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Cynthia K. Russel - One of the best experts on this subject based on the ideXlab platform.
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assessment of Radium 226 bioavailability and bioaccumulation downstream of decommissioned uranium operations using the caged oligochaete lumbriculus variegatus
Environmental Toxicology and Chemistry, 2015Co-Authors: Cheryl I. E. Wiramanaden, Patricia L. Orr, Cynthia K. RusselAbstract:The present study investigated the integrated effects of several geochemical processes that control Radium-226 ((226) Ra) mobility in the aquatic environment and bioaccumulation in in situ caged benthic invertebrates. Radium-226 bioaccumulation from sediment and water was evaluated using caged oligochaetes (Lumbriculus variegatus) deployed for 10 d in 6 areas downstream of decommissioned uranium operations in Ontario and Saskatchewan, Canada. Measured (226) Ra radioactivity levels in the retrieved oligochaetes did not relate directly to water and sediment exposure levels. Other environmental factors that may influence (226) Ra bioavailability in sediment and water were investigated. The strongest mitigating influence on (226) Ra bioaccumulation factors was sediment barium concentration, with elevated barium (Ba) levels being related to use of barium chloride in effluent treatment for removing (226) Ra through barite formation. Observations from the present study also indicated that (226) Ra bioavailability was influenced by dissolved organic carbon in water, and by gypsum, carbonate minerals, and iron oxyhydroxides in sediment, suggestive of sorption processes. Environmental factors that appeared to increase (226) Ra bioaccumulation were the presence of other group (II) ions in water (likely competing for binding sites on organic carbon molecules), and the presence of K-feldspars in sediment, which likely act as a dynamic repository for (226) Ra where weak ion exchange can occur. In addition to influencing bioavailability to sediment biota, secondary minerals such as gypsum, carbonate minerals, and iron oxyhydroxides likely help mitigate (226) Ra release into overlying water after the dissolution of sedimentary barite. Environ Toxicol Chem 2015;34:507-517. © 2014 SETAC.
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Assessment of Radium‐226 bioavailability and bioaccumulation downstream of decommissioned uranium operations, using the caged oligochaete (Lumbriculus variegatus)
Environmental Toxicology and Chemistry, 2015Co-Authors: Cheryl I. E. Wiramanaden, Patricia L. Orr, Cynthia K. RusselAbstract:The present study investigated the integrated effects of several geochemical processes that control Radium-226 ((226) Ra) mobility in the aquatic environment and bioaccumulation in in situ caged benthic invertebrates. Radium-226 bioaccumulation from sediment and water was evaluated using caged oligochaetes (Lumbriculus variegatus) deployed for 10 d in 6 areas downstream of decommissioned uranium operations in Ontario and Saskatchewan, Canada. Measured (226) Ra radioactivity levels in the retrieved oligochaetes did not relate directly to water and sediment exposure levels. Other environmental factors that may influence (226) Ra bioavailability in sediment and water were investigated. The strongest mitigating influence on (226) Ra bioaccumulation factors was sediment barium concentration, with elevated barium (Ba) levels being related to use of barium chloride in effluent treatment for removing (226) Ra through barite formation. Observations from the present study also indicated that (226) Ra bioavailability was influenced by dissolved organic carbon in water, and by gypsum, carbonate minerals, and iron oxyhydroxides in sediment, suggestive of sorption processes. Environmental factors that appeared to increase (226) Ra bioaccumulation were the presence of other group (II) ions in water (likely competing for binding sites on organic carbon molecules), and the presence of K-feldspars in sediment, which likely act as a dynamic repository for (226) Ra where weak ion exchange can occur. In addition to influencing bioavailability to sediment biota, secondary minerals such as gypsum, carbonate minerals, and iron oxyhydroxides likely help mitigate (226) Ra release into overlying water after the dissolution of sedimentary barite. Environ Toxicol Chem 2015;34:507-517. © 2014 SETAC.
Katell Morvan - One of the best experts on this subject based on the ideXlab platform.
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Determination of Radium-226 in Aqueous Solutions by α-Spectrometry
Analytical Chemistry, 2001Co-Authors: Katell Morvan, Yves Andres, Bandombele Mokili, Jean-charles AbbeAbstract:The new European legislation imposes a lower threshold for radioactivity in drinking water. This requires the development of more sensitive and reliable analytical methods. This work presents an improved α-spectrometric technique to determine the Radium-226 activity in aqueous solution relying on the Radium adsorption onto a thin manganese oxide layer followed by α-measurement. The preparation of the MnO2 deposit has been optimized as well as the Radium adsorption conditions. Detection threshold and limit of 5 and 10 mBq·L-1, respectively, with a 10% (95% confidence) uncertainty are currently reached. This paper reports on the overall technique and on its application to assess the Radium-226 activity in 28 French mineral waters. In addition, the gross α- and β-activities have been evaluated using proportional counting while the uranium concentrations were derived from ICPMS.
