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R Avadhanula - One of the best experts on this subject based on the ideXlab platform.
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radionuclides lead 210 polonium 210 Thorium 230 and 232 and Thorium and uranium in water sediments and fish from lakes near the city of elliot lake ontario canada
Environmental Pollution, 1998Co-Authors: F V Clulow, N K Dave, T P Lim, R AvadhanulaAbstract:Abstract Radionuclides (210Pb, 210Po, 230Th, and 232Th) and chemical Th and U were measured in water, sediments, and fish tissues (bone, muscle, and gut contents of laketrout, Salvelinus namaycush, whitefish, Coregonus clupeaformis and Prosopium cylindraceum) from four lakes in a watershed affected by U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent, non-industrialized, watershed. Radionuclide concentration ratios between tissue levels and sediment and water levels were calculated. Annual radionuclide intakes and resulting doses were estimated for humans consuming fish from the watershed. Bone 210Pb levels were higher (186 mBq g−1 dry wt in laketrout and 230 mBq g−1 dry wt in one lake whitefish) than in muscle (
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radionuclides lead 210 polonium 210 Thorium 230 and 232 and Thorium and uranium in water sediments and fish from lakes near the city of elliot lake ontario canada
Environmental Pollution, 1998Co-Authors: F V Clulow, N K Dave, R AvadhanulaAbstract:Radionuclides (210Pb, 210Po, 230Th, and 232Th) and chemical Th and U were measured in water, sediments, and fish tissues (bone, muscle, and gut contents of laketrout, Salvelinus namaycush, whitefish, Coregonus clupeaformis and Prosopium cylindraceum) from four lakes in a watershed affected by U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent, non-industrialized, watershed. Radionuclide concentration ratios between tissue levels and sediment and water levels were calculated. Annual radionuclide intakes and resulting doses were estimated for humans consuming fish from the watershed. Bone 210Pb levels were higher (186 mBq g−1 dry wt in laketrout and 230 mBq g−1 dry wt in one lake whitefish) than in muscle (< 50 mBq g−1 dry wt in all cases), and generally higher in fish from study lakes than from controls, but no consistent differences were observed among fish species. Similarly, 210Po levels were higher in bone (208 ± 33 mBq g−1, in laketrout) than muscle (maximum 26 ± 4 mBq g−1, in laketrout), and in study lake populations compared to controls. Laketrout 210Po bone concentrations were higher than previously reported in Canada. Levels of 230Th, 232Th, and Th were below detection limits (20 mBq g−1, 0.05 μg g−1) in body tissues in all fish species. Bone levels of U (14.6 ± 3.0 μg g−1, in lake whitefish) were higher than in muscle (most < 0.05 μg g−1, except 0.12 ± 0.04 and 0.08 ± 0.03 μg g−1 in lake whitefish) in fish from waters affected by industrial activity. In control lakes, bone and muscle levels were lower and not significantly different from each other. Muscle levels did not vary consistently with location. Concentration of 210Pb and U was seen from water and ‘gut’ material (taken as a surrogate for diet) to bone in laketrout and whitefish, and of U from water to muscle in whitefish, but in no case from sediments to tissues. Human intakes of 210Pb, 210Po, 230Th, 232Th, and U from consuming one meal of fish (375 g) per week could, in aggregate, represent an annual effective dose < 15% of the public dose limit (5 mSv). Monitoring biota living near the decommissioned Elliot Lake U operations, especially of 210Pb levels in fish muscle, with further assessment of human doses attributable to local fish and other animals in the diet, should continue. Because radionuclide effects on fish health (and on other non-human organisms) are of increasing concern, neoplasms, malformations, and reproductive anomalies in local fish deserve examination.
F V Clulow - One of the best experts on this subject based on the ideXlab platform.
