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Tani T, Satoh Y. Development of a carbon accumulation model for estimating the concentration of 14C in Japanese radish. J NUCL SCI TECHNOL 2022. [DOI: 10.1080/00223131.2022.2123407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Affiliation(s)
- Takashi Tani
- Department of Radioecology, Institute for Environmental Sciences, Aomori, Japan
| | - Yuhi Satoh
- Department of Radioecology, Institute for Environmental Sciences, Aomori, Japan
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Imada S, Tako Y, Moriya Y. DIRECT ASSIMILATION OF ATMOSPHERIC CARBON BY IMMATURE APPLE FRUITS. RADIATION PROTECTION DOSIMETRY 2022; 198:1004-1008. [PMID: 36083727 DOI: 10.1093/rpd/ncac034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 02/01/2022] [Accepted: 02/09/2022] [Indexed: 06/15/2023]
Abstract
Although fruit development primarily depends on photoassimilation by leaves, immature green fruits can also directly assimilate atmospheric CO2. To elucidate the process of C accumulation due to direct assimilation by fruit, we conducted a 13CO2 exposure experiment in an orchard in late June with immature 'Fuji' apples (Malus domestica). Four fruits from three trees were enclosed in transparent plastic bags and exposed to 13CO2 using an in-situ exposure system. Fruits were collected prior to and immediately following exposure in early July, late September and mid-November, and 13C concentrations in the peduncle, skin, flesh and core (including seeds) were measured. The higher assimilated 13C concentrations measured following exposure indicated that the fruits directly assimilated atmospheric 13C. The 13C concentration in fruit skin was higher immediately after exposure and in early July compared with that prior to exposure. In late September and mid-November, 13C concentrations were close to natural levels.
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Affiliation(s)
- Shogo Imada
- Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Kamikita, Aomori 039-3212, Japan
| | - Yasuhiro Tako
- Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Kamikita, Aomori 039-3212, Japan
| | - Yuki Moriya
- Division of Fruit Tree Production Research, Institute of Fruit Tree and Tea Science, NARO, 92-24 Nabeyashiki, Shimokuriyagawa, Morioka, Iwate 020-0123, Japan
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Yadav P, Le Dizès S. Intercomparison of model predictions of 14C concentrations in agricultural plants following acute exposures to airborne 14C. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2022; 248:106886. [PMID: 35472689 DOI: 10.1016/j.jenvrad.2022.106886] [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: 12/28/2021] [Revised: 03/24/2022] [Accepted: 04/07/2022] [Indexed: 06/14/2023]
Abstract
Carbon-14 (14C) is one of the main radionuclides released during normal operation by nuclear power plants, nuclear defense facilities and nuclear fuel reprocessing plants. It is mainly released in the form of carbon dioxide gas denoted 14CO2, which has the specificity of being incorporated into food webs via photosynthesis by primary producing organisms. In order to better assess the environmental and human impacts of 14CO2 under normal operating conditions - or after potential accidental releases - from nuclear facilities, it is necessary to improve our understanding and our predictions of the behaviour of this radionuclide along the human food chain. To achieve this goal, the International Atomic Energy Agency (IAEA) Environmental Modelling for Radiation Safety (EMRAS) model evaluation programme included the Tritium and 14C Working Group (TCWG) which dealt with the intercomparison exercises between several models of environmental transfer in the case of routine and accidental releases of these radionuclides into the environment, and their performance testing. The TOCATTA-χ model developed at IRSN is a dynamic compartment model with high temporal resolution, which simulates the transfer of 14C (and tritium) in grassland ecosystems exposed to gaseous 14CO2 (and HTO) from nuclear facilities under normal or accidental operating conditions. Following this work, IRSN proposed a related project to extend the application of the TOCATTA-χ model to 14C estimates in leafy vegetables, fruits and roots. This article deals with the application of the TOCATTA-χ model to a specific real-case scenario identified within the framework of the TCWG. The scenario provides experimental data and predicted results from models developed at the international level. Model-model and model-data intercomparison exercises were thus carried out to validate the evaluations of the TOCATTA-χ model. In addition, this paper discusses the parameterization of the TOCATTA-χ model for this scenario and the development of modules for 14C concentrations in potato tubers, based on the assumption that photosynthetic transfer occurs directly from leaves to tubers and depends mainly on the growth stage of the tubers. It is observed that the predictions of the TOCATTA-χ model for the concentrations of 14C in leaves and tubers are slightly better than the other models due to the modelling approaches adopted by TOCATTA-χ for the calculation of key ecophysiological processes that govern plant functioning. Overall, the TOCATTA-χ model reduces the Root Mean Square Error (RMSE) by a factor of less than 8 compared to other models. In addition, most of the predicted results of the TOCATTA-χ model better match the measurements and are within the measurement uncertainty limit, while a few are overestimated. This could be due to the high uncertainty associated with the experimentally measured 14C activities, which reflects the field variability in plant growth rate.
