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Bodereau N, Eyrolle F, Copard Y, Dumoulin JP, Lepage H, Giner F, Mourier D, Gurriaran R. Carbon-14 cycling in a nuclearized river: A first study in the downstream part of the Rhône River (France). THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 954:176502. [PMID: 39362556 DOI: 10.1016/j.scitotenv.2024.176502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2024] [Revised: 09/20/2024] [Accepted: 09/23/2024] [Indexed: 10/05/2024]
Abstract
Carbon-14 (14C) has a natural origin but is also anthropogenically released from civil nuclear facilities. Due to its long decay period (half-life: 5700 ± 30 years), it is a persistent radionuclide in the environment. In rivers, the complex speciation of carbon makes the fate of industrial 14C difficult to track. This study reports a first overview of artificial 14C cycling in a nuclearized river. A one-year sampling campaign was conducted on the French nuclearized Rhône River and two of its non-nuclearized tributaries (Durance and Ardèche rivers). Isotopic (δ13C, Δ14C) and carbon concentrations analyses were performed on the particulate organic carbon (POC), dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC). Chlorophyll-a (Chl-a) and tritium analyses were performed to assess the dynamic of aquatic organic matter and the nuclear industry contribution, respectively. Comparisons of Δ14C data obtained from the Rhône River with those from the tributaries highlight significant industrial radiocarbon labelling in all carbon forms, with medians of 142, 130 and 42 ‰ for POC, DOC and DIC, that are 2-3 times higher than those of the tributaries. The high values of Chl-a/POC ratios with Δ14C-enriched POC suggest a biological uptake of artificial Δ14C in DIC by aquatic photosynthesis. The relationship of Δ14C-DIC with tritium activity indicates a response to recent releases and enables the contribution of nuclear power plants to be estimated at a median of 26 %. Sampling at the Rhône's mouth would reinforce our understanding of the fate of riverine 14C when entering the marine environment.
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Affiliation(s)
- Nathan Bodereau
- IRSN, PSE-ENV/STAAR/LRTA, BP 159, CEA Cadarache, 13115 Saint-Paul-les-Durance, France; BRGM, DNG/TIA, BP 36009, 45060 Orléans, France.
| | - Frederique Eyrolle
- IRSN, PSE-ENV/STAAR/LRTA, BP 159, CEA Cadarache, 13115 Saint-Paul-les-Durance, France
| | - Yoann Copard
- Normandie Univ, UNIROUEN, UNICAEN, UMR CNRS 6143 M2C, Place Blondel, 76130 Mont-Saint-Aignan, France
| | - Jean-Pascal Dumoulin
- Laboratoire de Mesure du Carbone 14 (LMC14), Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNRS-UVSQ, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - Hugo Lepage
- IRSN, PSE-ENV/STAAR/LRTA, BP 159, CEA Cadarache, 13115 Saint-Paul-les-Durance, France
| | - Franck Giner
- IRSN, PSE-ENV/STAAR/LRTA, BP 159, CEA Cadarache, 13115 Saint-Paul-les-Durance, France
| | - David Mourier
- IRSN, PSE-ENV/STAAR/LRTA, BP 159, CEA Cadarache, 13115 Saint-Paul-les-Durance, France
| | - Rodolfo Gurriaran
- IRSN, PSE-ENV/STAAR/LRTA, BP 159, CEA Cadarache, 13115 Saint-Paul-les-Durance, France
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Khamanek K, Khuntong S, Saenboonruang K, Toyen D, Chantarot C, Yongprawat M, Saengkorakot C, Phattanasub A, Krisanangkura P, Hazama R, Rittirong A, Sudprasert W. Assessing tritium contamination in Thailand's rainwater: A study of environmental monitoring and nuclear surveillance. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2023; 262:107151. [PMID: 36913797 DOI: 10.1016/j.jenvrad.2023.107151] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/24/2023] [Accepted: 03/05/2023] [Indexed: 06/18/2023]
Abstract
Tritium, whether naturally occurring or caused by human nuclear activity, can result in a large amount of tritium contamination in the environment, especially in the water cycle, causing a high concentration of tritium in rainfall. The objective of this research was to measure the level of tritium in the environment from rainfall in two different areas as a basis for monitoring tritium contamination in the environment. Rainwater samples were collected in Thailand every 24 h for a period of 1 year during 2021-2022 at the Kasetsart University Station, Sriracha Campus, Chonburi province and at the Mae Hia Agricultural Meteorological Station, Chiang Mai province. The tritium levels were measured in rainwater samples using the electrolytic enrichment method combined with liquid scintillation counting. The chemical composition of the rainwater was analyzed based on ion chromatography. The results (presented with ± combined uncertainty) showed that the tritium content in the rainwater samples at Kasetsart University Station Sriracha Campus was in the range 0.9 ± 0.2-1.6 ± 0.3 TU (0.11 ± 0.02-0.19 ± 0.03 Bq.L-1). The mean concentration was 1.0 ± 0.2 TU (0.12 ± 0.03 Bq.L-1). The most common ions found in the rainwater samples were SO42-, Ca2+, and NO3-, with mean concentrations of 1.52 ± 0.82, 1.08 ± 0.51, and 1.05 ± 0.78 mg.L-1, respectively. The tritium content in rainwater collected from the Mae Hia Agricultural Meteorological Station was in the range 1.6 ± 0.2-4.9 ± 0.4 TU (0.19 ± 0.02-0.58 ± 0.05 Bq.L-1). The mean concentration was 2.4 ± 0.4 TU (0.28 ± 0.05 Bq.L-1). The most common ions found in the rainwater were NO3-, Ca2+, and SO42-, with mean concentrations of 1.21 ± 1.02, 0.67 ± 0.43, and 0.54 ± 0.41 mg.L-1, respectively. The tritium concentration in the rainwater at both stations differed but remained at a natural level (less than 10 TU). There was no correlation between the tritium concentration and the chemical composition of the rainwater. The tritium levels obtained from this study could be used as a basis for reference and monitoring of future environmental changes due to nuclear accidents or activities, both domestically and internationally.
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Affiliation(s)
- Kanokwan Khamanek
- Department of Applied Radiation and Isotopes, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand
| | - Soontree Khuntong
- Faculty of Science at Sriracha, Kasetsart University, Sriracha, Cholburi, 20230, Thailand
| | - Kiadtisak Saenboonruang
- Department of Applied Radiation and Isotopes, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand
| | - Donruedee Toyen
- Department of Materials Science, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand
| | - Chittranuch Chantarot
- Department of Applied Radiation and Isotopes, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand
| | - Monthon Yongprawat
- Nuclear Technology Research and Development Center, Thailand Institute of Nuclear Technology (Public Organization), Nakhon Nayok, 26120, Thailand
| | - Chakrit Saengkorakot
- Nuclear Technology Research and Development Center, Thailand Institute of Nuclear Technology (Public Organization), Nakhon Nayok, 26120, Thailand
| | - Archara Phattanasub
- Radioactive Waste Management Center, Thailand Institute of Nuclear Technology (Public Organization), Nakhon Nayok, 26120, Thailand
| | | | - Ryuta Hazama
- Graduate School of Human Environment, Osaka Sangyo University, Osaka, 574-8530, Japan
| | - Anawat Rittirong
- Research Center for Nuclear Physics, Osaka University, Osaka, 574-8530, Japan
| | - Wanwisa Sudprasert
- Department of Applied Radiation and Isotopes, Faculty of Science, Kasetsart University, Bangkok, 10900, Thailand.
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3
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Morereau A, Lepage H, Claval D, Cossonnet C, Ambrosi JP, Mourier B, Winiarski T, Copard Y, Eyrolle F. Trajectories of technogenic tritium in the Rhône River (France). JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 223-224:106370. [PMID: 32883536 DOI: 10.1016/j.jenvrad.2020.106370] [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: 04/17/2020] [Revised: 07/22/2020] [Accepted: 07/23/2020] [Indexed: 06/11/2023]
Abstract
Tritium is a radioisotope of hydrogen with a half-life of 12.32 years and was used for its luminescent properties by the watchmaking industry from 1962 to the 2008. Tritiated luminescent salts were integrated in the paints applied on the index and dial of watches and clocks. French and Swiss watchmaking workshops used more than 28 000 TBq of tritium over this period of time and produced almost 350 million watches. Despite the end of tritiated salts use in watchmaking workshops in 1992 in France and 2008 in Switzerland, high level of organically bound tritium (OBT) are still observed in sediments of the Rhône River downstream the Lake Geneva. Contamination of the Rhône River by tritiated hot particles since 1962 up to nowadays remains poorly documented. In order to assess the long term behavior and fate of technogenic tritium in this river and its trajectories in the river system, two sediment cores were collected at the upstream (UC) and downstream (DC) part of the Rhône River in France and OBT contents were determined. For both sedimentary cores, maximum OBT contents were registered over the 1980s when tritium was intensively used by watchmaking industries. These residual OBT contents are 1 000 to 10 000 fold higher than current natural background levels in riverine sediments. The OBT contents progressively decreased since 1989 with close effective half-life in upstream and downstream area (5 ± 2 years). The OBT contents were lower in DC than in UC due to the dilution by uncontaminated sediments delivered by tributaries not affected by the watchmaking industries. Trajectories analysis indicates that the resiliency of the Rhône River system in regards to this contamination would be reached in 14-70 years and in 14-28 years respectively for the upstream and downstream part of the river.
