Vertical migration of 134Cs bearing soil particles in arid soils: implications for plutonium redistribution

Whicker, Randy; Ibrahim, Shawki A.

doi:10.1016/j.jenvrad.2006.01.010

Cited by 11 publications

(6 citation statements)

References 17 publications

(16 reference statements)

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“…A review of the relevant literature confirms that the artificial radionuclides, caesium‐134 ( 134 Cs) ( t 0.5 = 2 · 06 years; measured at 604 keV) and cobalt‐60 ( 60 Co) ( t 0.5 = 5 · 26 years; measured at 1171 keV) satisfy the criteria outlined earlier (Cremers et al ., ; Avery, ; Matishov et al ., ; Real et al ., ; Galabov et al ., ; Khan, ; Caron and Mankarios, ; Payne et al ., ; Shinonaga et al ., ; Whicker and Ibrahim, ; Chen and Lu, ). Although both radionuclides have previously been used as sediment tracers (e.g.…”

Section: Introductionmentioning

confidence: 99%

Using caesium‐134 and cobalt‐60 as tracers to assess the remobilization of recently‐deposited overbank‐derived sediment on river floodplains during subsequent inundation events

Greenwood

Walling

Quine

2013

Earth Surf Processes Landf

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River floodplains act as sinks for fine‐sediment and sediment‐associated contaminants. Increasing recognition of their environmental importance has necessitated a need for an improved understanding of the fate and residence times of overbank sediment deposits over a broad range of timescales. Most existing investigations have focused on medium‐term accretion rates, which represents net deposition from multiple flood events over several decades. In contrast, the fate of recently‐deposited sediment during subsequent overbank events has received only limited attention. This paper presents a novel tracing‐technique for documenting the remobilization of recent overbank sediment on river floodplains during subsequent inundation events, using the artificial radionuclides, caesium‐134 (134Cs) and cobalt‐60 (60Co). The investigation was conducted within floodplains of the Rivers Taw and Culm in Devon, UK. Small quantities of fine‐sediment (< 63 µm dia.), pre‐labelled with known activities of either 134Cs or 60Co, were deposited at 15 locations across each floodplain. Surface inventories, measured before and after three consecutive flood events, were used to estimate sediment loss (in g m–2). Significant reductions provided evidence of the remobilization of the labelled sediment by inundating floodwaters. Spatial variations in remobilization were related to localized topography. Sediment remobilized during the first two events for the River Taw floodplain were equivalent to 63 · 8% and 11 · 9%, respectively, of the original mass. Equivalent values for the River Culm floodplain were 49 · 6% and 12 · 5%, respectively, of the original mass. Sediment loss during the third event proved too small to be attributed to remobilization by overbank floodwaters. After the third event, a mean of 22 · 5% and 35 · 2% of the original mass remained on the Taw and Culm floodplains, respectively. These results provide evidence of the storage of the remaining sediment. The findings highlight the importance of remobilization of recently‐deposited sediment on river floodplains during subsequent overbank events and demonstrate the potential of the tracing‐technique. Copyright © 2013 John Wiley & Sons, Ltd.

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Section: Introductionmentioning

confidence: 99%

Using caesium‐134 and cobalt‐60 as tracers to assess the remobilization of recently‐deposited overbank‐derived sediment on river floodplains during subsequent inundation events

Greenwood

Walling

Quine

2013

Earth Surf Processes Landf

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“…This suggests that the vertical migration of U through the soil is partly realized under microparticle forms. This observation is not surprising since on the one hand, residual U particles are classically identified in surface soils in comparable contexts (firing test ranges or battlefields from Kosovo and Kuwait conflicts ,,,, ), and on the other hand, vertical migration of particles is known to occur in soils, enhancing the transport of radioactive fallouts through topsoil horizons. − The speciation of these microparticles could not be studied within the framework of this research because their size (of the order of a few micrometers) is smaller than the lowest size of the synchrotron beam achievable on the MARS beamline. The dominant contribution of the uranium-humic substance complex from 10 to about 60 cm suggests that organic matter is one of the principal complexing agents of U during its migration in the first few decimeters. This is confirmed by sorption isotherms onto chalky soil and onto chalk doped with humic acids, which clearly highlights the part taken by humic substances for complexation and immobilization of U in the chalky soil.…”

Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 94%

Uranium Speciation in a Chalky Soil

Bayle

Beccia

Moulin

et al. 2023

Environ. Sci. Technol.