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radionuclides lead 210 polonium 210 Thorium 230 and 232 and Thorium and uranium in water sediments and fish from lakes near the city of elliot lake ontario canada
Environmental Pollution, 1998Co-Authors: F V Clulow, N K Dave, T P Lim, R AvadhanulaAbstract:Abstract Radionuclides (210Pb, 210Po, 230Th, and 232Th) and chemical Th and U were measured in water, sediments, and fish tissues (bone, muscle, and gut contents of laketrout, Salvelinus namaycush, whitefish, Coregonus clupeaformis and Prosopium cylindraceum) from four lakes in a watershed affected by U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent, non-industrialized, watershed. Radionuclide concentration ratios between tissue levels and sediment and water levels were calculated. Annual radionuclide intakes and resulting doses were estimated for humans consuming fish from the watershed. Bone 210Pb levels were higher (186 mBq g−1 dry wt in laketrout and 230 mBq g−1 dry wt in one lake whitefish) than in muscle (
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radionuclides lead 210 polonium 210 Thorium 230 and 232 and Thorium and uranium in water sediments and fish from lakes near the city of elliot lake ontario canada
Environmental Pollution, 1998Co-Authors: F V Clulow, N K Dave, R AvadhanulaAbstract:Radionuclides (210Pb, 210Po, 230Th, and 232Th) and chemical Th and U were measured in water, sediments, and fish tissues (bone, muscle, and gut contents of laketrout, Salvelinus namaycush, whitefish, Coregonus clupeaformis and Prosopium cylindraceum) from four lakes in a watershed affected by U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent, non-industrialized, watershed. Radionuclide concentration ratios between tissue levels and sediment and water levels were calculated. Annual radionuclide intakes and resulting doses were estimated for humans consuming fish from the watershed. Bone 210Pb levels were higher (186 mBq g−1 dry wt in laketrout and 230 mBq g−1 dry wt in one lake whitefish) than in muscle (< 50 mBq g−1 dry wt in all cases), and generally higher in fish from study lakes than from controls, but no consistent differences were observed among fish species. Similarly, 210Po levels were higher in bone (208 ± 33 mBq g−1, in laketrout) than muscle (maximum 26 ± 4 mBq g−1, in laketrout), and in study lake populations compared to controls. Laketrout 210Po bone concentrations were higher than previously reported in Canada. Levels of 230Th, 232Th, and Th were below detection limits (20 mBq g−1, 0.05 μg g−1) in body tissues in all fish species. Bone levels of U (14.6 ± 3.0 μg g−1, in lake whitefish) were higher than in muscle (most < 0.05 μg g−1, except 0.12 ± 0.04 and 0.08 ± 0.03 μg g−1 in lake whitefish) in fish from waters affected by industrial activity. In control lakes, bone and muscle levels were lower and not significantly different from each other. Muscle levels did not vary consistently with location. Concentration of 210Pb and U was seen from water and ‘gut’ material (taken as a surrogate for diet) to bone in laketrout and whitefish, and of U from water to muscle in whitefish, but in no case from sediments to tissues. Human intakes of 210Pb, 210Po, 230Th, 232Th, and U from consuming one meal of fish (375 g) per week could, in aggregate, represent an annual effective dose < 15% of the public dose limit (5 mSv). Monitoring biota living near the decommissioned Elliot Lake U operations, especially of 210Pb levels in fish muscle, with further assessment of human doses attributable to local fish and other animals in the diet, should continue. Because radionuclide effects on fish health (and on other non-human organisms) are of increasing concern, neoplasms, malformations, and reproductive anomalies in local fish deserve examination.
N K Dave - One of the best experts on this subject based on the ideXlab platform.
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radionuclides lead 210 polonium 210 Thorium 230 and 232 and Thorium and uranium in water sediments and fish from lakes near the city of elliot lake ontario canada
Environmental Pollution, 1998Co-Authors: F V Clulow, N K Dave, T P Lim, R AvadhanulaAbstract:Abstract Radionuclides (210Pb, 210Po, 230Th, and 232Th) and chemical Th and U were measured in water, sediments, and fish tissues (bone, muscle, and gut contents of laketrout, Salvelinus namaycush, whitefish, Coregonus clupeaformis and Prosopium cylindraceum) from four lakes in a watershed affected by U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent, non-industrialized, watershed. Radionuclide concentration ratios between tissue levels and sediment and water levels were calculated. Annual radionuclide intakes and resulting doses were estimated for humans consuming fish from the watershed. Bone 210Pb levels were higher (186 mBq g−1 dry wt in laketrout and 230 mBq g−1 dry wt in one lake whitefish) than in muscle (
