] [Indexed: 06/08/2023]
Abstract
Biological cycles of the Chernobyl originated cesium-137 (137Cs, radiocesium) and the natural potassium (K) in oak, birch, and pine forest, and wheat cropland in Russian Federation, approximately 500 km northeast of the Chernobyl Nuclear Power Plant, were subject to a multiyear monitoring. By 2010, the annual return of 137Cs from forest vegetation to the soil in dead tree components still exceeds its annual accumulation in the tree phytomass by a factor of 4-6, apparently due to residual surface contamination in the external bark and the ongoing process of tree stand decontamination following the initial fallout. In the cropland, both ascending and descending fluxes of 137Cs are close to the steady state. The annual accumulation of 137Cs in the tree biomass was the highest in the oak forest and the lowest in the pine forest. The annual K accumulation was the highest in the cropland and the lowest in the pine forest.
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Affiliation(s)
- Ol'ga Tsvetnova
- Moscow Lomonosov State University, Soil Science Department, Moscow, Russia, 119991.
| | - Alexey Shcheglov
- Moscow Lomonosov State University, Soil Science Department, Moscow, Russia, 119991.
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24
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Hao WM, Baker S, Lincoln E, Hudson S, Lee SD, Lemieux P. Cesium emissions from laboratory fires. JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION (1995) 2018; 68:1211-1223. [PMID: 29953328 PMCID: PMC6200644 DOI: 10.1080/10962247.2018.1493001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 05/16/2018] [Accepted: 06/21/2018] [Indexed: 06/08/2023]
Abstract
If a radiological incident such as a nuclear power plant accident, a radiological dispersal device, or detonation of an improvised nuclear device occurs, significant areas may be contaminated. Initial cleanup priorities would likely focus on populated areas, leaving the forested areas to pass several seasons where the overhead canopy materials would fall to the forest floor. In the event of a wildfire in a radionuclide-contaminated forest, some radionuclides would be emitted in the air while the rest would remain in the ash. This paper reports on a laboratory simulation study that examines the partitioning of cesium-133 (a nonradioactive isotope of cesium) between airborne particulate matter and residual nonentrained ash when pine needles and peat are doped with cesium. Only 1-2.5% of the doped cesium in pine needles was emitted as particulate matter, and most of the cesium was concentrated in the particulate fraction greater than 10 µm in aerodynamic diameter. For peat fires, virtually all of the cesium remained in the ash. The results from this study will be used for modeling efforts to assess potential exposure risks to firefighters and the surrounding public. Implications: There is a potential for emissions of radionuclides such as cesium-137 from a wildfire over a radionuclide-contaminated forest. This paper reports on a laboratory simulation study of a wildfire with two types of biomass doped with nonradioactive cesium. This simulation suggests that only 1-2.5% of the cesium in the biomass will be emitted from the wildfire, while the rest will reside in the residual ash. In this study, pine needles were the only contributor to the air emissions of cesium; duff was not a source of cesium emissions. In this study, cesium emitted from the simulated wildfire was concentrated in the particle sizes larger than 10 µm.
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Affiliation(s)
- Wei Min Hao
- Missoula Fire Sciences Laboratory, Rocky Mountain Research Station, US Forest Service, Missoula, Montana, USA
| | - Stephen Baker
- Missoula Fire Sciences Laboratory, Rocky Mountain Research Station, US Forest Service, Missoula, Montana, USA
| | - Emily Lincoln
- Missoula Fire Sciences Laboratory, Rocky Mountain Research Station, US Forest Service, Missoula, Montana, USA
| | - Scott Hudson
- Consequence Management Advisory Division, Office of Emergency Management, US Environmental Protection Agency, Erlanger, KY, USA
| | - Sang Don Lee
- Decontamination and Consequence Management Division, National Homeland Security Research Center, US Environmental Protection Agency, Research Triangle Park, NC, USA
| | - Paul Lemieux
- Decontamination and Consequence Management Division, National Homeland Security Research Center, US Environmental Protection Agency, Research Triangle Park, NC, USA
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25
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Kurita K, Yamaguchi M, Nagao Y, Suzui N, Yin YG, Yoshihara T, Kawachi N. Development of an Easy and Simple Method to Measure the Environmental Radioactivity in Trees with Efficient Personal Dosimeters. ACTA ACUST UNITED AC 2018. [DOI: 10.3769/radioisotopes.67.427] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Keisuke Kurita
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
| | - Mitsutaka Yamaguchi
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
| | - Yuto Nagao
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
| | - Nobuo Suzui
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
| | - Yong-Gen Yin
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
| | - Toshihiro Yoshihara
- Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI)
| | - Naoki Kawachi
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
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26
