Lead-210 and polonium-210 in ocean water profiles of the continental shelf and slope south of New England

Bacon, Michael P.; Belastock, Rebecca A.; Tecotzky, Mark; Turekian, Karl K.; Spencer, Derek W.

doi:10.1016/0278-4343(88)90079-9

Cited by 91 publications

(42 citation statements)

References 16 publications

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“…The 210 Pb t / 226 Ra ratio showed a decreasing trend toward sediments in the bottom layer, indicating intensified scavenging at the water-sediment interface (Spencer et al, 1980). This boundary-scavenging phenomenon was also reported in the North Pacific (Nozaki et al, 1980), the Indian Ocean (Cochran et al, 1983), and the continental slope of the South Atlantic Bight (Bacon et al, 1988). Vertical profiles of the 210 Po t / 210 Pb t ratio of the four cruises to the SEATS station are shown in Fig.…”

Section: Pb / 226 Ra and 210 Po / 210 Pb Disequilibriasupporting

confidence: 79%

“…Recent results of an inter-calibration project also showed a significant deficiency of 210 Po relative to 210 Pb in the deep water, with a 210 Po / 210 Pb ratio of 0.74 ± 0.06 at 2000 m at BATS in the North Atlantic and 0.80 ± 0.11 at 3000 m at the baseline station in the North Pacific, respectively (Church et al, 2012). It should be noted that, contrary to the 210 Po deficiencies in these environments, the 210 Po t / 210 Pb t ratio is commonly close to unity in the deep layer (> 1000 m) of the ocean (Bacon et al, 1976(Bacon et al, , 1988Cochran et al, 1983;Nozaki et al, 1997).…”

Section: Pb / 226 Ra and 210 Po / 210 Pb Disequilibriamentioning

confidence: 89%

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Seasonal distributions and fluxes of 210Pb and 210Po in the northern South China Sea

Wei

Lin

et al. 2014

Biogeosciences

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Abstract. Vertical distributions of dissolved and particulate 210 Pb and 210 Po in the water column at the SouthEast Asian Time-series Study (SEATS, 18 • 00 N and 116 • 00 E) station in the northern South China Sea were determined from four cruises between January 2007 and June 2008. A large deficiency of 210 Pb, 379 ± 43 × 10 3 dpm m −2 , from the secular equilibrium was found within the 3500 m water column. On the other hand, a smaller deficiency of 210 Po, 100 ± 21 × 10 3 dpm m −2 , relative to 210 Pb was found in the water column. Time-series data showed insignificant temporal variability of the 210 Pb and 210 Po profiles. To balance these deficiencies, the removal fluxes for 210 Pb and 210 Po via particle settling ranging from 45 to 51 dpm m −2 d −1 and from 481 to 567 dpm m −2 d −1 , respectively, are expected at 3500 m. The 210 Pb removal flux is comparable with, whereas the 210 Po removal flux is much higher than, the flux directly measured by moored sediment traps. The discrepancy between the modeled 210 Po flux and the measured flux suggests that sporadic events that enhance 210 Po removal via sinking ballast may occur in the water column at the site.

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Section: Pb / 226 Ra and 210 Po / 210 Pb Disequilibriasupporting

confidence: 79%

Section: Pb / 226 Ra and 210 Po / 210 Pb Disequilibriamentioning

confidence: 89%

Seasonal distributions and fluxes of 210Pb and 210Po in the northern South China Sea

Wei

Lin

et al. 2014

Biogeosciences

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“…It is noteworthy that a log K d of about 8 is higher than that of the overall K d of~7 for natural particles in the ocean (e.g., Bacon et al, 1988;Guo et al, 1995Murray et al, 2005).…”