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Affiliation(s)
- A Morereau
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SRTE/LRTA PSE-ENV/SEREN/LEREN PSE-ENV/SAME/LMRE, BP 3, 13115, Saint-Paul-lez-Durance, France.
| | - H Lepage
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SRTE/LRTA PSE-ENV/SEREN/LEREN PSE-ENV/SAME/LMRE, BP 3, 13115, Saint-Paul-lez-Durance, France
| | - D Claval
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SRTE/LRTA PSE-ENV/SEREN/LEREN PSE-ENV/SAME/LMRE, BP 3, 13115, Saint-Paul-lez-Durance, France
| | - C Cossonnet
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SRTE/LRTA PSE-ENV/SEREN/LEREN PSE-ENV/SAME/LMRE, BP 3, 13115, Saint-Paul-lez-Durance, France
| | - J P Ambrosi
- Aix-Marseille Université, CNRS, IRD, INRA, Coll France, CEREGE, Aix-en-Provence, France
| | - B Mourier
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69518, Vaulx-en-Velin, France
| | - T Winiarski
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS, ENTPE, UMR5023 LEHNA, F-69518, Vaulx-en-Velin, France
| | - Y Copard
- Normandie Univ Rouen, UNIROUEN, UNICAEN, CNRS, M2C, 76000, Rouen, France
| | - F Eyrolle
- Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSE-ENV/SRTE/LRTA PSE-ENV/SEREN/LEREN PSE-ENV/SAME/LMRE, BP 3, 13115, Saint-Paul-lez-Durance, France
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Rashmi NS, D'Souza RS, Kamath SS, Mohan MP, Bharath S, Narayana B, Ravi PM, Karunakara N. Experimental database on water equivalent factor (WEQ p) and organically bound tritium activity for tropical monsoonal climate region of South West Coast of India. Appl Radiat Isot 2020; 166:109390. [PMID: 33091858 DOI: 10.1016/j.apradiso.2020.109390] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/31/2020] [Accepted: 08/18/2020] [Indexed: 10/23/2022]
Abstract
Tritium in the form of tritiated water is easily incorporated into terrestrial biota as tissue free water tritium (TFWT). A part of TFWT is converted into organically bound tritium (OBT) through metabolic processes. For the computation of NE-OBT activity (expressed as Bq L-1 of combustion water) in terrestrial plants, knowledge on 'water equivalent factor (WEQp)', defined as the volume of water produced from the combustion of 1 kg of the dry sample, is essential. On a global scenario, experimental data are not available on this parameter. This paper presents (i) a method for determination of WEQp by combustion method using a tube furnace system, (ii) a large database (N = 294) on WEQp parameter for samples of tropical monsoonal climate region of the Indian subcontinent, and (iii) NE-OBT activity in terrestrial biota samples (N = 186) collected from the vicinity of a PHWR nuclear power plant of India. The data generated in this study on WEQp serves for the validation of the data compiled in IAEA (2009 and 2010), which are estimated based on the hydrogen content of protein, fat and carbohydrates, and the fractions of protein, fat and carbohydrates. The WEQp varied in the ranges of 0.492-0.678 L kg-1 (GM = 0.569 Bq L-1, GSD = 1.06), 0.520-0.630 L kg-1 (GM = 0.557 Bq L-1, GSD = 1.02) 0.473-0.633 L kg-1 (GM = 0.562 Bq L-1, GSD = 1.02) for non-leafy vegetables, leafy vegetables, and fruits, respectively. A comparison between the experimental WEQp data with those compiled in the IAEA report revealed that the maximum deviation between the two data sets is <10%. The NE-OBT activity in the food samples collected from 2.3 to 20 km zone around NPP had a geometric mean (GM) value of 25.4 Bq L-1 (GSD = 1.6, N = 186). Variations in NE-OBT activity with different seasons of the year are discussed.
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Affiliation(s)
- Nayak S Rashmi
- Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, Mangalagangothri, 574199, India
| | - Renita Shiny D'Souza
- Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, Mangalagangothri, 574199, India
| | - Srinivas S Kamath
- Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, Mangalagangothri, 574199, India
| | - M P Mohan
- Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, Mangalagangothri, 574199, India
| | - S Bharath
- Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, Mangalagangothri, 574199, India
| | - B Narayana
- Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, Mangalagangothri, 574199, India
| | - P M Ravi
- Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, Mangalagangothri, 574199, India
| | - N Karunakara
- Centre for Advanced Research in Environmental Radioactivity (CARER), Mangalore University, Mangalagangothri, 574199, India.
