Radionuclides in Manganese nodules
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PANGAEA
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| Format: | Dataset Open Access |
| Sprache: | en |
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PANGAEA
1978
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| _version_ | 1867167675992506368 |
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| author | Guichard, Francois |
| author_facet | Guichard, Francois |
| collection | Datos científicos de ciencias marinas y ambientales |
| contents | Manganese nodules are considered to have accumulated in general very slowly: surface layers of nodules contain a large excess of 230Th, more than would be produced by uranium decay. The decrease of excess 230Th with depth within a nodule is generally interpreted to be due to the radioactive decay, and nodule accumulation rates were then estimated from this to be a few mm/Myr. How then do these nodules escape from burial by associated marine sediments which accumulate 3 orders of magnitude faster than the nodules? One possible explanation is that the radionuclides of interest were not incorporated in the nodule matrix during its growth but were adsorbed later. Subsequent inward diffusion of the radionuclides might result in an apparent radioactive decay. We have tested this hypothesis by measuring simultaneously two radionuclides of different half lives. If the gradients of the radionuclides are really due to the radioactive decay, then, assuming a constant growth rate for a nodule, we expect the profile of the shortlived nuclide to be steeper (because of its faster decay) than that of the longlived nuclide. |
| format | Dataset Open Access |
| id | pangaea_https___doi_org_10_1594_PANGAEA_887966 |
| institution | PANGAEA |
| language | en |
| publishDate | 1978 |
| publisher | PANGAEA |
| record_format | pangaea |
| spellingShingle | Radionuclides in Manganese nodules Guichard, Francois Dredge; DRG; Marara; NIXO10; NOAA and MMS Marine Minerals Geochemical Database; NOAA-MMS; NX10-CL; Pacific Ocean; TECHNO 07 Manganese nodules are considered to have accumulated in general very slowly: surface layers of nodules contain a large excess of 230Th, more than would be produced by uranium decay. The decrease of excess 230Th with depth within a nodule is generally interpreted to be due to the radioactive decay, and nodule accumulation rates were then estimated from this to be a few mm/Myr. How then do these nodules escape from burial by associated marine sediments which accumulate 3 orders of magnitude faster than the nodules? One possible explanation is that the radionuclides of interest were not incorporated in the nodule matrix during its growth but were adsorbed later. Subsequent inward diffusion of the radionuclides might result in an apparent radioactive decay. We have tested this hypothesis by measuring simultaneously two radionuclides of different half lives. If the gradients of the radionuclides are really due to the radioactive decay, then, assuming a constant growth rate for a nodule, we expect the profile of the shortlived nuclide to be steeper (because of its faster decay) than that of the longlived nuclide. |
| title | Radionuclides in Manganese nodules |
| topic | Dredge; DRG; Marara; NIXO10; NOAA and MMS Marine Minerals Geochemical Database; NOAA-MMS; NX10-CL; Pacific Ocean; TECHNO 07 |
| url | https://doi.org/10.1594/PANGAEA.887966 |