Sökning: "Isotope"
Visar resultat 1 - 5 av 418 avhandlingar innehållade ordet Isotope.
1. Intramolecular isotope analysis reveals plant ecophysiological signals covering multiple timescales
Sammanfattning : 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. LÄS MER
2. Nitrogen Cycling at Cold Climate Mine Sites in Northen Sweden
Sammanfattning : 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. LÄS MER
3. Holocene climate and atmospheric circulation changes in northern Fennoscandia : Interpretations from lacustrine oxygen isotope records
Sammanfattning : 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). LÄS MER
4. Coping with environmental change : Lessons from isotope studies in a sentinel species
Sammanfattning : 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. LÄS MER
5. Origin of volcanic sulfur in Iceland : a sulfur isotope study
Sammanfattning : 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. LÄS MER