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Barisevičiūtė R, Maceika E, Ežerinskis Ž, Šapolaitė J, Butkus L, Mažeika J, Rakauskas V, Juodis L, Steponėnas A, Druteikienė R, Remeikis V. Distribution of radiocarbon in sediments of the cooling pond of RBMK type Ignalina Nuclear Power Plant in Lithuania. PLoS One 2020; 15:e0237605. [PMID: 32804934 PMCID: PMC7430730 DOI: 10.1371/journal.pone.0237605] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 07/29/2020] [Indexed: 11/18/2022] Open
Abstract
The vertical distribution of radiocarbon (14C) was examined in the bottom sediment core, taken from Lake Drūkšiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for"Channelized Large Power Reactor"). 14C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210Pb and 137Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947-2013 period. In addition, 14C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947-1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14C specific activity in both fractions increased by 11.4-13.6 pMC during the first 15 years of plant operation. However, during the 2000-2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14C contained in liquid effluences from the INPP in 2000-2009. The discrepancy between 14C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment.
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Affiliation(s)
- Rūta Barisevičiūtė
- State Research Institute Center for Physical Sciences and Technology, Vilnius, Lithuania
- * E-mail:
| | - Evaldas Maceika
- State Research Institute Center for Physical Sciences and Technology, Vilnius, Lithuania
| | - Žilvinas Ežerinskis
- State Research Institute Center for Physical Sciences and Technology, Vilnius, Lithuania
| | - Justina Šapolaitė
- State Research Institute Center for Physical Sciences and Technology, Vilnius, Lithuania
| | - Laurynas Butkus
- State Research Institute Center for Physical Sciences and Technology, Vilnius, Lithuania
| | - Jonas Mažeika
- State Research Institute Nature Research Centre, Vilnius, Lithuania
| | | | - Laurynas Juodis
- State Research Institute Center for Physical Sciences and Technology, Vilnius, Lithuania
| | | | - Rūta Druteikienė
- State Research Institute Center for Physical Sciences and Technology, Vilnius, Lithuania
| | - Vidmantas Remeikis
- State Research Institute Center for Physical Sciences and Technology, Vilnius, Lithuania
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Lepage H, Eyrolle F, Ducros L, Claval D. Spatial and temporal variation of tritium concentrations during a dam flushing operation. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 218:106261. [PMID: 32421581 DOI: 10.1016/j.jenvrad.2020.106261] [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: 01/29/2020] [Revised: 02/28/2020] [Accepted: 03/19/2020] [Indexed: 06/11/2023]
Abstract
Tritium is a radionuclide commonly observed worldwide in riverine systems. In the Rhône River downstream the Lake Geneva (Switzerland and France), its occurrence is also related to its use for its luminescent properties in watchmaking paints. In fact, tritium is regularly observed at anomalous levels in this river and extreme events such as flushing operations might conduct to its transport downstream. In the Rhône River, characterized by 21 dams downstream the Geneva Lake, such operations are regularly organized to remove the sediments and limit problematic consequences such as siltation and increased flooding hazards. The consequences of dam flushing operations on tritium concentrations were thus investigated. Samples of Suspended Particulate Matter (SPM) and water were collected in the Rhone River downstream of Geneva in June 2012, during a planned flushing operation of three upstream reservoirs (Verbois, Chancy-Pougny and Génissiat). The concentrations of tritiated water (HTO) and organically bound Tritium (OBT) were measured and compared to reference concentrations. The flushing operations had no impact on the HTO concentration while the increases observed were related to the authorized releases of HTO from a nuclear power plant located downstream the dams. High increases of OBT concentrations in SPM were observed at two stations (Creys-Malville and Jons) without clear spatial or temporal trends. These anomalous peaks could be explained by the heterogeneous spatial distribution of technogenic tritium leading to large variations of tritium concentrations within the samples even though collected in areas close to each other. The results highlight the need to investigate the amount of such technogenic tritium currently stored in the upstream Rhone River as it might be significant.
