Concentration, oxidation state, and particulate flux of uranium in the Black Sea

Anderson, Robert F.; Fleisher, Martin Q.; LeHuray, A. P.

doi:10.1016/0016-7037(89)90345-1

Cited by 307 publications

(119 citation statements)

References 30 publications

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“…Several researchers have studied U removal in nature at locations such as the Black Sea (Anderson et al, 1989b), the Pacific Ocean near Vancouver/Canada (Anderson et al, 1989a), and in a fjord off the coast of Norway (Swarzenski et al, 1999). All researchers suggest that natural U carbonates become associated with certain natural organic matter such as diatoms and that these diatoms, when dead, sink to the ocean floor, carrying U with them.…”

Section: Stage 2: Sedimentationmentioning

confidence: 99%

The removal of uranium from mining waste water using algal/microbial biomass

Kalin¹,

Wheeler²,

Meinrath³

2005

Journal of Environmental Radioactivity

304

134

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We describe a three step process for the removal of uranium (U) from dilute waste waters.Step one involves the sequestration of U on, in, and around aquatic plants such as algae. Cell wall ligands efficiently remove U(VI) from waste water. Growing algae continuously renew the cellular surface area.Step 2 is the removal of U-algal particulates from the water column to the sediments.Step 3 involves reducing U(VI) to U(IV) and transforming the ions into stable precipitates in the sediments. The algal cells provide organic carbon and other nutrients to heterotrophic microbial consortia to maintain the low E H , within which the U is transformed.Among the microorganisms, algae are of predominant interest for the ecological engineer because of their ability to sequester U and because some algae can live under many extreme environments, often in abundance. Algae grow in a wide spectrum of water qualities, from alkaline environments (Chara, Nitella) to acidic mine drainage waste waters (Mougeotia, Ulothrix). If they could be induced to grow in waste waters, they would provide a simple, longterm means to remove U and other radionuclides from U mining effluents. This paper reviews the literature on algal and microbial adsorption, reduction, and transformation of U in waste streams, wetlands, lakes and oceans.

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Section: Stage 2: Sedimentationmentioning

confidence: 99%

The removal of uranium from mining waste water using algal/microbial biomass

Kalin¹,

Wheeler²,

Meinrath³

2005

Journal of Environmental Radioactivity

304

134

View full text Add to dashboard Cite

show abstract

“…But non conservative U behavior has also been reported in a wide range of oceanic regions ( Figure 7). This may be due to U precipitation and removal in suboxic or anoxic marine basins, such as the Black Sea (Anderson et al 1989), the Baltic Sea (Löfvendahl 1987), the Arabian Sea (Rengarajan et al 2003) or North-European fjords (Todd et al 1988). …”

Section: U-salinity Relationshipmentioning

confidence: 99%

A review of present techniques and methodological advances in analyzing 234Th in aquatic systems

et al. 2006

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The short-lived thorium isotope 234 Th (half-life 24.1 days) has been used as a tracer for a variety of transport processes in aquatic systems. Its use as a tracer of oceanic export via sinking particles has stimulated a rapidly increasing number of studies that require analyses of 234 Th in both marine and freshwater systems. The original 234 Th method is labour intensive.Thus, there has been a quest for simpler techniques that require smaller sample volumes.Here, we review current methodologies in the collection and analysis of 234 Th from the water column, discuss their individual strengths and weaknesses, and provide an outlook on possible further improvements and future challenges. Also included in this review are recommendations on calibration procedures and the production of standard reference materials as well as a flow chart designed to help researchers find the most appropriate 234 Th analytical technique for a specific aquatic regime and known sampling constraints.

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“…U concentrations and the U/Th ratios in sedimentary rocks have been widely used as paleoredox proxies (Anderson et al, 1989;Moford and Emerson, 1999;Wignall and Twitchett, 1996). Under oxic conditions, U exists as soluble U(VI) in the form of uranyl carbonate complexes (Langmuir, 1978).…”

mentioning

confidence: 99%

Uranium isotope fractionation during coprecipitation with aragonite and calcite

Chen

Romaniello

Herrmann

et al. 2016

Geochimica et Cosmochimica Acta

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Natural variations in 238 U/ 235 U of marine carbonates might provide a useful way of constraining redox conditions of ancient environments. In order to evaluate the reliability of this proxy, we conducted aragonite and calcite coprecipitation experiments at pH ~7.5 and ~ 8.5 to study possible U isotope fractionation during incorporation into these minerals.Small but significant U isotope fractionation was observed in aragonite experiments at pH ~ 8.5, with heavier U in the solid phase. 238 U/ 235 U of dissolved U in these experiments can be fit by Rayleigh fractionation curves with fractionation factors of 1.00007+0.00002/-0.00003, 1.00005 ± 0.00001, and 1.00003 ± 0.00001. In contrast, no resolvable U isotope fractionation was observed in an aragonite experiment at pH ~7.5 or in calcite experiments at either pH. Equilibrium isotope fractionation among different aqueous U species is the most likely explanation for these findings. Certain charged U species are preferentially incorporated into calcium carbonate relative to the uncharged U species Ca 2 UO 2 (CO 3 ) 3 (aq), which we hypothesize has a lighter equilibrium U isotope composition than most of the charged species. According to this hypothesis, the magnitude of U isotope fractionation should scale with the fraction of dissolved U that is present as Ca 2 UO 2 (CO 3 ) 3 (aq). This expectation is confirmed by equilibrium speciation modeling of our experiments. Theoretical calculation of the U isotope fractionation factors between different U species could further test this hypothesis and our proposed fractionation mechanism.ii These findings suggest that U isotope variations in ancient carbonates could be controlled by changes in the aqueous speciation of seawater U, particularly changes in seawater pH, P CO2 , [Ca], or [Mg] concentrations. In general, these effects are likely to be small (<0.13 ‰), but are nevertheless potentially significant because of the small natural range of variation of 238 U/ 235 U.

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Concentration, oxidation state, and particulate flux of uranium in the Black Sea

Cited by 307 publications

References 30 publications

The removal of uranium from mining waste water using algal/microbial biomass

The removal of uranium from mining waste water using algal/microbial biomass

A review of present techniques and methodological advances in analyzing 234Th in aquatic systems

Uranium isotope fractionation during coprecipitation with aragonite and calcite

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