Uranium in the oceans: Where it goes and why

Journal Article · Mon Jul 01 00:00:00 EDT 1991 · Geochimica et Cosmochimica Acta; (United States)

DOI:https://doi.org/10.1016/0016-7037(91)90024-Y· OSTI ID:5910393

Klinkhammer, G P ^[1]; Palmer, M R ^[2]

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1. Oregon State Univ., Corvallis (United States)
2. Bristol Univ. (England)

Uranium is removed from the oceans by diffusion across the sediment-water interface of organic-rich sediments. This pathway is the largest single sink in the global budget of this element. Dissolved uranium is drawn into suboxic sediments along a concentration gradient established by the precipitation of an insoluble phase which forms when U(VI) is reduced to U(IV). This transformation occurs relatively late in the diagenetic sequence, after the microbially mediated dissolution of manganese and iron oxides, and may be induced by the onset of sulfate reduction. Metallo-organics play an important role in the diagenetic behavior of this element as some uranium is released into solution when labile organics are consumed at the sediment-water interface. In contrast, the diagenesis of authigenic Fe- and Mn-oxides exerts negligible influence on the uranium diagenetic cycle. Variations in the uranium concentration of sediment with time are controlled directly by the uranium content of the source material settling from the water column, and indirectly, by the organic content of this material and sedimentation rate. Since diffusion from seawater influences dramatically the short-term burial rate of uranium, down-core distributions of dissolved and solid uranium can provide an estimate of recent sedimentation rates in rapidly accumulating sediments.

• OSTI ID: 5910393
• Journal Information: Geochimica et Cosmochimica Acta; (United States), Journal Name: Geochimica et Cosmochimica Acta; (United States) Vol. 55:7; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

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