The distribution of 230Th and 231Pa in the deep-sea surface sediments of the Pacific Ocean

Yang, Hyun Jin; Nozaki, Yoshiyuki; Sakai, Hitoshi; Masuda, A.

doi:10.1016/0016-7037(86)90050-5

Cited by 89 publications

(64 citation statements)

References 25 publications

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“…On average, the Pa/Th ratio in ocean margin sediments (~ 0.15 to 0.2) is about 4-5 times that in areas of red clay accumulation in the open ocean (~ 0.03-0.04). The pattern of boundary scavenging of 231pa (relative to 23°Th) in this study is in agreement with published results summarized in [20] and our data fill in the Eastern Pacific where some of the 231pa concentrations in [20] were inferred.…”

Section: Intensified Scavenging Of 231pa and L°be In Ocean Marginssupporting

confidence: 93%

“…Four cores (V20-85, V20-88, MANOP Site R and Site S) that have sedimentation rates of~ 2 mm/ky were thus included. Intensified scavenging of Z31pa (relative to 2a°Th) was found in the Northeastern Pacific [20] where we selected eight cores (PS BC 116, 133, 150, 151; SC QP2; W8709A-1, W8709A-8 and W8709A-13) for the purpose of comparing our results with that of the previous study. Of the cores mentioned above, nine constitute a transect across the Pacific along ~ 40°N, serving to study the effect of offshore gradient in sedimentation rate on scavenging of 231pa and l°Be.…”

Section: Core Selection and Resultsmentioning

confidence: 97%

“…Intensified scavenging in ocean margin areas (i.e., boundary scavenging) was shown to greatly influence the removal of particle-reactive chemical substances such as 21°pb [13][14][15][16], Pu isotopes [17] and 231pa [18][19][20][21][22] in the ocean. The results of previous studies [9,10] and our work [23][24][25] have shown that l°Be is also preferentially removed from the oceans in some margin areas.…”

Section: Introductionmentioning

confidence: 99%

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Transport and burial rates of10Be and231Pa in the Pacific Ocean during the Holocene period

Lao

Anderson

Broecker

et al. 1992

Earth and Planetary Science Letters

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Section: Intensified Scavenging Of 231pa and L°be In Ocean Marginssupporting

confidence: 93%

Section: Core Selection and Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Transport and burial rates of10Be and231Pa in the Pacific Ocean during the Holocene period

Lao

Anderson

Broecker

et al. 1992

Earth and Planetary Science Letters

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“…Similar distribution coefficients of Ra and Ac in open ocean environments justify this assumption in many cases. However, actinium is expected to resemble the lanthanides in some aspects, like in its affinity for iron hydroxide, while radium is an alkaline earth metal that tends to be less particle reactive, but co-precipitates with Ac can in theory both be released from continental shelf and slope sediments (Nozaki and Yang, 1987 Pa in shelf sediments: 0.1 dpm*g-1; Yang et al, 1986;Nozaki, 1993 …”

Section: Introductionmentioning

confidence: 99%

“…227 Ac in ground water and pore water Nozaki et al (1990) were the first to report pore water activities of Pa activities of 0.1 dpm/g (Nozaki, 1993), while deep-sea sediments have an average activity of 2.8 dpm/g (Yang et al, 1986 Pa in shelf sediments, which will mostly be found within the crystal lattice (Geibert et al, 2002 Th should be much less affected by the local redox conditions. Alternatively, the values observed in Waquoit Bay groundwater may not be elevated year round, but rather part of a seasonal cycle whereby Ac is loaded onto freshwater sediments during wet periods, then desorbed to brackish groundwater when seawater intrudes into the aquifer during dry periods (Figure 3; Gonneea et al, 2007).…”

