Sökning: "naturgeografi"
Visar resultat 6 - 10 av 341 avhandlingar innehållade ordet naturgeografi.
6. 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
7. Late Quaternary climate and environmental change in the summer rainfall region of South Africa : A study using trees and wetland peat cores as natural archives
Sammanfattning : This thesis contributes with information on past climate and environmental changes in South Africa’s summer rainfall region. The study is based on multi-proxy analyses on wetland peat cores and analyses of stable isotope composition (δ13C, δ18O) and wood anatomy in cross sections from subtropical trees (Breonadia salicina). LÄS MER
8. Waterborne sediment and pollutant transport into lakes and accumulation in lake sediments
Sammanfattning : The general objective of this thesis is to contribute to the knowledge of the transport of sediments and pollutants from catchments to downstream water recipient systems and their accumulation in these systems, such as lakes and lake sediments. One part of the thesis studies the importance of drainage reach morphology and water flow for the phosphorous (P) transport and retention in the reaches, and the main controlling processes of the P retention in the reach sediments. LÄS MER
9. Modelling water and solute flows at land-sea and land-atmosphere interfaces under data limitations
Sammanfattning : Water and vapour flows from land to sea and the atmosphere are important for water resources, coastal ecosystems and climate. This thesis investigates possible methods for modelling these flows under often encountered unmonitored hydrological conditions and data limitations. LÄS MER
10. Regulation of carbon dioxide emission from Swedish boreal lakes and the Gulf of Bothnia
Sammanfattning : The global carbon cycle is subject to intense research, where sources and sinks for greenhouse gases, carbon dioxide in particular, are estimated for various systems and biomes. Lakes have previously been neglected in carbon balance estimations, but have recently been recognized to be significant net sources of CO2. LÄS MER