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Determination of Radium-226 in aqueous solutions by alpha-spectrometry
Analytical Chemistry, 2001Co-Authors: Katell Morvan, Yves Andres, Bandombele Mokili, Jc. AbbeAbstract:The new European legislation imposes a lower threshold for radioactivity in drinking water.. This requires the development of more sensitive and reliable analytical methods. This work presents an improved a-spectrometric technique to determine the Radium-226 activity in aqueous solution relying on the Radium adsorption onto a thin manganese oxide layer followed by a-measurement. The preparation of the MnO2 deposit has been optimized as well as the Radium adsorption conditions. Detection threshold and limit of 5 and 10 mBq .L-1, respectively, with a 10% (95% confidence) uncertainty are currently reached. This paper reports on the overall technique and on its application to assess the Radium-226 activity in 28 French mineral waters. In addition, the gross alpha- and beta -activities have been evaluated using proportional counting while the uranium concentrations were derived from ICPMS.
Jc. Abbe - One of the best experts on this subject based on the ideXlab platform.
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Determination of Radium-226 in aqueous solutions by alpha-spectrometry
Analytical Chemistry, 2001Co-Authors: Katell Morvan, Yves Andres, Bandombele Mokili, Jc. AbbeAbstract:The new European legislation imposes a lower threshold for radioactivity in drinking water.. This requires the development of more sensitive and reliable analytical methods. This work presents an improved a-spectrometric technique to determine the Radium-226 activity in aqueous solution relying on the Radium adsorption onto a thin manganese oxide layer followed by a-measurement. The preparation of the MnO2 deposit has been optimized as well as the Radium adsorption conditions. Detection threshold and limit of 5 and 10 mBq .L-1, respectively, with a 10% (95% confidence) uncertainty are currently reached. This paper reports on the overall technique and on its application to assess the Radium-226 activity in 28 French mineral waters. In addition, the gross alpha- and beta -activities have been evaluated using proportional counting while the uranium concentrations were derived from ICPMS.
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Measurement of Radium-226 by alpha spectrometry
2000Co-Authors: K. Morvan, Yves Andres, Mb. Mokili, Jc. AbbeAbstract:La methode d'analyse du Radium-226 par spectrometrie alpha, mise au point au laboratoire Subatech (Nantes), offre une alternative aux autres techniques deja existantes. Elle est basee sur la capacite du dioxyde de manganese hydrate a adsorber le Radium de maniere selective. La technique proposee s'articule autour de deux etapes : (1) la preparation des couches minces de MnO 2 et (2) l'adsorption du Radium-226 sur cet oxyde metallique. Les parametres d'adsorption ainsi que les caracteristiques analytiques de la methode ont ete etudies. De plus, la teneur en 226 Ra de quelques eaux minerales a ete mesuree. Cette technique de dosage permet l'analyse aisee et rapide par spectrometrie alpha, en solution aqueuse, du Radium-226 a de faibles activites.
Cheryl I. E. Wiramanaden - One of the best experts on this subject based on the ideXlab platform.
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assessment of Radium 226 bioavailability and bioaccumulation downstream of decommissioned uranium operations using the caged oligochaete lumbriculus variegatus
Environmental Toxicology and Chemistry, 2015Co-Authors: Cheryl I. E. Wiramanaden, Patricia L. Orr, Cynthia K. RusselAbstract:The present study investigated the integrated effects of several geochemical processes that control Radium-226 ((226) Ra) mobility in the aquatic environment and bioaccumulation in in situ caged benthic invertebrates. Radium-226 bioaccumulation from sediment and water was evaluated using caged oligochaetes (Lumbriculus variegatus) deployed for 10 d in 6 areas downstream of decommissioned uranium operations in Ontario and Saskatchewan, Canada. Measured (226) Ra radioactivity levels in the retrieved oligochaetes did not relate directly to water and sediment exposure levels. Other environmental factors that may influence (226) Ra bioavailability in sediment and water were investigated. The strongest mitigating influence on (226) Ra bioaccumulation factors was sediment barium concentration, with elevated barium (Ba) levels being related to use of barium chloride in effluent treatment for removing (226) Ra through barite formation. Observations from the present study also indicated that (226) Ra bioavailability was influenced by dissolved organic carbon in water, and by gypsum, carbonate minerals, and iron oxyhydroxides in sediment, suggestive of sorption processes. Environmental factors that appeared to increase (226) Ra bioaccumulation were the presence of other group (II) ions in water (likely competing for binding sites on organic carbon molecules), and the presence of K-feldspars in sediment, which likely act as a dynamic repository for (226) Ra where weak ion exchange can occur. In addition to influencing bioavailability to sediment biota, secondary minerals such as gypsum, carbonate minerals, and iron oxyhydroxides likely help mitigate (226) Ra release into overlying water after the dissolution of sedimentary barite. Environ Toxicol Chem 2015;34:507-517. © 2014 SETAC.
