Sökning: "geochemistry"

Visar resultat 1 - 5 av 264 avhandlingar innehållade ordet geochemistry.

  1. 1. 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; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Serpentinisation; hydrocarbons; organic compounds; ultramafic; hydrothermal; geochemistry; origin of life; NATURAL SCIENCES Earth sciences Other earth sciences; NATURVETENSKAP Geovetenskap Övrig geovetenskap; NATURAL SCIENCES Chemistry Other chemistry; NATURVETENSKAP Kemi Övrig kemi; NATURAL SCIENCES Earth sciences Exogenous earth sciences Exogenous geochemistry; NATURVETENSKAP Geovetenskap Exogen geovetenskap 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

  2. 2. Geochronology of the Oklo and Bangombé fossil natural fission reactors : tracing the effects of geological events

    Detta är en avhandling från Stockholm : Department of Geology and Geochemistry, Stockholm University

    Författare :Lena Zetterström Evins; Ian Williams; [2002]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Historisk geologi; Geology; geologi; geokemi; Geochemistry;

    Sammanfattning : Thesis to be publicly defended for the degree of Doctor of Philosophy, in lecture room De Geersalen, Svante Arrhenius väg 8a, Stockholm, Friday February 1, 2002 at 10.00 am. Two billion years ago, natural fission reactions took place in the Oklo and Bangombé uranium ores in Gabon, West Equatorial Africa. LÄS MER

  3. 3. Ocean chemistry and the evolution of multicellularity

    Detta är en avhandling från Stockholm : Department of Geological Sciences, Stockholm University

    Författare :Emma U. Hammarlund; Stefan Bengtson; Donald Canfield; Nils Holm; Graham Budd; [2012]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Geochemistry; biology; paleontology; evolution; multicellularity; geokemi; Geochemistry;

    Sammanfattning : Oxygen has been assumed to be a vital trigger for the evolution of multicellular life forms on Earth, partly based on its power to promote substantial energy flux in cell respiration and partly as biosynthesis of compounds like collagen require oxygen. However, the co-evolution of large life and the Earth’s chemical environment is not well understood at present, and there is particular disagreement in the field about whether the Cambrian explosion of animal life forms was a chemical or biological event. LÄS MER

  4. 4. Aqueous geochemistry of pit lakes two cases studies at Rävlidmyran and Udden, Sweden

    Detta är en avhandling från Luleå : Luleå tekniska universitet

    Författare :Lu Ming; [2002]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Applied Geology; Tillämpad geologi;

    Sammanfattning : Two abandoned pit lakes in northern Sweden were studied in order to improve the understanding of the geochemistry of pit lakes, Rävlidmyran Pit Lake and Udden Pit Lake. Both lakes show strong similarity with other mining lakes in terms of low pH and high metal and sulphate contents. LÄS MER

  5. 5. Hydrogeological and geochemical assessment of aquifer systems with geogenic arsenic in Southeastern Bangladesh Targeting low arsenic aquifers for safe drinking water supplies in Matlab

    Detta är en avhandling från Stockholm : KTH Royal Institute of Technology

    Författare :Mattias von Brömssen; Prosun Bhattacharya; David Polya; [2012]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Arsenic; Bangladesh; drinking water; groundwater; sustainability; geochemistry; hydrogeology; modelling;

    Sammanfattning : Naturally occurring arsenic (As) in Holocene aquifers in Bangladesh have undermined a long success of supplying the population with safe drinking water. Arsenic is mobilised in reducing environments through reductive dissolution of Fe(III)-oxyhydroxides. LÄS MER