Sökning: "stable isotopes"

Visar resultat 1 - 5 av 138 avhandlingar innehållade orden stable isotopes.

  1. 1. Fractionation of the stable silicon isotopes : analytical method developments and selected applications in geochemistry

    Författare :Emma Engström; Luleå tekniska universitet; []

    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. 2. Holocene climate and environmental change in high latitudes as recorded by stable isotopes in peat deposits

    Författare :Päivi Kaislahti Tillman; Steffen Holzkämper; Stefan Wastegård; Peter Kuhry; Thomas W. D. Edwards; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; stable isotopes; Holocene; subarctic; climate; Sphagnum fuscum; Quarternary Geology; kvartärgeologi;

    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

  3. 3. Migration in Prehistory : DNA and stable isotope analyses of Swedish skeletal material

    Författare :Anna Linderholm; Kerstin Lidén; Oliver Craig; Stockholms universitet; []
    Nyckelord :HUMANITIES; HUMANIORA; HUMANIORA; HUMANITIES; Migration; ancient DNA; stable isotopes; δ13C; δ15N; δ34S; mtDNA; lactose tolerance; Neolithic; Pitted Ware culture; Funnel Beaker culture; Vikings; Öland; Rössberga; Birka; Björned; Archaeology; Arkeologi; Archaeological Science; laborativ arkeologi;

    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

  4. 4. Nitrate stable isotopes and major ions in snow and ice from Svalbard

    Författare :Carmen Paulina Vega Riquelme; V. A. Pohjola; R. Pettersson; E. Isaksson; C. E. Bøggild; Kumiko Goto-Azuma; Uppsala universitet; []
    Nyckelord :nitrate stable isotopes; nitrate; NOx proxies; ice cores; percolation; ion relocation; Svalbard; stabila isotoper av nitrat; nitrat; indikator för kväveoxider; iskärnor; perkolation; joniska omlokalisering; Svalbard; Earth Science with specialization in Physical Geography; Geovetenskap med inriktning mot naturgeografi;

    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. 5. Terrestrial organic carbon dynamics in Arctic coastal areas : budgets and multiple stable isotope approaches

    Författare :Vanja Alling; Christoph Humborg; Carl-Magnus Mörth; Rüdiger Stein; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; organic carbon; DOC; POC; multiple stable isotopes; Laptev Sea; East Siberian Sea; Lena River; Arctic; residence times; degradation; Applied Environmental Science; tillämpad miljövetenskap;

    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