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radionuclides lead 210 polonium 210 Thorium 230 and 232 and Thorium and uranium in water sediments and fish from lakes near the city of elliot lake ontario canada
Environmental Pollution, 1998Co-Authors: F V Clulow, N K Dave, R AvadhanulaAbstract:Radionuclides (210Pb, 210Po, 230Th, and 232Th) and chemical Th and U were measured in water, sediments, and fish tissues (bone, muscle, and gut contents of laketrout, Salvelinus namaycush, whitefish, Coregonus clupeaformis and Prosopium cylindraceum) from four lakes in a watershed affected by U mining and milling operations at Elliot Lake, Ontario, and from control lakes in an adjacent, non-industrialized, watershed. Radionuclide concentration ratios between tissue levels and sediment and water levels were calculated. Annual radionuclide intakes and resulting doses were estimated for humans consuming fish from the watershed. Bone 210Pb levels were higher (186 mBq g−1 dry wt in laketrout and 230 mBq g−1 dry wt in one lake whitefish) than in muscle (< 50 mBq g−1 dry wt in all cases), and generally higher in fish from study lakes than from controls, but no consistent differences were observed among fish species. Similarly, 210Po levels were higher in bone (208 ± 33 mBq g−1, in laketrout) than muscle (maximum 26 ± 4 mBq g−1, in laketrout), and in study lake populations compared to controls. Laketrout 210Po bone concentrations were higher than previously reported in Canada. Levels of 230Th, 232Th, and Th were below detection limits (20 mBq g−1, 0.05 μg g−1) in body tissues in all fish species. Bone levels of U (14.6 ± 3.0 μg g−1, in lake whitefish) were higher than in muscle (most < 0.05 μg g−1, except 0.12 ± 0.04 and 0.08 ± 0.03 μg g−1 in lake whitefish) in fish from waters affected by industrial activity. In control lakes, bone and muscle levels were lower and not significantly different from each other. Muscle levels did not vary consistently with location. Concentration of 210Pb and U was seen from water and ‘gut’ material (taken as a surrogate for diet) to bone in laketrout and whitefish, and of U from water to muscle in whitefish, but in no case from sediments to tissues. Human intakes of 210Pb, 210Po, 230Th, 232Th, and U from consuming one meal of fish (375 g) per week could, in aggregate, represent an annual effective dose < 15% of the public dose limit (5 mSv). Monitoring biota living near the decommissioned Elliot Lake U operations, especially of 210Pb levels in fish muscle, with further assessment of human doses attributable to local fish and other animals in the diet, should continue. Because radionuclide effects on fish health (and on other non-human organisms) are of increasing concern, neoplasms, malformations, and reproductive anomalies in local fish deserve examination.
Matthieu Roy-barman - One of the best experts on this subject based on the ideXlab platform.
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A global scavenging and circulation ocean model of Thorium-230 and protactinium-231 with improved particle dynamics (NEMO–ProThorP 0.1)
Geoscientific Model Development, 2018Co-Authors: Marco Van Hulten, Jean-claude Dutay, Matthieu Roy-barmanAbstract:Abstract. In this paper we set forth a 3-D ocean model of the radioactive trace isotopes 230Th and 231Pa . The interest arises from the fact that these isotopes are extensively used for investigating particle transport in the ocean and reconstructing past ocean circulation. The tracers are reversibly scavenged by biogenic and lithogenic particles. Our simulations of 230Th and 231Pa are based on the NEMO–PISCES ocean biogeochemistry general circulation model, which includes biogenic particles, namely small and big particulate organic carbon, calcium carbonate and biogenic silica. Small and big lithogenic particles from dust deposition are included in our model as well. Their distributions generally compare well with the small and big lithogenic particle concentrations from recent observations from the GEOTRACES programme, except for boundary nepheloid layers for which, as of today, there are no non-trivial prognostic models available on a global scale. Our simulations reproduce 230Th and 231Pa dissolved concentrations: they compare well with recent GEOTRACES observations in many parts of the ocean. Particulate 230Th and 231Pa concentrations are significantly improved compared to previous studies, but they are still too low because of missing particles from nepheloid layers. Our simulation reproduces the main characteristics of the 231Pa∕230Th ratio observed in the sediments and supports a moderate affinity of 231Pa to biogenic silica as suggested by recent observations relative to 230Th . Future model development may further improve understanding, especially when this will include a more complete representation of all particles, including different size classes, manganese hydroxides and nepheloid layers. This can be done based on our model as its source code is readily available.