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Assessment of Radium‐226 bioavailability and bioaccumulation downstream of decommissioned uranium operations, using the caged oligochaete (Lumbriculus variegatus)
Environmental Toxicology and Chemistry, 2015Co-Authors: Cheryl I. E. Wiramanaden, Patricia L. Orr, Cynthia K. RusselAbstract:The present study investigated the integrated effects of several geochemical processes that control Radium-226 ((226) Ra) mobility in the aquatic environment and bioaccumulation in in situ caged benthic invertebrates. Radium-226 bioaccumulation from sediment and water was evaluated using caged oligochaetes (Lumbriculus variegatus) deployed for 10 d in 6 areas downstream of decommissioned uranium operations in Ontario and Saskatchewan, Canada. Measured (226) Ra radioactivity levels in the retrieved oligochaetes did not relate directly to water and sediment exposure levels. Other environmental factors that may influence (226) Ra bioavailability in sediment and water were investigated. The strongest mitigating influence on (226) Ra bioaccumulation factors was sediment barium concentration, with elevated barium (Ba) levels being related to use of barium chloride in effluent treatment for removing (226) Ra through barite formation. Observations from the present study also indicated that (226) Ra bioavailability was influenced by dissolved organic carbon in water, and by gypsum, carbonate minerals, and iron oxyhydroxides in sediment, suggestive of sorption processes. Environmental factors that appeared to increase (226) Ra bioaccumulation were the presence of other group (II) ions in water (likely competing for binding sites on organic carbon molecules), and the presence of K-feldspars in sediment, which likely act as a dynamic repository for (226) Ra where weak ion exchange can occur. In addition to influencing bioavailability to sediment biota, secondary minerals such as gypsum, carbonate minerals, and iron oxyhydroxides likely help mitigate (226) Ra release into overlying water after the dissolution of sedimentary barite. Environ Toxicol Chem 2015;34:507-517. © 2014 SETAC.
Yoram Teitler - One of the best experts on this subject based on the ideXlab platform.
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effective Radium 226 concentration in meteorites
Geochimica et Cosmochimica Acta, 2017Co-Authors: Frédéric Girault, Frédéric Perrier, Manuel Moreira, Brigitte Zanda, Pierre Rochette, Yoram TeitlerAbstract:The analysis of noble gases in meteorites provides constraints on the early solar system and the pre-solar nebula. This requires a better characterization and understanding of the capture, production, and release of noble gases in meteorites. The knowledge of transfer properties of noble gases for each individual meteorite could benefit from using radon-222, radioactive daughter of Radium-226. The radon-222 emanating power is commonly quantified by the effective Radium-226 concentration (ECRa), the product of the bulk Radium-226 concentration and of the emanation coefficient E, which represents the probability of one decaying Radium-226 to inject one radon-222 into the free porous network. Owing to a non-destructive, high-sensitivity accumulation method based on long photomultiplier counting sessions, we are now able to measure ECRa of meteorite samples, which usually have mass smaller than 15 g and ECRa < 0.5 Bq kg−1. We report here the results obtained from 41 different meteorites, based on 129 measurements on 70 samples using two variants of our method, showing satisfactory repeatability and a detection limit below 10−2 Bq kg−1 for a sample mass of 1 g. While two meteorites remain below detection level, we obtain for 39 meteorites heterogeneous ECRa values with mean (min–max range) of ca. 0.1 (0.018–1.30) Bq kg−1. Carbonaceous chondrites exhibit the largest ECRa values and eucrites the smallest. Such values are smaller than typical values from most terrestrial rocks, but comparable with those from Archean rocks (mean of ca. 0.18 Bq kg−1), an end-member of terrestrial rocks. Using uranium concentration from the literature, E is inferred from ECRa for all the meteorite samples. Values of E for meteorites (mean 40 ± 4%) are higher than E values for Archean rocks and reported values for lunar and Martian soils. Exceptionally large E values likely suggest that the 238U-226Ra pair would not be at equilibrium in most meteorites and that uranium and/or Radium are most likely not uniformly distributed. ECRa of meteorites is correlated with E and seems to mainly reflect the gas permeability of the meteorite, which could be one important property, preserved in the meteorite, of its parent body, characterizing its history in space, possibly modified by alteration, shock metamorphism, and eventually weathering on Earth. Larger radon emanation values are associated with larger concentrations of the heaviest noble gases (argon, krypton, xenon), and larger 20Ne/22Ne and 36Ar/38Ar ratios, suggesting Earth’s atmosphere contamination or solar wind implantation, and probably a similar carrier phase such as Q phase. An unclear correlation is observed with 40Ar, which may rule out a purely radiogenic effect on radon emanation. Thus, larger radon emanation suggests a larger capacity of collecting solar and terrestrial gases, which should imply higher loss of gases generated in the meteorite and larger dispersion of Pb/U ratios for age determination. This study provides the first quantification of natural radon-222 loss from meteorites and opens promising perspectives to quantify the relationship between pore space connectivity and the transfer properties for noble gases in meteorites and other extraterrestrial bodies.