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In this article, the speciation and behavior of anthropogenic metallic uranium deposited on natural soil are approached by combining EXAFS (extended X-ray absorption fine structure) and TRLFS (time-resolved laser-induced fluorescence spectroscopy). First, uranium (uranyl) speciation was determined along the vertical profile of the soil and bedrock by linear combination fitting of the EXAFS spectra. It shows that uranium migration is strongly limited by the sorption reaction onto soil and rock constituents, mainly mineral carbonates and organic matter. Second, uranium sorption isotherms were established for calcite, chalk, and chalky soil materials along with EXAFS and TRLFS analysis. The presence of at least two adsorption complexes of uranyl onto carbonate materials (calcite) could be inferred from TRLFS. The first uranyl tricarbonate complex has a liebigite-type structure and is dominant for low loads on the carbonate surface (<10 mgU/kg(rock)). The second uranyl complex is incorporated into the calcite for intermediate (∼10 to 100 mgU/kg(rock)) to high (high: >100 mgU/kg(rock)) loads. Finally, the presence of a uranium-humic substance complex in subsurface soil materials was underlined in the EXAFS analysis by the occurrence of both monodentate and bidentate carboxylate (or/and carbonate) functions and confirmed by sorption isotherms in the presence of humic acid. This observation is of particular interest since humic substances may be mobilized from soil, potentially enhancing uranium migration under colloidal form.

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“…The results indicate that the migration of nuclides at site B is significantly more active at site B compared to site A. This can be attributed to the removal of fine particles with a high affinity for radionuclides caused by soil erosion, as well as the increased permeability resulting from larger remaining soil particles that create larger voids, thereby facilitating downward water infiltration . Consequently, both the migration and diffusion rates of radionuclides are accelerated.…”

Section: Resultsmentioning

confidence: 99%

Migration of Fallout Radionuclides and Soil Erosion of Hongsongwa Mountainous in China

Guan,

Cui,

Huang

et al. 2024

ACS Earth Space Chem.

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To study the effect of soil erosion on the distribution and migration pattern of radionuclides, the levels of 239+240 Pu and 137 Cs in alpine meadow soil were measured in the Hongsongwa Nature Reserve, Hebei Province. The measured activities of 239+240 Pu and 137 Cs in surface soil ranged from 0.028 to 2.781 Bq/kg and from 1.3 to 59.8 Bq/kg, respectively. The distribution of 137 Cs and 239+240 Pu is uneven and significantly correlated with the organic matter content and altitude variations within the study area. Core samples were collected from both ridge and valley locations to assess erosion rates, revealing that ridge areas experienced approximately 2.5 times higher erosion rates (18.0 t ha −l a −1 ) compared to valleys (7.3 t ha −l a −1 ). The vertical migration behavior of 239+240 Pu and 137 Cs was quantitatively described by a convection-diffusion equation model. Results indicated that core samples taken from the ridge displayed significantly higher apparent diffusion coefficients (D Cs = 4.57 cm 2 /y; D Pu = 2.42 cm 2 /y) as well as apparent convection coefficient (ν Cs = 0.31 cm/y; ν Pu = 0.43 cm/y), which were approximately 10 and 2 times those observed in reference sample (D Cs = 0.33 cm 2 /y; D Pu = 0.32 cm 2 /y; ν Cs = 0.16 cm/y; ν Pu = 0.17 cm/y), respectively. The migration rate of 239+240 Pu is accelerated by 39% compared to that of 137 Cs due to soil erosion. The diffusion and convection rates of both isotopes in the valley sample are similar to those in the reference sample. In general, soil erosion significantly affects the horizontal and vertical migration of 239+240 Pu and 137 Cs.

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Vertical migration of 134Cs bearing soil particles in arid soils: implications for plutonium redistribution

Cited by 11 publications

References 17 publications

Using caesium‐134 and cobalt‐60 as tracers to assess the remobilization of recently‐deposited overbank‐derived sediment on river floodplains during subsequent inundation events

Using caesium‐134 and cobalt‐60 as tracers to assess the remobilization of recently‐deposited overbank‐derived sediment on river floodplains during subsequent inundation events

Uranium Speciation in a Chalky Soil

Migration of Fallout Radionuclides and Soil Erosion of Hongsongwa Mountainous in China

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