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Affiliation(s)
- Hugo Lepage
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, BP 3, 13115, Saint-Paul-lez-Durance, France.
| | - Frédérique Eyrolle
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, BP 3, 13115, Saint-Paul-lez-Durance, France
| | - Loïc Ducros
- Université de Nîmes, EA7352 CHROME, Laboratoire GIS, Parc scientifique et technique G. Besse, 150 rue Georges Besse, 30000, Nîmes, France
| | - David Claval
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, BP 3, 13115, Saint-Paul-lez-Durance, France
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Eyrolle F, Lepage H, Antonelli C, Morereau A, Cossonnet C, Boyer P, Gurriaran R. Radionuclides in waters and suspended sediments in the Rhone River (France) - Current contents, anthropic pressures and trajectories. THE SCIENCE OF THE TOTAL ENVIRONMENT 2020; 723:137873. [PMID: 32392680 DOI: 10.1016/j.scitotenv.2020.137873] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 03/09/2020] [Accepted: 03/10/2020] [Indexed: 06/11/2023]
Abstract
The Rhone River is one of the most nuclearized river in the world. Radionuclide concentrations in water and suspended sediments transferred to the marine environment were intensively monitored in this river over the last decades (2002-2018). Over this period of time, >12 and 25 time integrating samples were collected each year in filtered waters and suspended sediments, respectively, and analyzed for their radionuclide contents at ultra-trace levels by using top performance analytical tools. While >60% of plutonium, americium, cesium, cobalt, silver, beryllium and actinium radioisotopes are carried by sedimentary particles, sodium, tritium, antimony and strontium are mainly exported as dissolved species (>90%) due to their low affinity with particles. Most natural radionuclides contents show low seasonal variation. No significant trends are observed over the last two decades for these elements, even for 40K widely used in fertilizers after the middle of the last century, indicating that the basin has currently converged towards geochemical equilibrium for all of them. In contrast, the concentrations of numerous anthropogenic radionuclides originating from nuclear industries significantly declined since the beginning of the 2000s. Assuming no change of the current anthropic and climatic pressures over the next decades, apparent periods, i.e. the time required for a reduction by half the concentrations in the downstream part of the Rhône River, would be close to 6 years for most artificial radionuclides, except for tritium and other artificial radionuclides conveyed to the river by soil leaching and erosion (90Sr, 241Am, plutonium isotopes) which would be far longer. Referring to regional referential backgrounds, only few anthropogenic radionuclides specifically produced by nuclear industries are still detectable at the downstream part of the Rhone River and excess contents of tritium, 238Pu and 241Am are observed in filtered waters.
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Affiliation(s)
- Frédérique Eyrolle
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France.
| | - Hugo Lepage
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Christelle Antonelli
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Amandine Morereau
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Catherine Cossonnet
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Patrick Boyer
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Rodolfo Gurriaran
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
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8
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Kim SB, Bredlaw M, Rousselle H, Stuart M. Distribution of organically bound tritium (OBT) activity concentrations in aquatic biota from eastern Canada. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 208-209:105997. [PMID: 31229735 DOI: 10.1016/j.jenvrad.2019.105997] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/30/2019] [Accepted: 06/17/2019] [Indexed: 06/09/2023]
Abstract
A survey of eastern Canadian biota was conducted to determine the distribution of activity concentrations of organically bound tritium (OBT). Fish samples were collected from Lake Ontario and the St. Lawrence River in areas continuously receiving inputs of tritiated water (HTO) from operating nuclear power plants, and from Lake Nipissing, a background area. Components of their aquatic environments were sampled. The data collected also provides some insight on how tritium activity concentrations in ambient water influence tissue free water tritium (TFWT) and OBT activity concentrations in biological tissues. Using an ALOKA liquid scintillation system, fish TFWT and OBT were quantified. Fish TFWT averaged 1.6 ± 0.1 Bq/L in Lake Nipissing and 3.1 ± 0.3 Bq/L in Lake Ontario. In contrast, TFWT ranged from 11.1 to 80.8 Bq/L in the St. Lawrence River near the Gentilly-2 Canada Deuterium Uranium (CANDU) site. Fish tissue OBT levels were 4.0 ± 0.4 Bq/L and 5.3 ± 0.2 Bq/L for Lake Nipissing and Lake Ontario, respectively, and between 18.1 and 134.2 Bq/L for CANDU sites. The activity concentrations of TFWT and OBT were reviewed for algae, freshwater mussel and various fish samples collected near Gentilly-2, Pickering and Darlington Nuclear Power Generating Stations. TFWT in aquatic biota was found to correlate with the tritium activity concentrations measured in waters at the time of sampling (TFWT/HTO of ambient water was 0.3-4.3). The OBT concentration factors (OBT/HTO of ambient water) were found to be higher in freshwater mussels (between 17 and 47) compared to algae and fish (0.3-10). These results point to a heterogeneous distribution of biota OBT content in these aquatic ecosystems. It was also noted that all fish and algae samples were found to be within the range of tritium activity concentrations that has been historically measured in the same waters. Values in freshwater mussels were above this range.
