Search for dissertations about: "Isotope"

Showing result 1 - 5 of 415 swedish dissertations containing the word Isotope.

  2. 1. Intramolecular isotope analysis reveals plant ecophysiological signals covering multiple timescales

    Author : Thomas Wieloch; Jürgen Schleucher; Mats Nilsson; Gerd Gleixner; Lisa Wingate; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NMR spectroscopy; tree ring; isotope ratio; isotope effect; intramolecular 13C 12C signal; carbon allocation; acclimation; plant performance; climate reconstruction; plant ecophysiology;

    Abstract : Our societies' wellbeing relies on stable and healthy environments. However, our current lifestyles, growth-oriented economic policies and the population explosion are leading to potentially catastrophic degradation of ecosystems and progressive disruption of food chains. READ MORE

  4. 2. Nitrogen Cycling at Cold Climate Mine Sites in Northen Sweden

    Author : Lino Nilsson; Anders Widerlund; Anders Lundqvist; Luleå tekniska universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Nitrogen; Mining; Cycling; nutrients; Isotopes; Nitrogen-model; modelling; numerical-modelling; Isotope-tracing; Tracing; Isotope; geochemistry; Applied Geology; Tillämpad geologi;

    Abstract : High nitrogen discharge from mining sites has been an environmental issue that has been closely studied in the recent years. The environmental effects of high nitrogen discharge are mainly eutrophication, but can also lead to changed species composition and algae blooms. READ MORE

  5. 3. Holocene climate and atmospheric circulation changes in northern Fennoscandia : Interpretations from lacustrine oxygen isotope records

    Author : Christina E. Jonsson; Gunhild Rosqvist; Jan Seibert; Philip Barker; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; oxygen isotope; diatom silica; lake sediment; atmospheric circulation; North Atlantic Oscillation; northern Fennoscandia; The Holocene; Little Ice Age; Physical geography; Naturgeografi; Physical Geography; naturgeografi;

    Abstract : This thesis investigates how variations in the oxygen isotopic composition of lake waters in northern Fennoscandia are recorded in lake sediment archives, especially diatoms, and how these variations can be used to infer past changes in climate and atmospheric circulation. Results from analyses of the oxygen isotopic composition of lake water samples (δ18Olakew) collected between 2001 and 2006 show that δ18O of northern Fennoscandian lakes is mainly controlled by the isotopic composition of the precipitation (δ18Op). READ MORE

  6. 4. Coping with environmental change : Lessons from isotope studies in a sentinel species

    Author : Matias Ledesma; Agnes Karlson; Marleen De Troch; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; stable isotope; compound-specific nitrogen stable isotope analysis; trophic niche; harmful algae blooms; contaminants; stress; reproductive success; environmental change; Baltic Sea; marin ekologi; Marine Ecology;

    Abstract : Adaptive evolution and phenotypic plasticity are two key mechanisms by which natural populations avoid extinction in the face of environmental change. Evolutionary young systems, such as the Baltic Sea with low species diversity and steep environmental gradients, are good models for studying how wild populations cope with environmental changes, such as climate-induced alterations in food supply and exposure to environmental contaminants. READ MORE

  7. 5. Origin of volcanic sulfur in Iceland : a sulfur isotope study

    Author : Peter Torssander; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES;

    Abstract : The chemistry and sulfur isotope composition have been determined in fresh and altered rocks and geothermal fluids in Iceland. Sulfur isotope ratios were analysed in 27 selected volcanic rocks, eight lava incrustations and three volcanic gas samples.The 63% of the basalts ranges from -2.0 o/oo to + 0. READ MORE