Section: Coastal Oceanmentioning

confidence: 99%

The release of dissolved actinium to the ocean: A global comparison of different end-members

et al. 2008

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The measurement of short-lived Ac to the open ocean would have to be included.Ac has so far been considered to behave similarly to Ra in the marine environment, with the exception of a strong Ac source in the deep-sea due to 231 Pa ex . Here, we present evidence of geochemical differences between Ac, which is retained in a warm vent system, and Ra, which is readily released (Moore et al., submitted). Another potential mechanism of producing deviations in 227 Ac/ 228Ra and daughter isotope ratios from the expected production value of lithogenic material is observed at reducing environments, where enrichment in uranium may occur. The presented data here may serve as a reference for including 227 Ac in circulation models, and the overview provides values for some end-members that contribute to the global Ac distribution. IntroductionActinium-227 is a naturally occurring radioisotope with a half-life of 21.77 years. It is generated by decay of protactinium-231, which is particularly abundant in deep-sea sediments. Actinium has a prominent source at the deep ocean floor, in conjunction with a half-life in the range of ocean mixing time scales, which makes it particularly useful as a tracer for deep mixing and upwelling studies (Geibert et al., 2002;Nozaki, 1984;Nozaki, 1993 So far, actinium has been mainly considered to behave in the ocean similarly to radium (Nozaki et al., 1990). Similar distribution coefficients of Ra and Ac in open ocean environments justify this assumption in many cases. However, actinium is expected to resemble the lanthanides in some aspects, like in its affinity for iron hydroxide, while radium is an alkaline earth metal that tends to be less particle reactive, but co-precipitates with Material and Methods Sampling and MeasurementOur data collection was produced with the radium delayed coincidence counting (RaDeCC) system (Moore and Arnold, 1996), which is routinely operated for the radiometrical determination of short-lived Ac data that was produced in different locations where short-lived Ra isotopes were measured (Figure 1). Sampling locations HawaiiTwo different types of samples were collected in the vicinity of Hawaii (Figure 4). A set of samples was taken in nearshore surface waters, at locations that are influenced by freshwater inputs to various degrees, as seen in the salinities of these samples. For a more detailed description of these sampling locations and the radium data, see ( Yucatan/ MexicoBrackish groundwater, lagoon water, and water from the shallow coastal ocean were Puerto RicoOff the north eastern coast of Puerto Rico, a number of Ac data from deep waters near the sea floor along the slope of the island are presented (Figure 6). In contrast to most other sites shown here, these sample locations are not influenced by release from the continental shelf or freshwater/groundwater mixing effects, but they are representing open ocean values in the vicinity of slope sediments. Israel, Gulf of AqabaSamples from the Israeli coast of the Red Sea near Elat ( Figur...

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Reply to ‘Challenging the hypothesis of an arctic ocean lake during recent glacial episodes’ by Hillaire‐Marcel, et al

Geibert

Matthießen

Wollenburg

et al. 2022

J Quaternary Science

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Hillaire-Marcel et al. bring forward several physical and geochemical arguments against our finding of an Arctic glaciolacustrine system in the past. In brief, we find that a physical approach to further test our hypothesis should additionally consider the actual bathymetry of the Greenland-Scotland Ridge (GSR), the density maximum of freshwater at 3-4°C, the sensible heat flux from rivers, and the actual volumes that are being mixed and advected. Their geochemical considerations acknowledge our original argument, but they also add a number of assumptions that are neither required to explain the observations, nor do they correspond to the lithology of the sediments. Rather than being additive in nature, their arguments of high particle flux, low particle flux, export of 230 Th and accumulation of 230 Th, are mutually exclusive. We first address the arguments above, before commenting on some misunderstandings of our original claim in their contribution, especially regarding our dating approach.

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The distribution of 230Th and 231Pa in the deep-sea surface sediments of the Pacific Ocean

Cited by 89 publications

References 25 publications

Transport and burial rates of10Be and231Pa in the Pacific Ocean during the Holocene period

Transport and burial rates of10Be and231Pa in the Pacific Ocean during the Holocene period

The release of dissolved actinium to the ocean: A global comparison of different end-members

Reply to ‘Challenging the hypothesis of an arctic ocean lake during recent glacial episodes’ by Hillaire‐Marcel, et al

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