Ocean thermohaline circulation and sedimentary 231Pa/230Th ratio ...
Holocene sediments from the Atlantic are characterized by 231Pa/230Th ratios below the production ratio of the two radionuclides in the water column (0.093), whereas Holocene sediments from the Southern Ocean have 231Pa/230Th > 0.093. This pattern of 231Pa deficit and excess was ascribed to south...
| Main Authors: | , , , |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
University of Bern
2000
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| Subjects: | |
| Online Access: | https://dx.doi.org/10.48350/158214 https://boris-portal.unibe.ch/handle/20.500.12422/42975 |
| Summary: | Holocene sediments from the Atlantic are characterized by 231Pa/230Th ratios below the production ratio of the two radionuclides in the water column (0.093), whereas Holocene sediments from the Southern Ocean have 231Pa/230Th > 0.093. This pattern of 231Pa deficit and excess was ascribed to southward 231Pa export from the Atlantic by the Atlantic thermohaline circulation (THC) as Pa is scavenged less efficiently by marine particles and more effectively transported by the THC than Th. The same pattern is observed in deposits of the Last Glacial Maximum (LGM), which led to a previous contention that the THC strength did not vary markedly through the last glacial termination. Here we embed a description of trace metal scavenging into a zonally averaged, circulation-biogeochemistry ocean model to explore the sensitivity of 231Pa/230Th in Atlantic and Southern Ocean sediments to THC changes. Our results show that the production of biogenic opal (which, unlike other marine particles, poorly fractionates Th and ... |
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