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Affiliation(s)
- Pratibha Yadav
- Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Reactor Safety Division, Bautzner Landstrasse 400, 01328, Dresden, Germany; Institut de Radioprotection et de Sûrete Nucleaire (IRSN), PSE-ENV/SRTE/LR2T, Laboratoire de Recherche sur les Transferts des radionucleides dans les écosystèmes Terrestres, CEN Cadarache, Saint Paul Lez Durance, 13115, France.
| | - Séverine Le Dizès
- Institut de Radioprotection et de Sûrete Nucleaire (IRSN), PSE-ENV/SRTE/LR2T, Laboratoire de Recherche sur les Transferts des radionucleides dans les écosystèmes Terrestres, CEN Cadarache, Saint Paul Lez Durance, 13115, France
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Imada S, Tani T, Tako Y, Moriya Y, Hisamatsu S. In situ experimental exposure of fruit-bearing shoots of apple trees to 13CO 2 and construction of a dynamic transfer model of carbon. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2021; 233:106595. [PMID: 33827008 DOI: 10.1016/j.jenvrad.2021.106595] [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: 12/09/2020] [Revised: 03/13/2021] [Accepted: 03/18/2021] [Indexed: 06/12/2023]
Abstract
Evaluating the transfer and metabolism of carbon (C) in apple fruit is key to estimating the potential accumulation of atmospheric 14C in fruit near and around nuclear facilities. We developed a dynamic compartment model for apple fruit-bearing shoots, assuming that the shoots are a simple unit of source and sink for photoassimilates. Fruit-bearing shoots of Malus domestica "Fuji" at different fruit growth stages were exposed to 13CO2in situ, followed by sampling at 72 h after exposure or at harvest. The 13C/(13C+12C) mole ratio in fruits, leaves, and current branch were measured to construct a five-compartment model of 13C (fruit, each fast and slow component of leaves, and current branch). The C inventories in the compartments were presented in accordance with the measured growth curves of C in the organs. The model simulated the 13C dynamics in plant tissues well. Simulation results of photoassimilate distribution using the model indicated that the retention of photoassimilated C at the harvest depended on the growth rate of C in the organs at the exposure.
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Affiliation(s)
- Shogo Imada
- Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Kamikita, Aomori, 039-3212, Japan.
| | - Takashi Tani
- Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Kamikita, Aomori, 039-3212, Japan
| | - Yasuhiro Tako
- Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Kamikita, Aomori, 039-3212, Japan
| | - Yuki Moriya
- Division of Apple Research, Institute of Fruit Tree and Tea Science, NARO, Nabeyashiki-92 Shimokuriyagawa, Morioka, Iwate, 020-0123, Japan
| | - Shun'ichi Hisamatsu
- Department of Radioecology, Institute for Environmental Sciences, 1-7 Ienomae, Obuchi, Rokkasho, Kamikita, Aomori, 039-3212, Japan
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Ota M, Tanaka T. Importance of root uptake of 14CO 2 on 14C transfer to plants impacted by below-ground 14CH 4 release. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 201:5-18. [PMID: 30721755 DOI: 10.1016/j.jenvrad.2019.01.012] [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: 12/25/2018] [Revised: 01/24/2019] [Accepted: 01/24/2019] [Indexed: 06/09/2023]
Abstract
14C-labelled methane (14CH4) released from deep underground radioactive waste disposal facilities can be a below-ground source of 14CO2 owing to microbial oxidation of 14CH4 to 14CO2 in soils. Environmental 14C models assume that the transfer of 14CO2 from soil to plant occurs via foliar uptake of 14CO2. Nevertheless, the importance of 14CO2 root uptake is not well understood. In the present study, below-ground transport and oxidation of 14CH4 were modeled and incorporated into an existing land-surface 14CO2 model (SOLVEG-II) to assess the relative importance of root uptake and foliar uptake on 14CO2 transfer from soil to plants. Performance of the model in calculating the below-ground dynamics of 14CH4 was validated by simulating a field experiment of 13CH4 (as a substitute for 14CH4) injection into subsoil in a wheat field in the UK. The proposed model simulation was then applied to 14C transfer in a hypothetical ecosystem impacted by continuous 14CH4 input from the water table (bottom of 1-m thick soil), which simulated continuous release of 14CH4 from a deep underground radioactive waste disposal facility. The contrast between the results obtained from the model calculation that assumed different distributions of roots (rooting depths of 11 cm, or 97 cm) and methane oxidation (characterized by e-folding depths of 5 cm, 20 cm, or 80 cm) in the soil provided insight into the relative importance of root uptake and foliar uptake pathways. In the shallowly rooted ecosystem with rooting depth of 11 cm, foliar uptake of 14CO2 was significant, accounting for 80% of the 14C accumulation (as organic 14C) in the plant (leaf compartment). By contrast, in a deeply rooted ecosystem (rooting depth of 97 cm), where the root penetrated to depths close to the water-table, more than half (63%) the 14C accumulated in the plant was transferred via the root uptake pathway. We found that 14CO2 root uptake (thus 14C accumulation in the plant) in this ecosystem depended on the distribution of methane oxidation in the soil; all 14C accumulated in the plant was transferred by the root uptake pathway when methane oxidation occurred at considerable depths (e-folding depths of 20 cm, or 80 cm) in the soil. The high level of 14CO2 root uptake was ascribed to the oxidation of added 14CH4 (i.e., production of 14CO2) in the deep part of the soil and the subsequent high level of root uptake of the deep soil-water containing 14CO2. These results indicate that 14CO2 root uptake contributes significantly to 14CO2 transfer to plants if 14CH4 oxidation occurs at great depths and roots penetrate deeply into the soil. It is recommended that current environmental 14C models must be refined to consider the importance of the root uptake pathway to ensure that dose estimates of 14CH4 release from deep underground waste disposal facilities are accurate.
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Affiliation(s)
- Masakazu Ota
- Research Group for Environmental Science, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan.
| | - Taku Tanaka
- Group P78, Laboratoire National d'Hydraulique et Environnement, Électricité de France, 6 Quai Watier, Chatou, 78401, France
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Melintescu A, Galeriu D, Diabaté S, Strack S. Preparatory Steps for a Robust Dynamic Model for Organically Bound Tritium Dynamics in Agricultural Crops. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst14-t59] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- A. Melintescu
- “Horia Hulubei” National Institute for Physics and Nuclear Engineering, 30 Reactorului St., POB MG-6, Bucharest – Magurele, RO-077125, Romania
| | - D. Galeriu
- “Horia Hulubei” National Institute for Physics and Nuclear Engineering, 30 Reactorului St., POB MG-6, Bucharest – Magurele, RO-077125, Romania
| | - S. Diabaté
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen Germany
| | - S. Strack
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), 76344 Eggenstein-Leopoldshafen Germany
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Galeriu D, Melintescu A. Progresses in Tritium Accident Modelling in the Frame of IAEA EMRAS II. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst14-t26] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- D. Galeriu
- “Horia Hulubei” National Institute of Physics and Nuclear Engineering, 407 Atomistilor St., POB MG-6, Bucharest–Magurele, RO-077125, Romania
| | - A. Melintescu
- “Horia Hulubei” National Institute of Physics and Nuclear Engineering, 407 Atomistilor St., POB MG-6, Bucharest–Magurele, RO-077125, Romania
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Ota M, Katata G, Nagai H, Terada H. Impacts of C-uptake by plants on the spatial distribution of 14C accumulated in vegetation around a nuclear facility-Application of a sophisticated land surface 14C model to the Rokkasho reprocessing plant, Japan. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 162-163:189-204. [PMID: 27267157 DOI: 10.1016/j.jenvrad.2016.05.032] [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: 02/09/2016] [Revised: 05/24/2016] [Accepted: 05/29/2016] [Indexed: 06/06/2023]
Abstract
The impacts of carbon uptake by plants on the spatial distribution of radiocarbon (14C) accumulated in vegetation around a nuclear facility were investigated by numerical simulations using a sophisticated land surface 14C model (SOLVEG-II). In the simulation, SOLVEG-II was combined with a mesoscale meteorological model and an atmospheric dispersion model. The model combination was applied to simulate the transfer of 14CO2 and to assess the radiological impact of 14C accumulation in rice grains during test operations of the Rokkasho reprocessing plant (RRP), Japan, in 2007. The calculated 14C-specific activities in rice grains agreed with the observed activities in paddy fields around the RRP within a factor of four. The annual effective dose delivered from 14C in the rice grain was estimated to be less than 0.7 μSv, only 0.07% of the annual effective dose limit of 1 mSv for the public. Numerical experiments of hypothetical continuous atmospheric 14CO2 release from the RRP showed that the 14C-specific activities of rice plants at harvest differed from the annual mean activities in the air. The difference was attributed to seasonal variations in the atmospheric 14CO2 concentration and the growth of the rice plant. Accumulation of 14C in the rice plant significantly increased when 14CO2 releases were limited during daytime hours, compared with the results observed during the nighttime. These results indicated that plant growth stages and diurnal photosynthesis should be considered in predictions of the ingestion dose of 14C for long-term chronic releases and short-term diurnal releases of 14CO2, respectively.
