Sökning: "isotopic fractionation"

Visar resultat 1 - 5 av 9 uppsatser innehållade orden isotopic fractionation.

  1. 1. Investigating surface spring snow : Changes in the isotopic composition and conductivity along an orographic precipitation gradient in northern Fennoscandia

    Kandidat-uppsats, Umeå universitet/Institutionen för ekologi, miljö och geovetenskap

    Författare :Sara Andersson; [2023]
    Nyckelord :stable isotopes; snow; precipitation; hydrology; orography; earth science;

    Sammanfattning : Stable isotopes of oxygen (O18) and hydrogen (H2) are used as proxies of past climates when ice preserved in the polar icecaps. The main assumption when doing paleoclimatic reconstructions using these isotopes is that the isotopic composition of the snow that turned into ice reflect the present temperature of the planet during deposition. LÄS MER

  3. 2. The evaluation of preparation techniques for the measurements of hydrogen isotope ratios in ecology

    Master-uppsats, Umeå universitet/Institutionen för ekologi, miljö och geovetenskap

    Författare :Kusal Weragama; [2021]
    Nyckelord :Deuterium; liquid water equilibration; steam equilibration; exchangeable H fraction; non-exchangeable H; Equilibrium fractionation factor; Isotopic soil fraction;

    Sammanfattning : The stable isotope ratio of non-exchangeable hydrogen (δ2Hn) emerged as a promising new tool for source attribution in aquatic ecology, which can better discriminate between the organic matter sources. However, determining the absolute isotopic values is problematic due to the functional groups with hydrogen (H) that can easily exchange with the ambient water. LÄS MER

  4. 3. An annual evaluation of CH4 oxidation in a freshwater lake

    Kandidat-uppsats, Linköpings universitet/Tema Miljöförändring

    Författare :Eldina Cehic; [2020]
    Nyckelord :Methane oxidation; isotopic fractionation; stratification; open steady-state and closed system.; Metanoxidation; isotopfraktionering; stratifiering; öppet stabilt system och stängt system;

    Sammanfattning : Freshwater lakes constrain its methane (CH4) emissions through CH4 oxidation. CH4 includes three carbon (C) isotopes; the stable isotopes 12C,13C and the unstable and more uncommon isotope 14C. Methanotrophs (i.e. LÄS MER

  5. 4. Påverkar klimatförändringen trofisk fraktionering av C och N mellan växt och konsument i sötvattenekosystem?

    Kandidat-uppsats, SLU/Dept. of Aquatic Sciences and Assessment

    Författare :Evelina Hiltunen; [2018]
    Nyckelord :chironomus riparius; stable isotopes; trophic fractionation; climate change; oligotrophication;

    Sammanfattning : Temperaturhöjningen som en följd av klimatförändringen väntas gå fortast och bli störst på Nord- och Sydpolen. När lufttemperaturen stiger, stiger även vattentemperaturer och vegetationsgränser flyttas. Detta skulle kunna vara orsaken till den näringsutarmning som kan ses i många arktiska sjöar. LÄS MER

  7. 5. Peloponnesian Stalagmites and Soda Straw Stalactites as Climate Archives : Stable Isotopes in New Speleothem Material from Kapsia Cave, Peloponnese, Greece

    Kandidat-uppsats, Stockholms universitet/Institutionen för naturgeografi

    Författare :Linn Haking; [2017]
    Nyckelord :Stable Isotopes; Stalagmite; Soda Straw Stalactites; Climate Archive; Climate Variability; The Amount Effect; Isotopic Fractionation; Kapsia Cave; Peloponnese; Greece; Mediterranean;

    Sammanfattning : This study presents results from stable isotope analyses of a modern stalagmite and three soda straw stalactites from Kapsia Cave, the Peloponnese, Greece. The resulting values from the stalagmite are put into context of local meteorological data, as well as previous research from Kapsia Cave. LÄS MER