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A global scavenging and circulation ocean model of Thorium-230 and protactinium-231 with realistic particle dynamics (NEMO–ProThorP 0.1)
2017Co-Authors: Marco Van Hulten, Jean-claude Dutay, Matthieu Roy-barmanAbstract:Abstract. In this paper, we set forth a 3-D ocean model of the radioactive trace isotopes 230Th and 231Pa. The interest arises from the fact that these isotopes are extensively used for investigating particle transport in the ocean and reconstructing past ocean circulation. The tracers are reversibly scavenged by biogenic and lithogenic particles. Our simulations of 230Th and 231Pa are based on the NEMO–PISCES ocean biogeochemistry general circulation model, which includes biogenic particles, namely small and big particulate organic carbon, calcium carbonate and biogenic silica. Small and big lithogenic particles from dust deposition are included in our model as well. Their distributions generally compare well with the small and big lithogenic particle concentrations from recent observations from the GEOTRACES programme, except for boundary nepheloid layers for which, as up to today, there are no non-trivial, prognostic models available on a global scale. Our simulations reproduce 230Th and 231Pa dissolved concentrations: they compare well with recent GEOTRACES observations in many parts of the ocean. Particulate 230Th and 231Pa concentrations are significantly improved compared to previous studies, but they are still too low because of missing particles from nepheloid layers. Our simulation reproduces the main characteristics of the 231Pa / 230Th ratio observed in the sediments, and supports a moderate affinity of 231Pa to biogenic silica as suggested by recent observations, relative to 230Th. Future model development may further improve understanding, especially when this will include a more complete representation of all particles, including different size classes, manganese hydroxides and nepheloid layers. This can be done based on our model, as its source code is readily available.
Stephanie S. Kienast - One of the best experts on this subject based on the ideXlab platform.
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tracing dust input to the global ocean using Thorium isotopes in marine sediments thoromap
Global Biogeochemical Cycles, 2016Co-Authors: Stephanie S. Kienast, Gisela Winckler, Jorg Lippold, Samuel Albani, N MahowaldAbstract:Continental dust input into the ocean-atmosphere system has significant ramifications for biogeochemical cycles and global climate, yet direct observations of dust deposition in the ocean remain scarce. The long-lived isotope Thorium-232 (232Th) is greatly enriched in upper continental crust compared to oceanic crust and mid-ocean ridge basalt-like volcanogenic material. In open ocean sediments, away from fluvial and ice-rafted sources of continental material, 232Th is often assumed to be of predominantly eolian origin. In conjunction with flux normalization based on the particle reactive radioisotope Thorium-230 (230Th), 232Th measurements in marine sediments are a promising proxy for dust accumulation in the modern and past ocean. Here we present ThoroMap, a new global data compilation of 230Th-normalized fluxes of 232Th. After careful screening, we derive dust deposition estimates in the global ocean averaged for the late Holocene (0–4 ka) and the Last Glacial Maximum (LGM, 19–23 ka). ThoroMap is compared with dust deposition estimates derived from the Community Climate System Model (CCSM3) and CCSM4, two coupled atmosphere, land, ocean, and sea ice models. Model-data correlation factors are 0.63 (CCSM3) and 0.59 (CCSM4) in the late Holocene and 0.82 (CCSM3) and 0.83 (CCSM4) in the LGM. ThoroMap is the first compilation that is built on a single, specific proxy for dust and that exclusively uses flux-normalisation to derive dust deposition rates.
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Thorium 230 normalized particle flux and sediment focusing in the panama basin region during the last 30 000 years
Paleoceanography, 2007Co-Authors: Stephanie S. Kienast, Markus Kienast, Alan C. Mix, Stephen E. Calvert, Roger FrancoisAbstract:[1] Application of the 230 Th normalization method to estimate sediment burial fluxes in six cores from the eastern equatorial Pacific (EEP) reveals that bulk sediment and organic carbon fluxes display a coherent regional pattern during the Holocene that is consistent with modern oceanographic conditions, in contrast with estimates of bulk mass accumulation rates (MARs) derived from core chronologies. Two nearby sites (less than 10 km apart), which have different MARs, show nearly identical 230 Th-normalized bulk fluxes. Focusing factors derived from the 230 Th data at the foot of the Carnegie Ridge in the Panama Basin are >2 in the Holocene, implying that lateral sediment addition is significant in this part of the basin. New geochemical data and existing literature provide evidence for a hydrothermal source of sediment in the southern part of the Panama Basin and for downslope transport from the top of the Carnegie Ridge. The compilation of core records suggests that sediment focusing is spatially and temporally variable in the EEP. During oxygen isotope stage 2 (OIS 2, from 13–27 ka BP), focusing appears even higher compared to the Holocene at most sites, similar to earlier findings in the eastern and central equatorial Pacific. The magnitude of the glacial increase in focusing factors, however, is strongly dependent on the accuracy of age models. We offer two possible explanations for the increase in glacial focusing compared to the Holocene. The first one is that the apparent increase in lateral sediment redistribution is partly or even largely an artifact of insufficient age control in the EEP, while the second explanation, which assumes that the observed increase is real, involves enhanced deep sea tidal current flow during periods of low sea level stand.