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Effective Radium-226 concentration in meteorites
Geochimica et Cosmochimica Acta, 2017Co-Authors: Frédéric Girault, Frédéric Perrier, Manuel Moreira, Brigitte Zanda, Pierre Rochette, Yoram TeitlerAbstract:The analysis of noble gases in meteorites provides constraints on the early solar system and the pre-solar nebula. This requires a better characterization and understanding of the capture, production, and release of noble gases in meteorites. The knowledge of transfer properties of noble gases for each individual meteorite could benefit from using radon-222, radioactive daughter of Radium-226. The radon-222 emanating power is commonly quantified by the effective Radium-226 concentration (ECRa), the product of the bulk Radium-226 concentration and of the emanation coefficient E, which represents the probability of one decaying Radium-226 to inject one radon-222 into the free porous network. Owing to a non-destructive, high-sensitivity accumulation method based on long photomultiplier counting sessions, we are now able to measure ECRa of meteorite samples, which usually have mass smaller than 15 g and ECRa
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Effective Radium-226 concentration in meteorites
Geochimica et Cosmochimica Acta, 2017Co-Authors: Frédéric Girault, Frédéric Perrier, Manuel Moreira, Brigitte Zanda, Pierre Rochette, Yoram TeitlerAbstract:The analysis of noble gases in meteorites provides constraints on the early solar system and the pre-solar nebula. This requires a better characterization and understanding of the capture, production, and release of noble gases in meteorites. The knowledge of transfer properties of noble gases for each individual meteorite could benefit from using radon-222, radioactive daughter of Radium-226. The radon-222 emanating power is commonly quantified by the effective Radium-226 concentration (ECRa), the product of the bulk Radium-226 concentration and of the emanation coefficient E, which represents the probability of one decaying Radium-226 to inject one radon-222 into the free porous network. Owing to a non-destructive, high-sensitivity accumulation method based on long photomultiplier counting sessions, we are now able to measure ECRa of meteorite samples, which usually have mass smaller than 15 g and ECRa < 0.5 Bq kg(-1). We report here the results obtained from 41 different meteorites, based on 129 measurements on 70 samples using two variants of our method, showing satisfactory repeatability and a detection limit below 10(-2) Bq kg(-1) for a sample mass of 1 g. While two meteorites remain below detection level, we obtain for 39 meteorites heterogeneous ECRa values with mean (min-max range) of ca. 0.1 (0.0181.30) Bq kg(-1). Carbonaceous chondrites exhibit the largest ECRa values and eucrites the smallest. Such values are smaller than typical values from most terrestrial rocks, but comparable with those from Archean rocks (mean of ca. 0.18 Bq kg(-1)), an end-member of terrestrial rocks. Using uranium concentration from the literature, E is inferred from ECRa for all the meteorite samples. Values of E for meteorites (mean 40 +/- 4%) are higher than E values for Archean rocks and reported values for lunar and Martian soils. Exceptionally large E values likely suggest that the U-238-Ra-226 pair would not be at equilibrium in most meteorites and that uranium and/or Radium are most likely not uniformly distributed. ECRa of meteorites is correlated with E and seems to mainly reflect the gas permeability of the meteorite, which could be one important property, preserved in the meteorite, of its parent body, characterizing its history in space, possibly modified by alteration, shock metamorphism, and eventually weathering on Earth. Larger radon emanation values are associated with larger concentrations of the heaviest noble gases (argon, krypton, xenon), and larger Ne-20/Ne-22 and Ar-36/Ar-38 ratios, suggesting Earth's atmosphere contamination or solar wind implantation, and probably a similar carrier phase such as Q phase. An unclear correlation is observed with Ar-40, which may rule out a purely radiogenic effect on radon emanation. Thus, larger radon emanation suggests a larger capacity of collecting solar and terrestrial gases, which should imply higher loss of gases generated in the meteorite and larger dispersion of Pb/U ratios for age determination. This study provides the first quantification of natural radon-222 loss from meteorites and opens promising perspectives to quantify the relationship between pore space connectivity and the transfer properties for noble gases in meteorites and other extraterrestrial bodies. (C) 2017 Elsevier Ltd. All rights reserved.