Distribution of 230Th and 231Pa in the water column in relation to the ventilation of the deep Arctic basins

Scholten, Jan; Loeff, Michiel M Rutgers van der; Michel, A.

doi:10.1016/0967-0645(95)00052-6

Cited by 70 publications

(107 citation statements)

References 26 publications

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“…The average ratio for HS1 (0.074 ± 0.009; n ¼ 26) is somewhat greater than the LGM value, but not significantly different at the 95% confidence level; this study 15,16,21,22,25,27,30,39,40,54 . The average 231 Pa/ 230 Th ratio in Holocene sediment north of 50°S (0.070 ± 0.004; n ¼ 165) is greater than Yu et al, a result that is significant at the 95% confidence level (Yu et al Holocene 231 Pa/ 230 Th: 0.060 ± 0.004; n ¼ 68); this study 1,15,16,[20][21][22]25,27,28,30,39,40,[54][55][56][57][58][59][60][61][62][63][64][65][66] . Because many of the older data were generated using alpha counting, the relative errors are somewhat larger.…”

Section: Discussionmentioning

confidence: 75%

231Pa/230Th evidence for a weakened but persistent Atlantic meridional overturning circulation during Heinrich Stadial 1

2014

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The strength of Atlantic meridional overturning circulation is believed to affect the climate over glacial-interglacial and millennial timescales. The marine sedimentary 231 Pa/ 230 Th ratio is a promising paleocirculation proxy, but local particle effects may bias individual reconstructions. Here we present new Atlantic sedimentary 231 Pa/ 230 Th data from the Holocene, the last glacial maximum and Heinrich Stadial 1, a period of abrupt cooling ca. 17,500 years ago. We combine our results with published data from these intervals to create a spatially distributed sedimentary 231 Pa/ 230 Th database. The data reveal a net 231 Pa deficit during each period, consistent with persistent 231 Pa export. In highly resolved cores, Heinrich 231 Pa/ 230 Th ratios exceed glacial ratios at nearly all depths, indicating a significant reduction, although not cessation, of overturning during Heinrich Stadial 1. These results support the inference that weakened overturning was a driver of Heinrich cooling, while suggesting that abrupt climate oscillations do not necessarily require a complete shutdown of overturning.

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Section: Discussionmentioning

confidence: 75%

231Pa/230Th evidence for a weakened but persistent Atlantic meridional overturning circulation during Heinrich Stadial 1

2014

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“…The few studies of (Scholten et al, 1995), and lower values in the Beaufort Sea (Edmonds et al, 1998), and in the Amundsen and Nansen Basins (Cochran et al, 1995). These variations may reflect Our findings of relatively balanced budgets at these sites prior to the deglaciation are important for understanding longer-term thorium cycle dynamics in the Arctic.…”

Section: Previous Estimates Of Arctic 230 Th Burialmentioning

confidence: 80%

“…The Arctic thus appears fundamentally similar to other ocean basins in its 231 Pa and 230 Th dynamics, despite its peculiar qualities of sea ice cover, low particle flux, and relatively isolated deep waters. Th ratios from this study, Moran et al (2005) and …....205 Scholten et al (1995). …”

mentioning

confidence: 79%

“…Pa in the water column (Edmonds et al, 1998;Edmonds et al, 2004;Scholten et al, 1995) and in surface sediments of the Arctic has done a great deal to improve our understanding of the behavior of these nuclides in the Arctic, including the possibility of their export to the Atlantic. Downcore sedimentary studies to establish the history of the Arctic budgets and distribution will be key to using these nuclides as paleoproxies in the Atlantic.…”

mentioning

confidence: 99%

“…Basin Scholten et al, 1995;Edmonds et al, 2004) to rates comparable to the rest of the world ocean in the Nansen Basin and the Canada Basin (Cochran et al, 1995;Scholten et al, 1995;Edmonds et al, 1998;Trimble et al, 2004).…”