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Affiliation(s)
- S B Kim
- Environmental Sciences Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada.
| | - M Bredlaw
- Environmental Sciences Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
| | - H Rousselle
- Environmental Sciences Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
| | - M Stuart
- Environmental Sciences Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
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Kim SB, Bredlaw M, Rousselle H, Farrow F, Carr J, Korolevych VY, Stuart M. Organically bound tritium (OBT) activity concentrations in surface soil at the Chalk River Laboratories, Canada. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 208-209:105999. [PMID: 31271849 DOI: 10.1016/j.jenvrad.2019.105999] [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: 04/04/2019] [Revised: 06/11/2019] [Accepted: 06/23/2019] [Indexed: 06/09/2023]
Abstract
Canadian Nuclear Laboratories (CNL)'s Chalk River Laboratories (CRL) site is home to a large nuclear research complex in Canada. CRL's air tritium releases amount to about 1015 Bq/year. The objective of the study was to characterize the spatial footprint of the 60 years of tritium atmospheric releases in surface soil by measurement of organically bound tritium (OBT). Soil OBT activity concentrations were of particular interest because soil represents a long-term tritium reservoir that can act as a historical record of tritium releases into the environment. Soil samples to a 5 cm depth were collected within the CRL site from 2012 to 2014. Each sample was analyzed for tritiated water (HTO) and OBT activity concentrations. The highest HTO and OBT measurements obtained during this study were 154.0 ± 7.8 Bq/L and 180.9 ± 37.3 Bq/L, respectively. A developed OBT map indicated that retained tritium in soil was not related to the distance of sources-term but it was related to the prevailing wind direction.
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Affiliation(s)
- S B Kim
- Environmental Sciences Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada.
| | - M Bredlaw
- Environmental Sciences Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
| | - H Rousselle
- Environmental Sciences Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
| | - F Farrow
- Environmental Sciences Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
| | - J Carr
- Environmental Sciences Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
| | - V Y Korolevych
- Environmental Sciences Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
| | - M Stuart
- Environmental Sciences Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
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10
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Beaton ED, Gosselin I, Festarini A, Gagnaire B, Farrow F, Cavalié I, Shultz C, Kim SB, Walsh S, Chen HQ, Adam-Guillermin C, Stuart M. Correlated responses for DNA damage, phagocytosis activity and lysosomal function revealed in a comparison between field and laboratory studies: Fathead minnow exposed to tritium. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 662:990-1002. [PMID: 30795485 DOI: 10.1016/j.scitotenv.2019.01.261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 01/08/2019] [Accepted: 01/17/2019] [Indexed: 06/09/2023]
Abstract
Tritium entering the aquatic environment can confer a whole body internal radiological dose to aquatic organisms. Multiple stressors inherent in natural environments, however, confound estimates for observable radiation specific responses. To disentangle differences between field and laboratory outcomes to tritium exposures, a multivariate analysis comparing biomarkers for radiation exposure at the cellular level with changes in biological processes within tissues is described for fathead minnows (Pimephales promelas). Over tritium activity concentrations up to 180,000 Bq/L, DNA damage in the field were lower than DNA damage in the laboratory. This finding does not support an increase in morbidity of biota in field exposures. Energy deposited by tritium decay produces oxidised free radicals, yet the biological responses in brain, muscle and liver to oxidative stress differed between the studies and were not related to the tritium. For both studies, DNA damage in gonad and blood increased with increased tritium as did the fluorescence associated with lysosomal function in spleen. The studies differed in spleen phagocytosis activity were, in the laboratory but not the field, activity increased with increased tritium-and was correlatd with lysosomal function (Spearman coefficient of 0.98 (p = 0.001). The higher phagocytosis activity in the field reflects exposures to unmeasured factors that were not present within the laboratory. In the laboratory, DNA damage and lysosomal function were correlated: Spearman coefficients of 0.9 (Comet, p = 0.03) and 0.9 (micronuclei, p = 0.08). In the field, DNA damage by the Comet assay, but not by micronucleus frequency, correlated with lysosomal function: Spearman coefficients of 0.91 (Comet, p < 0.001) and 0.47 (micronuclei, p = 0.21). These observations highlight a need for better physiologic understanding of linkages between radiation-induced damage within cells and responses at higher levels of biological organization.