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Yoschenko V, Takase T, Hinton TG, Nanba K, Onda Y, Konoplev A, Goto A, Yokoyama A, Keitoku K. Radioactive and stable cesium isotope distributions and dynamics in Japanese cedar forests. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 186:34-44. [PMID: 29029765 DOI: 10.1016/j.jenvrad.2017.09.026] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Revised: 09/26/2017] [Accepted: 09/26/2017] [Indexed: 06/07/2023]
Abstract
Dynamics of the Fukushima-derived radiocesium and distribution of the natural stable isotope 133Cs in Japanese cedar (Cryptomeria japonica D. Don) forest ecosystems were studied during 2014-2016. For the experimental site in Yamakiya, Fukushima Prefecture, we present the redistribution of radiocesium among ecosystem compartments during the entire observation period, while the results obtained at another two experimental site were used to demonstrate similarity of the main trends in the Japanese forest ecosystems. Our observations at the Yamakiya site revealed significant redistribution of radiocesium between the ecosystem compartments during 2014-2016. During this same period radionuclide inventories in the aboveground tree biomass were relatively stable, however, radiocesium in forest litter decreased from 20 ± 11% of the total deposition in 2014 to 4.6 ± 2.7% in 2016. Radiocesium in the soil profile accumulated in the 5-cm topsoil layers. In 2016, more than 80% of the total radionuclide deposition in the ecosystem resided in the 5-cm topsoil layer. The radiocesium distribution between the aboveground biomass compartments at Yamakiya during 2014-2016 was gradually approaching a quasi-equilibrium distribution with stable cesium. Strong correlations of radioactive and stable cesium isotope concentrations in all compartments of the ecosystem have not been reached yet. However, in some compartments the correlation is already strong. An increase of radiocesium concentrations in young foliage in 2016, compared to 2015, and an increase in 2015-2016 of the 137Cs/133Cs concentration ratio in the biomass compartments with strong correlations indicate an increase in root uptake of radiocesium from the soil profile. Mass balance of the radionuclide inventories, and accounting for radiocesium fluxes in litterfall, throughfall and stemflow, enabled a rough estimate of the annual radiocesium root uptake flux as 2 ± 1% of the total inventory in the ecosystem.
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Affiliation(s)
- Vasyl Yoschenko
- Institute of Environmental Radioactivity of Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan.
| | - Tsugiko Takase
- Institute of Environmental Radioactivity of Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
| | - Thomas G Hinton
- Institute of Environmental Radioactivity of Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
| | - Kenji Nanba
- Institute of Environmental Radioactivity of Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tsukuba, Ibaraki Prefecture, 305-8572, Japan
| | - Alexei Konoplev
- Institute of Environmental Radioactivity of Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
| | - Azusa Goto
- Institute of Environmental Radioactivity of Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
| | - Aya Yokoyama
- Institute of Environmental Radioactivity of Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
| | - Koji Keitoku
- Institute of Environmental Radioactivity of Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
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27
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Teramage MT, Carasco L, Orjollet D, Coppin F. The impact of radiocesium input forms on its extractability in Fukushima forest soils. JOURNAL OF HAZARDOUS MATERIALS 2018; 349:205-214. [PMID: 29427971 DOI: 10.1016/j.jhazmat.2018.01.047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 01/22/2018] [Indexed: 06/08/2023]
Abstract
The effects of 137Cs deposit forms on its ageing in soil have not yet been reported. Soluble and Solid 137Cs input forms were mixed with the mineral soils collected under Fukushima's coniferous and broadleaf forests, incubated under controlled laboratory, and examined the evolution of 137Cs availability over time. Results show that the extracted 137Cs fraction with water was less than 1% for the soluble input form and below detection limit for the solid input forms. Likewise, with an acetate reagent, the extracted 137Cs fraction ranged from 46 to 56% for the soluble input and from 2 to 15% for the solid input, implying that the nature of the 137Cs contamination strongly influences its extractability and mobility in soil. Although the degradation of organic materials was apparent, its impact on the 137Cs extractability was found to be weak. Nevertheless, more Ac-available 137Cs was obtained from broadleaf organic material mixes than the coniferous counterparts, suggesting that the lignified nature of latter tend to retain more 137Cs. When extrapolated to a field context, more available 137Cs fraction may be expected from wet-derived contaminated forest soils than contaminated via solid-derived inputs. Such information could be helpful for radioecological management schemes in contaminated forest environments.
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Affiliation(s)
- Mengistu T Teramage
- Institute of Radiological Protection and Nuclear Safety (IRSN), PSE-ENV, SRTE, LR2T, CE Cadarache, 13115, Saint Paul les Durance Cedex, France.