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confidence: 99%

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Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean

Hoffmann¹

2009

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The radionuclides 231 Pa and 230 Th, produced in the water column and removed from the ocean by particle scavenging and burial in sediments, offer a means for paleoceanographers to examine past dynamics of both water column and sedimentary processes. I show for the first time that a state of balance exists between 230 Th production and burial in the Central Arctic basins, based on measured sedimentary 230 Th xs inventories in box cores, establishing this nuclide's utility as a paleoceanographic indicator of sedimentary processes and as a normalization tool. I present the first 230 Th-normalized particle fluxes calculated for the central Arctic: vertical particle fluxes were extremely low during the late glacial, rose during the deglaciation due to particle inputs from shelf inundation, increased productivity and ice-rafted debris, and fell again following the establishment of interglacial conditions. A major event of lateral sediment redistribution, inferred from surplus 230 Th xs inventories, occurred in the Makarov Basin during the deglaciation and may have been due to destabilization of slope and shelf sediments as sea level rose.I present the first high-resolution, radiocarbon-dated downcore records of sedimentary 231 Pa/ 230 Th from the Arctic Ocean. Low ratios indicate that 231 Pa was exported from all sites during the late glacial period, with export decreasing during the deglaciation and Holocene.231 Pa/ 230 Th measurements in cores from three continental slope sites show no evidence for a 231 Pa sink related to boundary scavenging on the continental slopes. Holocene 231 Pa/ 230 Th ratios show a very significant variation by depth, with strong export of 231 Pa at deep sites but little or no export at shallow sites, a result which echoes findings for the South Atlantic and the Pacific. The Arctic thus appears fundamentally similar to other ocean basins in its 231 Pa and 230 Th dynamics, despite its peculiar qualities of sea ice cover, low particle flux, and relatively isolated deep waters.

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Controls on ²³¹Pa and ²³⁰Th in the Arctic Ocean

Luo

Lippold

2015

Geophysical Research Letters

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The distributions of 230Th and 231Pa in the Arctic Ocean are not well understood. In order to examine the Arctic 231Pa/230Th system and therefore to shed light on the future use of Arctic sedimentary 231Pa/230Th, we developed a 2‐D scavenging model modified from an Atlantic model. Tuned with reasonable parameters that are consistent with Eurasian Basin geographic settings, the model can reproduce most of the features of the 230Th and 231Pa water column profiles as well as the sedimentary 231Pa/230Th distribution patterns and suggests that the sedimentary 231Pa/230Th in the Eurasian Basin is mainly controlled by the deep water circulation. In our attempt to reproduce the sedimentary 231Pa/230Th patterns during the last glacial, we found that circulation strength in the Eurasian Basin at shallower depths may have been stronger than today.

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Distribution of 230Th and 231Pa in the water column in relation to the ventilation of the deep Arctic basins

Cited by 70 publications

References 26 publications

231Pa/230Th evidence for a weakened but persistent Atlantic meridional overturning circulation during Heinrich Stadial 1

231Pa/230Th evidence for a weakened but persistent Atlantic meridional overturning circulation during Heinrich Stadial 1

Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean

Controls on ²³¹Pa and ²³⁰Th in the Arctic Ocean

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Distribution of 230Th and 231Pa in the water column in relation to the ventilation of the deep Arctic basins

Cited by 70 publications

References 26 publications

231Pa/230Th evidence for a weakened but persistent Atlantic meridional overturning circulation during Heinrich Stadial 1

231Pa/230Th evidence for a weakened but persistent Atlantic meridional overturning circulation during Heinrich Stadial 1

Uranium-series radionuclide records of paleoceanographic and sedimentary changes in the Arctic Ocean

Controls on 231Pa and 230Th in the Arctic Ocean

Contact Info

Product

Resources

About

Controls on ²³¹Pa and ²³⁰Th in the Arctic Ocean