Repository of University of Nova Gorica

Search the repository
A+ | A- | Help | SLO | ENG

Query: search in
search in
search in
search in
* old and bolonia study programme

Options:
  Reset


1 - 1 / 1
First pagePrevious page1Next pageLast page
1.
Uranium isotope fractionation during adsorption, (co) precipitation, and biotic reduction
Douglas R. Evans, Bastian R. Georg, Wei Wang, Breda Novotnik, Duc Huy Dang, 2016, original scientific article

Abstract: Uranium contamination of surface environments is a problem associated with both U-ore extraction/processing and situations in which groundwater comes into contact with geological formations high in uranium. Apart from the environmental concerns about U contamination, its accumulation and isotope composition have been used in marine sediments as a paleoproxy of the Earth’s oxygenation history. Understanding U isotope geochemistry is then essential either to develop sustainable remediation procedures as well as for use in paleotracer applications. We report on parameters controlling U immobilization and U isotope fractionation by adsorption onto Mn/Fe oxides, precipitation with phosphate, and biotic reduction. The light U isotope (235U) is preferentially adsorbed on Mn/Fe oxides in an oxic system. When adsorbed onto Mn/Fe oxides, dissolved organic carbon and carbonate are the most efficient ligands limiting U binding resulting in slight differences in U isotope composition (δ238U = 0.22 ± 0.06‰) compared to the DOC/DIC-free configuration (δ238U = 0.39 ± 0.04‰). Uranium precipitation with phosphate does not induce isotope fractionation. In contrast, during U biotic reduction, the heavy U isotope (238U) is accumulated in reduced species (δ238U up to −1‰). The different trends of U isotope fractionation in oxic and anoxic environments makes its isotope composition a useful tracer for both environmental and paleogeochemical applications.
Found in: osebi
Keywords: Uranium, fractionation, biotic, abiotic, oxides
Published: 04.10.2019; Views: 182; Downloads: 0
.pdf Fulltext (4,30 MB)

Search done in 0 sec.
Back to top