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Affiliation(s)
- E D Beaton
- Canadian Nuclear Laboratories (formerly Atomic Energy of Canada Limited), Chalk River Laboratories, 286 Plant Road, Chalk River, ON K0J 1J0, Canada.
| | - Isabelle Gosselin
- Canadian Nuclear Laboratories (formerly Atomic Energy of Canada Limited), Chalk River Laboratories, 286 Plant Road, Chalk River, ON K0J 1J0, Canada
| | - Amy Festarini
- Canadian Nuclear Laboratories (formerly Atomic Energy of Canada Limited), Chalk River Laboratories, 286 Plant Road, Chalk River, ON K0J 1J0, Canada
| | - Beatrice Gagnaire
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV/SRTE/LECO, Cadarache, Saint-Paul-lez-Durance 13115, France
| | - Francesca Farrow
- Canadian Nuclear Laboratories (formerly Atomic Energy of Canada Limited), Chalk River Laboratories, 286 Plant Road, Chalk River, ON K0J 1J0, Canada
| | - Isabelle Cavalié
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV/SRTE/LECO, Cadarache, Saint-Paul-lez-Durance 13115, France
| | - Carmen Shultz
- Canadian Nuclear Laboratories (formerly Atomic Energy of Canada Limited), Chalk River Laboratories, 286 Plant Road, Chalk River, ON K0J 1J0, Canada
| | - Sang Bog Kim
- Canadian Nuclear Laboratories (formerly Atomic Energy of Canada Limited), Chalk River Laboratories, 286 Plant Road, Chalk River, ON K0J 1J0, Canada
| | - Stephanie Walsh
- Canadian Nuclear Laboratories (formerly Atomic Energy of Canada Limited), Chalk River Laboratories, 286 Plant Road, Chalk River, ON K0J 1J0, Canada
| | - Hui Qun Chen
- Canadian Nuclear Laboratories (formerly Atomic Energy of Canada Limited), Chalk River Laboratories, 286 Plant Road, Chalk River, ON K0J 1J0, Canada
| | - Christelle Adam-Guillermin
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV/SRTE/LECO, Cadarache, Saint-Paul-lez-Durance 13115, France
| | - Marilyne Stuart
- Canadian Nuclear Laboratories (formerly Atomic Energy of Canada Limited), Chalk River Laboratories, 286 Plant Road, Chalk River, ON K0J 1J0, Canada
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Eyrolle F, Lepage H, Copard Y, Ducros L, Claval D, Saey L, Cossonnet C, Giner F, Mourier D. A brief history of origins and contents of Organically Bound Tritium (OBT) and 14C in the sediments of the Rhône watershed. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 643:40-51. [PMID: 29935362 DOI: 10.1016/j.scitotenv.2018.06.074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Revised: 06/06/2018] [Accepted: 06/07/2018] [Indexed: 06/08/2023]
Abstract
Tritium (3H) and Carbon-14 (14C) are radionuclides of natural (cosmogenic) origin that have also been introduced into the environment by humans since the middle of the last century. They are therefore not compounds that have only recently been released into the environment and they do not pose a recognized health threat due to their low radiotoxicity. However, they hold an important place among current concerns because they are being discharged into the environment by the nuclear industry in large quantities compared to other radionuclides. Those both radionuclides partly integrate organic matter during metabolic processes (i.e., photosynthesis) leading to organically bound forms that can be found in sediments. Organically bound tritium (OBT) analyses carried out on the sediments of the Rhône and its tributaries indicate a significant and historical tritium labelling of sedimentary particles all along the Rhône river, as well as in several northern tributaries, in particular the Ognon and the Tille rivers (tributaries of the Saone), the Doubs River and the Loue River (a tributary of the Doubs) and the Arve river. The recorded levels (10 to over 20,000 Bq/L) are very likely to be related to the presence of synthetic tritiated particles (technogenic tritium), which were used in the past in watchmaking workshops. Although overall contamination levels decrease from north to south in the Rhône watershed and fade over time, particularly due to the radioactive decay of tritium, this contamination source of technogenic tritium in the Rhône watersheds is currently still not negligible. Carbon-14 analyses show that the Rhône sediments generally display 14C levels close to the atmospheric reference values (231 Bq·kg-1 of C in 2015) or even lower in most of cases, and show sporadic and weak labelling near nuclear facilities. The low 14C levels in the Rhône sediments are most likely related to the solid contributions from tributaries draining areas that are rich in fossil organic matter, and therefore devoid of 14C. In the Rhône watershed, the presence in solid particles of tritium in a form organically bound to synthetic compounds and of petrogenic (fossil) organic carbon, can potentially alter the apparent assimilation rates to the food chain of these two radionuclides.
