Sökning: "Christophe Dupraz"

Hittade 3 avhandlingar innehållade orden Christophe Dupraz.

  1. 1. Phosphate and Arsenic Cycling under Experimental Early Proterozoic Marine Conditions

    Författare :Christoffer Hemmingsson; Iain Pitcairn; Ernest Chi Fru; Per Andersson; Christophe Dupraz; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; DIP; Early Proterozoic; coprecipitation; adsorption; Iron formations; BIF; geokemi; Geochemistry;

    Sammanfattning : Nutrient dynamics in the Archean-Paleoproterozoic oceans strongly influenced primary productivity and the rise of atmospheric O2. Reconstructing the cycling of key nutrients such as dissolved inorganic phosphate (DIP) at this time is important for our understanding of the timing, rate and extent of atmospheric oxygenation at this time. LÄS MER

  3. 2. Microbially mediated formation of birnessite-type manganese oxides and subsequent incorporation of rare earth elements, Ytterby mine, Sweden

    Författare :Susanne Sjöberg; Christophe Dupraz; Rienk Smittenberg; Volker Brüchert; Helena Filipsson; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; microbial diversity; manganese oxides; birnessite; rare earth elements; subterranean; Ytterby mine; geokemi; Geochemistry;

    Sammanfattning : Microbes exert extensive control on redox element cycles. They participate directly orindirectly in the concentration and fractionation of elements by influencing the partitioningbetween soluble and insoluble species. LÄS MER

  4. 3. Microbially mediated manganese oxides enriched in yttrium and rare earth elements in the Ytterby mine, Sweden

    Författare :Susanne Sjöberg; Christophe Dupraz; Per Persson; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; manganese oxidizers; birnessite; yttrium and rare earth elements YREE ; biofilms; shallow subsurface; Ytterby mine; geomicrobiology; microbial geochemistry; manganoxiderare; birnessit; yttrium och sällsynta jordartsmetaller YREE ; underjordisk; Ytterby mine; geomikrobiologi; mikrobiell kemi; geokemi; Geochemistry;

    Sammanfattning : Microorganisms are able to manipulate redox reactions and thus exert extensive control on chemical speciation and element partitioning in nature, affecting the formation and dissolution of certain minerals. One of these redox active elements is manganese (Mn), which in its oxidized states (III/IV), commonly forms Mn oxide-hydroxide minerals. LÄS MER