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Title:Uranium bearing dissolved organic matter in the porewaters of uranium contaminated lake sediments
Authors:Novotnik, Breda (Author)
Chen, Wei (Author)
Evans, R. Douglas (Author)
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Work type:Not categorized (r6)
Tipology:1.01 - Original Scientific Article
Organization:UNG - University of Nova Gorica
Abstract:Uranium (U) mobility in the environment strongly depends on its oxidation state and the presence of complexing agents such as inorganic carbon, phosphates, and dissolved organic matter (DOM). Despite the importance of DOM in U mobility, the exact mechanism is still poorly understood. Therefore, the aim of our investigation was to characterise sediment porewater DOM in two lakes in Ontario, Canada (Bow and Bentley Lakes) that were historically contaminated with U and propose possible composition of UO2-bearing DOM. Depth profiles of U concentrations in porewaters and total sediment digests reveal U levels of up to 1.3 mg L−1 in porewater and up to 0.8 mg−1 g in sediment. Depth profiles of U did not correlate with Fe, Mn, SO4 2−, or Eh profiles. Therefore, porewater DOM was analysed and taken into consideration as the primary source of U mobility. Porewater DOM in each sediment section (1 cm sections, 20 cm core length) was analysed by high-resolution electrospray ionisation mass spectrometry. PCA analyses of porewater DOM mass spectra showed grouping and clear separation of DOM in sediment sections with elevated U concentrations in comparison to sections with background U concentrations. Several criteria were set to characterise UO2-bearing DOM and more than 70 different molecules were found. The vast majority of these UO2-DOM compounds fell in the category of carboxyl-containing aliphatic molecules (H/C between 0.85 and 1.2 and O/C≤0.4) and had a mean value of m/z about 720.
Keywords:Uranium Lake sediments Porewater Disolved organic matter High resolution mass spectrometry
Year of publishing:2018
Number of pages:36-44
Numbering:91, 2018
COBISS_ID:5460731 Link is opened in a new window
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Record is a part of a journal

Title:Applied Geochemistry
Year of publishing:2018