Characterization of uranium redox state in organic-rich Eocene sediments
The presence of organic matter (OM) has a profound impact on uranium (U) redox cycling, either limiting or promoting the mobility of U via binding, reduction, or complexation. To understand the interactions between OM and U, we characterised U oxidation state and speciation in nine OM-rich sediment...
| Main Authors: | , , , , , , , |
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| Format: | Journal Article |
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Elsevier
2018
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| Online Access: | http://hdl.handle.net/20.500.11937/60603 |
| _version_ | 1848760619301339136 |
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| author | Cumberland, S. Etschmann, B. Brugger, J. Douglas, G. Evans, Katy Fisher, L. Kappen, P. Moreau, J. |
| author_facet | Cumberland, S. Etschmann, B. Brugger, J. Douglas, G. Evans, Katy Fisher, L. Kappen, P. Moreau, J. |
| author_sort | Cumberland, S. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The presence of organic matter (OM) has a profound impact on uranium (U) redox cycling, either limiting or promoting the mobility of U via binding, reduction, or complexation. To understand the interactions between OM and U, we characterised U oxidation state and speciation in nine OM-rich sediment cores (18 samples), plus a lignite sample from the Mulga Rock polymetallic deposit in Western Australia. Uranium was unevenly dispersed within the analysed samples with 84% of the total U occurring in samples containing > 21 wt % OM. Analyses of U speciation, including x-ray absorption spectroscopy and bicarbonate extractions, revealed that U existed predominately (~71%) as U(VI), despite the low pH (4.5) and nominally reducing conditions within the sediments. Furthermore, low extractability by water, but high extractability by a bi-carbonate solution, indicated a strong association of U with particulate OM. The unexpectedly high proportion of U(VI) relative to U(IV) within the OM-rich sediments implies that OM itself does not readily reduce U, and the reduction of U is not a requirement for immobilizing uranium in OM-rich deposits. The fact that OM can play a significant role in limiting the mobility and reduction of U(VI) in sediments is important for both U-mining and remediation. |
| first_indexed | 2025-11-14T10:18:39Z |
| format | Journal Article |
| id | curtin-20.500.11937-60603 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T10:18:39Z |
| publishDate | 2018 |
| publisher | Elsevier |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-606032020-09-04T06:09:04Z Characterization of uranium redox state in organic-rich Eocene sediments Cumberland, S. Etschmann, B. Brugger, J. Douglas, G. Evans, Katy Fisher, L. Kappen, P. Moreau, J. The presence of organic matter (OM) has a profound impact on uranium (U) redox cycling, either limiting or promoting the mobility of U via binding, reduction, or complexation. To understand the interactions between OM and U, we characterised U oxidation state and speciation in nine OM-rich sediment cores (18 samples), plus a lignite sample from the Mulga Rock polymetallic deposit in Western Australia. Uranium was unevenly dispersed within the analysed samples with 84% of the total U occurring in samples containing > 21 wt % OM. Analyses of U speciation, including x-ray absorption spectroscopy and bicarbonate extractions, revealed that U existed predominately (~71%) as U(VI), despite the low pH (4.5) and nominally reducing conditions within the sediments. Furthermore, low extractability by water, but high extractability by a bi-carbonate solution, indicated a strong association of U with particulate OM. The unexpectedly high proportion of U(VI) relative to U(IV) within the OM-rich sediments implies that OM itself does not readily reduce U, and the reduction of U is not a requirement for immobilizing uranium in OM-rich deposits. The fact that OM can play a significant role in limiting the mobility and reduction of U(VI) in sediments is important for both U-mining and remediation. 2018 Journal Article http://hdl.handle.net/20.500.11937/60603 10.1016/j.chemosphere.2017.12.012 Elsevier fulltext |
| spellingShingle | Cumberland, S. Etschmann, B. Brugger, J. Douglas, G. Evans, Katy Fisher, L. Kappen, P. Moreau, J. Characterization of uranium redox state in organic-rich Eocene sediments |
| title | Characterization of uranium redox state in organic-rich Eocene sediments |
| title_full | Characterization of uranium redox state in organic-rich Eocene sediments |
| title_fullStr | Characterization of uranium redox state in organic-rich Eocene sediments |
| title_full_unstemmed | Characterization of uranium redox state in organic-rich Eocene sediments |
| title_short | Characterization of uranium redox state in organic-rich Eocene sediments |
| title_sort | characterization of uranium redox state in organic-rich eocene sediments |
| url | http://hdl.handle.net/20.500.11937/60603 |