Search for dissertations about: "isotope effects"

Showing result 1 - 5 of 115 swedish dissertations containing the words isotope effects.

2. 1. 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

4. 2. Isotopes as Mechanism Spies : Nucleophilic Bimolecular Substitution and Monoamine Oxidase B Catalysed Amine Oxidation Probed with Heavy Atom Kinetic Isotope Effects

   Author : Susanna MacMillar; Olle Matsson; Anita Hussénius; Daniel M. Quinn; Uppsala universitet; []
   Keywords : Organic chemistry; nucleophilic bimolecular substitution SN2; kinetic isotope effects; precision conductometry; monoamine oxidase B MAO B; reaction mechanism; carbon 11C 14C kinetic isotope effect; ion pairing triple-ion formation; para-substituted benzyl chlorides; tetrabytylammonium cyanide; Organisk kemi;

   Abstract : This thesis concerns the study of reaction mechanisms by means of kinetic isotope effects (KIEs). Studies of the nucleophilic bimolecular substitution (SN2) reaction had the dual purpose of improving our fundamental understanding of molecular reactivity and assessing the ability of kinetic isotope effects to serve as mechanistic tools. READ MORE

5. 3. Substituent and solvent effects on 1,3-hydron transfer in the indene system : a study of enantioselectivities, kinetic isotope effects, and catalyst conformations

   Author : Marie Aune; Uppsala universitet; []
   Keywords : NATURAL SCIENCES; NATURVETENSKAP;

   Abstract : .... READ MORE

6. 4. 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

7. 5. 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