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Affiliation(s)
- Masakazu Ota
- Research Group for Environmental Science, Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan.
| | - Genki Katata
- Research Group for Environmental Science, Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan
| | - Haruyasu Nagai
- Research Group for Environmental Science, Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan
| | - Hiroaki Terada
- Research Group for Environmental Science, Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Tokai, Ibaraki, 319-1195, Japan
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Mihok S, Wilk M, Lapp A, St-Amant N, Kwamena NOA, Clark ID. Tritium dynamics in soils and plants grown under three irrigation regimes at a tritium processing facility in Canada. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 153:176-187. [PMID: 26773512 DOI: 10.1016/j.jenvrad.2015.12.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Revised: 12/27/2015] [Accepted: 12/28/2015] [Indexed: 06/05/2023]
Abstract
The dynamics of tritium released from nuclear facilities as tritiated water (HTO) have been studied extensively with results incorporated into regulatory assessment models. These models typically estimate organically bound tritium (OBT) for calculating public dose as OBT itself is rarely measured. Higher than expected OBT/HTO ratios in plants and soils are an emerging issue that is not well understood. To support the improvement of models, an experimental garden was set up in 2012 at a tritium processing facility in Pembroke, Ontario to characterize the circumstances under which high OBT/HTO ratios may arise. Soils and plants were sampled weekly to coincide with detailed air and stack monitoring. The design included a plot of native grass/soil, contrasted with sod and vegetables grown in barrels with commercial topsoil under natural rain and either low or high tritium irrigation water. Air monitoring indicated that the plume was present infrequently at concentrations of up to about 100 Bq/m(3) (the garden was not in a major wind sector). Mean air concentrations during the day on workdays (HTO 10.3 Bq/m(3), HT 5.8 Bq/m(3)) were higher than at other times (0.7-2.6 Bq/m(3)). Mean Tissue Free Water Tritium (TFWT) in plants and soils and OBT/HTO ratios were only very weakly or not at all correlated with releases on a weekly basis. TFWT was equal in soils and plants and in above and below ground parts of vegetables. OBT/HTO ratios in above ground parts of vegetables were above one when the main source of tritium was from high tritium irrigation water (1.5-1.8). Ratios were below one in below ground parts of vegetables when irrigated with high tritium water (0.4-0.6) and above one in vegetables rain-fed or irrigated with low tritium water (1.3-2.8). In contrast, OBT/HTO ratios were very high (9.0-13.5) when the source of tritium was mainly from the atmosphere. TFWT varied considerably through time as a result of SRBT's operations; OBT/HTO ratios showed no clear temporal pattern in above or below ground plant parts. Native soil after ∼20 years of operations at SRBT had high initial OBT that persisted through the growing season; little OBT formed in garden plot soil during experiments. High OBT in native soil appeared to be a signature of higher past releases at SRBT. This phenomenon was confirmed in soils obtained at another processing facility in Canada with a similar history. The insights into variation in OBT/HTO ratios found here are of regulatory interest and should be incorporated in assessment models to aid in the design of relevant environmental monitoring programs for OBT.
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Affiliation(s)
- S Mihok
- Canadian Nuclear Safety Commission, 280 Slater Street, P.O. Box 1046, Station B, Ottawa, Ontario K1P 5S9, Canada.
| | - M Wilk
- Department of Earth Sciences, 140 Louis-Pasteur, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - A Lapp
- Department of Earth Sciences, 140 Louis-Pasteur, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - N St-Amant
- Canadian Nuclear Safety Commission, 280 Slater Street, P.O. Box 1046, Station B, Ottawa, Ontario K1P 5S9, Canada
| | - N-O A Kwamena
- Canadian Nuclear Safety Commission, 280 Slater Street, P.O. Box 1046, Station B, Ottawa, Ontario K1P 5S9, Canada
| | - I D Clark
- Department of Earth Sciences, 140 Louis-Pasteur, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
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