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| Auteurs principaux: | , , |
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| Format: | Dataset Open Access |
| Langue: | en |
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PANGAEA
2012
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| Accès en ligne: | https://doi.org/10.1594/PANGAEA.825477 |
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| _version_ | 1867171366901383168 |
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| author | Boiteau, Rene Greaves, Mervyn Elderfield, Henry |
| author_facet | Boiteau, Rene Greaves, Mervyn Elderfield, Henry |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | The rate of uranium accumulation in oceanic sediments from seawater is controlled by bottom water oxygen concentrations and organic carbon fluxes-two parameters that are linked to deep ocean storage of CO2. To investigate glacial-interglacial changes in what is known as authigenic U, we have developed a rapid method for its determination as a simple addition to a procedure for foraminiferal trace element analysis. Foraminiferal calcite acts as a low U substrate (U/Ca < 15 nmol/mol) upon which authigenic U accumulates in reducing sediments. We measured a downcore record of foraminiferal U/Ca from ODP Site 1090 in the South Atlantic and found that U/Ca ratios increase by 70-320 nmol/mol during glacial intervals. There is a significant correlation between U/Ca records of benthic and planktonic foraminiferal species and between U/Ca and bulk sediment authigenic U. These results indicate that elevated U/Ca ratios are attributable to the accumulation of authigenic U coatings in sediments. Foraminiferal Mn/Ca ratios were lower during the glacial intervals, suggesting that the observed U accumulation on the shells is not directly linked to U incorporation into secondary manganese phases. Thus, foraminiferal U/Ca ratios may provide useful information on past changes in sediment redox conditions. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_825477 |
| institution | PANGAEA |
| language | en |
| publishDate | 2012 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Foraminiferal trace element ratios from South Atlantic sediments Boiteau, Rene Greaves, Mervyn Elderfield, Henry Ocean Drilling Program; ODP The rate of uranium accumulation in oceanic sediments from seawater is controlled by bottom water oxygen concentrations and organic carbon fluxes-two parameters that are linked to deep ocean storage of CO2. To investigate glacial-interglacial changes in what is known as authigenic U, we have developed a rapid method for its determination as a simple addition to a procedure for foraminiferal trace element analysis. Foraminiferal calcite acts as a low U substrate (U/Ca < 15 nmol/mol) upon which authigenic U accumulates in reducing sediments. We measured a downcore record of foraminiferal U/Ca from ODP Site 1090 in the South Atlantic and found that U/Ca ratios increase by 70-320 nmol/mol during glacial intervals. There is a significant correlation between U/Ca records of benthic and planktonic foraminiferal species and between U/Ca and bulk sediment authigenic U. These results indicate that elevated U/Ca ratios are attributable to the accumulation of authigenic U coatings in sediments. Foraminiferal Mn/Ca ratios were lower during the glacial intervals, suggesting that the observed U accumulation on the shells is not directly linked to U incorporation into secondary manganese phases. Thus, foraminiferal U/Ca ratios may provide useful information on past changes in sediment redox conditions. |
| title | Foraminiferal trace element ratios from South Atlantic sediments |
| topic | Ocean Drilling Program; ODP |
| url | https://doi.org/10.1594/PANGAEA.825477 |