Sökning: "earth"

Visar resultat 21 - 25 av 3321 avhandlingar innehållade ordet earth.

1. 21. Agpaitic Rocks of the Norra Kärr Alkaline Complex: Chemistry, Origin, and Age of Eudialyte-hosted Zirconium and Rare-earth Element Ore

   Författare :Axel S.L. Sjöqvist; Göteborgs universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Norra Kärr alkaline complex; agpaitic rocks; eudialyte; rare-earth elements; geochronology; radiogenic isotope geochemistry;

   Sammanfattning : Agpaites are peralkaline nepheline syenites that are denominated by rock-forming complex silicate minerals such as eudialyte. The exotic mineralogy and chemistry of these rocks are not only interesting for research, but globally these rocks also have potential as polymetallic resources of elements such as zirconium, niobium, rare-earth elements, zinc, and uranium. LÄS MER

3. 22. Validation and time series analysis of global stratospheric data sets

   Författare :Ashley Jones; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; OSIRIS; MIPAS; remote sensing; data assimilation; Trend; stratosphere; ozone; linear regression; Odin; validation;

   Sammanfattning : The depletion of ozone from the stratosphere and the impact of global warming have been identified as phenomena caused as a result of anthropogenic activity. Scientists are thus trying to find quicker and more reliable ways to analyse these environmental problems. LÄS MER

4. 23. Primary Production in African Drylands : Quantifying Supply and Demand Using Earth Observation and Socio-ecological Data

   Författare :Abdulhakim Abdi; Institutionen för naturgeografi och ekosystemvetenskap; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Net primary production; Africa; Drylands; Coupled human and natural systems; Human-Environment Relations; Food security; Earth observation; Remote Sensing;

   Sammanfattning : The human-environment connection in the mostly rural drylands of sub-Saharan Africa forms a complex, interlinked system that provides ecosystem services. This system is susceptible to climatic variability that impacts the supply of its products, and high population growth, which impacts the demand for these products. LÄS MER

5. 24. Quaternary paleoceanography of the Arctic Ocean : A study of sediment stratigraphy and physical properties

   Författare :Emma Sellén; Martin Jakobsson; Jan Backman; Dorthe Klitgaard-Kristensen; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Arctic Ocean; sedimentology; Quaternary; stratigraphy; physical properties; Earth sciences; Geovetenskap; Quaternary geology; Kvartärgeologi; Sedimentology; Sedimentologi; Marine Geoscience; marin geovetenskap;

   Sammanfattning : A Quaternary perspective on the paleoceanographic evolution of the central Arctic Ocean has been obtained in this PhD thesis by studying sediment cores from all of the Arctic’s major submarine ridges and plateaus. The included cores were mainly recovered during the Healy-Oden Trans-Arctic expedition in 2005 and the Lomonosov Ridge off Greenland expedition in 2007. LÄS MER

7. 25. Origin of organic compounds in fluids from ultramafic-hosted hydrothermal vents of the Mid-Atlantic Ridge

   Författare :Cécile Konn; Nils Holm; Jean-Luc Charlou; Barbara Sherwood Lollar; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Serpentinisation; hydrocarbons; organic compounds; ultramafic; hydrothermal; geochemistry; origin of life; Other earth sciences; Övrig geovetenskap; Other chemistry; Övrig kemi; Exogenous geochemistry; Exogen geokemi; geokemi; Geochemistry;

   Sammanfattning : Natural gas, primarily methane (CH4), is produced in substantial amounts in ultramafic-hosted hydrothermal systems. These systems could also generate oil (heavier hydrocarbons) and the first building blocks of life (prebiotic molecules). In the presence of iron bearing minerals, serpentinisation reactions generate H2. LÄS MER