| | - Loic Carasco
- Institute of Radiological Protection and Nuclear Safety (IRSN), PSE-ENV, SRTE, LR2T, CE Cadarache, 13115, Saint Paul les Durance Cedex, France
| | - Daniel Orjollet
- Institute of Radiological Protection and Nuclear Safety (IRSN), PSE-ENV, SRTE, LR2T, CE Cadarache, 13115, Saint Paul les Durance Cedex, France
| | - Frederic Coppin
- Institute of Radiological Protection and Nuclear Safety (IRSN), PSE-ENV, SRTE, LR2T, CE Cadarache, 13115, Saint Paul les Durance Cedex, France
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28
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Sakuma K, Tsuji H, Hayashi S, Funaki H, Malins A, Yoshimura K, Kurikami H, Kitamura A, Iijima K, Hosomi M. Applicability of K d for modelling dissolved 137Cs concentrations in Fukushima river water: Case study of the upstream Ota River. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 184-185:53-62. [PMID: 29353199 DOI: 10.1016/j.jenvrad.2018.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 12/25/2017] [Accepted: 01/04/2018] [Indexed: 06/07/2023]
Abstract
A study is presented on the applicability of the distribution coefficient (Kd) absorption/desorption model to simulate dissolved 137Cs concentrations in Fukushima river water. The upstream Ota River basin was simulated using GEneral-purpose Terrestrial Fluid-flow Simulator (GETFLOWS) for the period 1 January 2014 to 31 December 2015. Good agreement was obtained between the simulations and observations on water and suspended sediment fluxes, and on particulate bound 137Cs concentrations under both base and high flow conditions. By contrast the measured concentrations of dissolved 137Cs in the river water were much harder to reproduce with the simulations. By tuning the Kd values for large particles, it was possible to reproduce the mean dissolved 137Cs concentrations during base flow periods (observation: 0.32 Bq/L, simulation: 0.36 Bq/L). However neither the seasonal variability in the base flow dissolved 137Cs concentrations (0.14-0.53 Bq/L), nor the peaks in concentration that occurred during storms (0.18-0.88 Bq/L, mean: 0.55 Bq/L), could be reproduced with realistic simulation parameters. These discrepancies may be explained by microbial action and leaching from organic matter in forest litter providing an additional input of dissolved 137Cs to rivers, particularly over summer, and limitations of the Kd absorption/desorption model. It is recommended that future studies investigate these issues in order to improve simulations of dissolved 137Cs concentrations in Fukushima rivers.
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Affiliation(s)
- Kazuyuki Sakuma
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588, Japan.
| | - Hideki Tsuji
- Fukushima Branch, National Institute of Environmental Studies, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Seiji Hayashi
- Fukushima Branch, National Institute of Environmental Studies, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Hironori Funaki
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Alex Malins
- Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Kazuya Yoshimura
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Hiroshi Kurikami
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Akihiro Kitamura
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan; Center for Computational Science & e-Systems, Japan Atomic Energy Agency, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa-shi, Chiba 277-0871, Japan
| | - Kazuki Iijima
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, 10-2, Fukasaku, Miharu-machi, Tamura-gun, Fukushima 963-7700, Japan
| | - Masaaki Hosomi
- Department of Chemical Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka, Koganei, Tokyo 184-8588, Japan
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29
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Tsuchiya R, Taira Y, Orita M, Fukushima Y, Endo Y, Yamashita S, Takamura N. Radiocesium contamination and estimated internal exposure doses in edible wild plants in Kawauchi Village following the Fukushima nuclear disaster. PLoS One 2017; 12:e0189398. [PMID: 29240794 PMCID: PMC5730164 DOI: 10.1371/journal.pone.0189398] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/26/2017] [Indexed: 11/19/2022] Open
Abstract
Kawauchi Village, in Fukushima Prefecture, is located within a 30-km radius of the nuclear disaster site of the Fukushima Daiichi Nuclear Power Plant (FDNPP). "Sansai" (edible wild plants) in this village have been evaluated by gamma spectrometry after the residents had returned to their homes, to determine the residents' risk of internal exposure to artificial radionuclides due to consumption of these plants. The concentrations of radiocesium (cesium-134 and cesium-137) were measured in all 364 samples collected in spring 2015. Overall, 34 (9.3%) samples exceeded the regulatory limit of 100 Bq/kg established by Japanese guidelines, 80 (22.0%) samples registered between 100 Bq/kg and 20 Bq/kg, and 250 (68.7%) registered below 20 Bq/kg (the detection limit). The internal effective doses from edible wild plants were sufficiently low (less than 1 mSv/y), at 3.5±1.2 μSv/y for males and 3.2±0.9 μSv/y for females (2.7±1.5 μSv/y for children and 3.7±0.7 μSv/y for adults in 2015). Thus, the potential internal exposure doses due to consumption of these edible wild plants were below the applicable radiological standard limits for foods. However, high radiocesium levels were confirmed in specific species, such as Eleutherococcus sciadophylloides ("Koshiabura") and Osmunda japonica (Asian royal fern, "Zenmai"). Consequently, a need still might exist for long-term follow-up such as environmental monitoring, physical and mental support to avoid unnecessary radiation exposure and to remove anxiety about adverse health effects due to radiation. The customs of residents, especially the "satoyama" (countryside) culture of ingesting "sansai," also require consideration in the further reconstruction of areas such as Kawauchi Village that were affected by the nuclear disaster.
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Affiliation(s)
- Rimi Tsuchiya
- Department of Global Health, Medicine and Welfare, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Yasuyuki Taira
- Department of Global Health, Medicine and Welfare, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Makiko Orita
- Department of Global Health, Medicine and Welfare, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Yoshiko Fukushima
- Department of Nursing, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Yuukou Endo
- Kawauchi Municipal Government, Fukushima, Japan
| | - Shunichi Yamashita
- Department of Radiation Medical Science, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Noboru Takamura
- Department of Global Health, Medicine and Welfare, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
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30
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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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