Sökning: "stable isotopes"
Visar resultat 1 - 5 av 138 avhandlingar innehållade orden stable isotopes.
1. Fractionation of the stable silicon isotopes : analytical method developments and selected applications in geochemistry
Sammanfattning : During the last few decades, variations in the 'natural' isotopic abundances of stable elements (termed 'fractionation') have received considerable interest from the scientific community. Though analytical methods and techniques for the measurement of isotopic abundances with adequate figures of merit have been available for light elements (e.g. LÄS MER
2. Holocene climate and environmental change in high latitudes as recorded by stable isotopes in peat deposits
Sammanfattning : In this thesis, stable carbon and oxygen isotopes in α-cellulose isolated from Sphagnum fuscum moss remains were used as climate proxies. The main focus was to implement the methods in records from high latitude peatlands in the Northern Hemisphere (west-central Canada and north-eastern European Russia), reconstruct palaeoclimate of the studied regions during the Holocene, and evaluate the compatibility of results with other proxy records, especially tree-ring isotope time-series. LÄS MER
Sammanfattning : The main aim of this thesis is to show how scientific methods may be used to look at migration in prehistory on the basis of archaeological material. The individuals examined represent the period 4 000 BC to 1 000 AD and have their geographical origins in various parts of Sweden.Ancient DNA analysis is employed in three cases. LÄS MER
Sammanfattning : Increasing atmospheric reactive nitrogen (Nr), as consequence of human activities, has generated accumulation of nitrate (NO3-) in Arctic regions. The Arctic has fragile nitrogen limited ecosystems that can be altered by increases of dry or wet deposition of Nr. LÄS MER
5. Terrestrial organic carbon dynamics in Arctic coastal areas : budgets and multiple stable isotope approaches
Sammanfattning : Arctic rivers transport 31-42 Tg organic carbon (OC) each year to the Arctic Ocean, which is equal to 10% of the global riverine OC discharge. Since the Arctic Ocean only holds approximately 1% of the global ocean volume, the influence of terrestrially derived organic carbon (OCter) in the Arctic Ocean is relatively high. LÄS MER