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* old and bolonia study programme


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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, 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: ključnih besedah
Summary of found: ...Uranium, fractionation, biotic, abiotic, oxides...
Keywords: Uranium, fractionation, biotic, abiotic, oxides
Published: 04.10.2019; Views: 489; Downloads: 0
.pdf Fulltext (4,30 MB)

Impact of high or low levels of phosphorus and high sodium in soils on productivity and stress tolerance of Arundo donax plants
Claudia Cocozza, Federico Brilli, Laura Miozzi, Sara Pignattelli, Silvia Rotunno, Cecilia Brunetti, Cristiana Giordano, Susanna Pollastri, Mauro Centritto, Gian Paolo Accotto, Roberto Tognetti, Francesco Loreto, 2019, original scientific article

Abstract: The potential of Arundo donax to grow in degraded soils, characterized by excess of salinity (Na+), and phosphorus deficiency (-P) or excess (+P) also coupled with salinity (+NaP), was investigated by combining in vivo plant phenotyping, quantification of metabolites and ultrastructural imaging of leaves with a transcriptome-wide screening. Photosynthesis and growth were impaired by+Na, -P and+NaP. While+Na caused stomatal closure, enhanced biosynthesis of carotenoids, sucrose and isoprene and impaired anatomy of cell walls, +P negatively affected starch production and isoprene emission, and damaged chloroplasts. Finally, +NaP largely inhibited photosynthesis due to stomatal limitations, increased sugar content, induced/repressed a number of genes 10 time higher with respect to+P and+Na, and caused appearance of numerous and large plastoglobules and starch granules in chloroplasts. Our results show that A. donax is sensitive to unbalances of soil ion content, despite activation of defensive mechanisms that enhance plant resilience, growth and biomass production of A. donax under these conditions.
Found in: ključnih besedah
Summary of found: ... Abiotic stress Giant reed Isoprene emission Phosphorus Salinity Transcriptome...
Keywords: Abiotic stress Giant reed Isoprene emission Phosphorus Salinity Transcriptome
Published: 20.04.2020; Views: 249; Downloads: 0
.pdf Fulltext (10,07 MB)

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