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1.
Variations in U concentrations and isotope signatures in two Canadian lakes impacted by U mining: A combination of anthropogenic and biogeochemical processes
Wei Wang, Duc Huy Dang, Breda Novotnik, R. Douglas Evans, Thai T. Phan, 2019, izvirni znanstveni članek

Opis: Temporal and vertical variations in uranium (U) concentrations and U isotope (δ238U, ‰) signatures were examined in sediment cores collected seven times over a one year period, from two lakes in Ontario, Canada, which are contaminated with U by historical mining activities. Bow Lake is holomictic, experiencing seasonal anoxia, while the sediments of meromictic Bentley Lake are permanently anoxic. Average annual peak concentrations of U in Bow Lake subsurface sediments were approximately 300 μg L−1 and 600 μg g−1 in porewater and bulk sediments, respectively. Similar ranges of concentrations (900 μg L−1 and 600 μg g−1, respectively) were observed in Bentley Lake sediments. The exceedingly high levels of U observed in the porewaters of both lakes, as well as the seasonal variability in U levels, challenge the traditional paradigm regarding U chemistry, i.e., that reduced U(IV) should be insoluble under anoxic conditions. The average annual δ238U ‰ values at the sediment-water interface of both lakes were similar (i.e., 0.47 ± 0.09‰ and 0.50 ± 0.16‰, relative to IRMM-184). The deep sediments in both Bentley Lake and Bow Lake record U isotope composition with a typical fractionation of 0.6‰ relative to the surface water, confirming authigenic U accumulation, i.e., negligible contribution of particulate material from the tailings. Also, the δ238U values in porewater have an average offset of ca. −0.1‰ relative to bulk sediments in anoxic zones and are reversed in the oxic sediment layer.
Ključne besede: Uranium Isotope composition Uranium tailings Biogeochemical cycling Redox chemistry
Objavljeno: 09.10.2019; Ogledov: 25; Prenosov: 0
.pdf Polno besedilo (3,89 MB)

2.
Uranium bearing dissolved organic matter in the porewaters of uranium contaminated lake sediments
Breda Novotnik, Wei Chen, R. Douglas Evans, 2018, izvirni znanstveni članek

Opis: 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.
Ključne besede: Uranium Lake sediments Porewater Disolved organic matter High resolution mass spectrometry
Objavljeno: 09.10.2019; Ogledov: 25; Prenosov: 0
.pdf Polno besedilo (1,48 MB)

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Digital Humanities and Fine Arts Studies at the University of Nova Gorica
Aleš Vaupotič, prispevek na konferenci brez natisa

Opis: In the occasion of release of the book about manifestation Real Presence will be held between 3rd and 8th of October series of events, including talks, presentations, performances, workshops and exhibitions in which will take part international and Serbian artists. Friday, 4.10.2019 - 3 - 6 pm - in the Belgrade City Library, Knez Mihailova Street 56 - Present Academy symposium. Participants: Alberto Gianfreda, Associate Professor, Brera Academy, Milan; Alessandra Saviotti, PhD candidate - Liverpool John Moores University & Tutor - ArtEZ University of the Arts, Arnhem; Christian Sievers, Associate Professor, Academy of Media Arts Cologne; Nemanja Nikolić, Assistant Professor, Faculty of Fine Arts, Belgrade, Saša Tkačenko, Assistant Professor, Faculty of Architecture, Novi Sad, Aleš Vaupotič, acting head of the Research Centre for Humanities / University of Nova Gorica; Narvika Bovcon, Associate Professor, Faculty of Computer and Information Science / University of Ljubljana; Milenko Prvački, Senior Fellow - Office of the President - LASALLE College of the Arts - Faculty of Fine Arts; Jacob Tonski, Associate Professor, School of the Art Institute of Chicago. The book: https://issuu.com/maximilianmauracher/docs/realpresence_2019_2
Ključne besede: digital humanities, art, science, pedagogy
Objavljeno: 08.10.2019; Ogledov: 63; Prenosov: 0
.pdf Polno besedilo (118,46 KB)

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Bralnomotivacijske strategije pri pouku španščine
strokovna monografija

Opis: Strokovna monografija (tipologije ni mogoče dodati).
Ključne besede: bralnomotivacijske strategije, poučevanje, literatura pri pouku tujega jezika, španščina
Objavljeno: 07.10.2019; Ogledov: 450; Prenosov: 0
.pdf Polno besedilo (332,10 KB)

6.
Še o slovenski književni krajini
Barbara Pregelj, 2019, strokovni članek

Opis: Avtorica pregleduje slovensko književno krajino in jo primerja s špansko, baskovsko, katalonsko in galicijsko, pri čemer še posebej izpostavi pomen manjših slovenskih založb.
Ključne besede: književna krajina, založništvo, knjižni trg, majhne založbe, primerjave
Objavljeno: 07.10.2019; Ogledov: 38; Prenosov: 0
.pdf Polno besedilo (179,35 KB)

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Bralnomotivacijske strategije in uživanje v branju
Barbara Pregelj, druga izvedena dela

Ključne besede: bralna motivacija, strategije, užitek, branje
Objavljeno: 07.10.2019; Ogledov: 47; Prenosov: 0
.pdf Polno besedilo (497,48 KB)

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Uranium isotope fractionation during adsorption, (co) precipitation, and biotic reduction
Douglas R. Evans, Bastian R. Georg, Wei Wang, Breda Novotnik, Duc Huy Dang, 2016, izvirni znanstveni članek

Opis: 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.
Ključne besede: Uranium, fractionation, biotic, abiotic, oxides
Objavljeno: 04.10.2019; Ogledov: 61; Prenosov: 0
.pdf Polno besedilo (4,30 MB)

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