Section: This Issue and References Therein)mentioning

confidence: 89%

Thorium speciation in seawater

et al. 2006

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Since the 1960s, thorium isotopes occupy a special place in the oceanographer's toolbox as tracers for determining rates and mechanisms of oceanic scavenging, particle dynamics, and carbon fluxes. Due to their unique and constant production rates from soluble parent nuclides of uranium and radium, their disequilibrium can be used to calculate rates and time scales of sinking particles. In addition, by ratio-ing particulate 234 Th (as well, in principle, other Th-nuclides) to carbon (and other elements), and linking this ratio to the parent-daughter disequilibrium in the water column, it is possible to calculate fluxes of carbon and other elements. Most of these applications are possible with little knowledge of the dissolved chemical properties of thorium, other than its oxidation state (IV) and tendency to strongly sorb to surfaces, i.e., its bparticle-or surface-activityQ. However, the use of any tracer is hindered by a lack of knowledge of its chemical properties. Recent observations in the variability of carbon to 234 Th ratios in different particle types, as well as of associations of Th(IV) with various marine organic biomolecules has led to the need for a review of current knowledge and what future endeavors should be taken to understand the marine chemistry of thorium. D

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“…It has been also noted by Bacon et al (1988) that a strong 210Pb concen tration gradient exists in the shelf-edge zone. In the East China Sea, the concentrations of 210Pb in surface water deceased by a factor of 5-10 from the Kuroshio to the shelf (Nozaki et al, 1990b), while the concentrations of 226Ra increas ed by a factor of two .…”

Section: Resultsmentioning

confidence: 83%

Lateral transport of sediment particles in the Okinawa Trough determined by natural radionuclides.

1990

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Settling particles at 640 m, 1390 m, and 1920 m depths in the Okinawa Trough and bottom sediments at six sites in the East China Sea were analyzed for U and Th isotopes, 210Pb, and 210Po. Con centrations of 212Th in the settling particles were higher than those observed in the open ocean and were relatively constant with depth compared with other radiogenic nuclides. Fluxes and concentrations of these radiogenic nuclides increased with depth and the measured fluxes were larger than those calculated from water column inventories. While sinking through the water column of 640-1390 m, the increases in 210Pb and unsupported 228Th fluxes originating intensively in the shelf region were much larger than the unsupported 230Th fluxes produced evenly in sea water. The 210Po/210Pb activity ratio in the settling par ticles was almost unity and the 2uTh/230Th activity ratio of the radiogenic fraction was much smaller than the ratio of the production rates of these nuclides in the shelf water. These results suggest that a large fraction of the deeper settling particles, as well as the sediments in the trough zone originating in the continental shelf zone, are transported laterally and downward via the near bottom layer on a time scale of approximately 16 years on the average.

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Lead-210 and polonium-210 in ocean water profiles of the continental shelf and slope south of New England

Cited by 91 publications

References 16 publications

Seasonal distributions and fluxes of <sup>210</sup>Pb and <sup>210</sup>Po in the northern South China Sea

Seasonal distributions and fluxes of <sup>210</sup>Pb and <sup>210</sup>Po in the northern South China Sea

Thorium speciation in seawater

Lateral transport of sediment particles in the Okinawa Trough determined by natural radionuclides.

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Lead-210 and polonium-210 in ocean water profiles of the continental shelf and slope south of New England

Cited by 91 publications

References 16 publications

Seasonal distributions and fluxes of &lt;sup&gt;210&lt;/sup&gt;Pb and &lt;sup&gt;210&lt;/sup&gt;Po in the northern South China Sea

Seasonal distributions and fluxes of &lt;sup&gt;210&lt;/sup&gt;Pb and &lt;sup&gt;210&lt;/sup&gt;Po in the northern South China Sea

Thorium speciation in seawater

Lateral transport of sediment particles in the Okinawa Trough determined by natural radionuclides.

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Product

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Seasonal distributions and fluxes of <sup>210</sup>Pb and <sup>210</sup>Po in the northern South China Sea

Seasonal distributions and fluxes of <sup>210</sup>Pb and <sup>210</sup>Po in the northern South China Sea