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Affiliation(s)
- Frédérique Eyrolle
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France.
| | - Hugo Lepage
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Yoann Copard
- University of Rouen-Normandie, UMR CNRS 6143 M2C, 76821 Mont Saint Aignan, France
| | - Loic Ducros
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - David Claval
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Lionel Saey
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Catherine Cossonnet
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Franck Giner
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - David Mourier
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE/LRTA, SEREN/LEREN, SAME/LMRE, BP 3, 13115 Saint-Paul-lez-Durance, France
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12
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Eyrolle F, Ducros L, Le Dizès S, Beaugelin-Seiller K, Charmasson S, Boyer P, Cossonnet C. An updated review on tritium in the environment. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 181:128-137. [PMID: 29149670 DOI: 10.1016/j.jenvrad.2017.11.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 10/31/2017] [Accepted: 11/01/2017] [Indexed: 06/07/2023]
Abstract
Various studies indicated more or less recently that organically bound tritium (OBT) formed from gaseous or liquid tritium releases into the environment potentially accumulates in organisms contradicting hypotheses associated to methods used to assess the biological impact of tritium on humans (ASN, 2010). Increasing research works were then performed during the last decade in order to gain knowledge on this radionuclide expected to be increasingly released by nuclear installations in the near future within the environment. This review focusses on publications of the last decade. New unpublished observations revealing the presence of technogenic tritium in a sedimentary archive collected in the upper reaches of the Rhône river and findings from the Northwestern Mediterranean revealing in all likelihood the impact of terrigenous tritium inputs on OBT levels recorded in living organisms are also presented. Identifying and understanding the physicochemical forms of tritium and the processes leading to its persistence in environmental compartments would explain most observations regarding OBT concentrations in organisms and definitively excludes that tritium would "bio accumulate" within living organisms.
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Affiliation(s)
- Frédérique Eyrolle
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE, BP 3, 13115 Saint-Paul-lez-Durance, France.
| | - Loïc Ducros
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Séverine Le Dizès
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Karine Beaugelin-Seiller
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Sabine Charmasson
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Patrick Boyer
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SRTE, BP 3, 13115 Saint-Paul-lez-Durance, France
| | - Catherine Cossonnet
- Institut de Radioprotection et de Sureté Nucléaire (IRSN), PSE-ENV, SAME, Bois des Rames, Bat 501, 91400 Orsay, France
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Kim SB, Farrow F, Bredlaw M, Stuart M. Changes in HTO and OBT activity concentrations in the Perch Lake aquatic ecosystem. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 165:280-285. [PMID: 27816047 DOI: 10.1016/j.jenvrad.2016.10.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Revised: 10/21/2016] [Accepted: 10/26/2016] [Indexed: 06/06/2023]
Abstract
Perch Lake, a small shallow shield lake located on the Chalk River Laboratories (CRL) site, contains elevated levels of tritium due to inputs from a nearby nuclear waste management area. The releases have been going on for many years but tritium levels in Perch Lake have been gradually decreasing since about year 2000. Lake water, sediments, aquatic plants, clams and fish were collected during the summer and fall of 2003 and 2013 at three locations in the lake. HTO activity concentrations were measured in all samples and OBT activity concentrations were measured in sediments, plants, clams and fish. In 2003, 2013, HTO activity concentrations in lake water were roughly uniform in time and space, except close to the shoreline where concentrations were fluctuating according to stream water and groundwater tritium levels in streams entering the lake. HTO activity concentrations of biota were similar to concentrations in lake water at the site where they were collected. OBT activity concentrations in biota were not always correlating with the lake water HTO levels. OBT to HTO ratios were found to be less than 1 for aquatic plants, around 1 for clams and fish and above 1 for birds reared on the shore of the lake.
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Affiliation(s)
- S B Kim
- Environmental Technologies Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada.
| | - F Farrow
- Environmental Technologies Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
| | - M Bredlaw
- Environmental Technologies Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
| | - M Stuart
- Environmental Technologies Branch, Canadian Nuclear Laboratories, Chalk River, Ontario, K0J 1J0, Canada
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14
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Method for organically bound tritium analysis from sediment using a combustion bomb. Appl Radiat Isot 2016; 118:136-139. [PMID: 27640174 DOI: 10.1016/j.apradiso.2016.09.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 08/23/2016] [Accepted: 09/08/2016] [Indexed: 11/22/2022]
Abstract
The method consisted in combustion, using a Parr bomb type 1121, of a sediment - tritium free promoter mixture. The proper ratio sediment to promoter in our experiments was between 1:3 and 1:2, higher ratio resulting in unreliable results, due to incomplete combustion of the sample. The described method was used to measure the estuarine sediment sample from the 2nd International OBT Intercomparison Exercise, the average reported value being 163±12Bqkg-1 dry matter (k=2).
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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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