Sökning: "NATURAL SCIENCES Earth sciences Exogenous earth sciences"

Visar resultat 1 - 5 av 6 avhandlingar innehållade orden NATURAL SCIENCES Earth sciences Exogenous earth sciences.

1. 1. Unraveling the importance of thiol compounds on mercury speciation, uptake and transformation by the iron-reducer Geobacter sulfurreducens

   Författare :Mareike Franziska Gutensohn; Erik Björn; Ulf Skyllberg; Jeffra K. Schaefer; Vera Slaveykova; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; mercury; low molecular mass thiols; speciation; uptake; methylation; reduction; Hg 0 ; Hg II ; MeHg; Geobacter sulfurreducens; ICP-MS; LC-MS MS; X-ray absorption spectroscopy; cell physiology;

   Sammanfattning : The biogenic methylation of inorganic, divalent mercury (Hg(II)) by methylating microorganisms leads to formation and bioaccumulation of monomethyl mercury (MeHg) in the environment and can cause severe damage to ecosystems and human health. Diverse microorganisms carry the gene sequence hgcAB and are able to methylate Hg(II) intracellularly. LÄS MER

3. 2. 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

4. 3. Identification and origin of potential background carcinogens : endogenous isoprene and oxiranes, dietary acrylamide

   Författare :Eden Tareke; Rafter Joseph; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Environmental chemistry; Miljökemi; Environmental Chemistry; miljökemi;

   Sammanfattning : The primary aims of this thesis are to discover carcinogens in the general population by identification of products of reaction with hemoglobin (Hb adducts) in blood from humans without known exposure, and tracing the origin of the adducts. Chemicals and/or their metabolites forming Hb adducts mostly also react with DNA and may thus cause mutations, a key event in carcinogenesis. LÄS MER

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

   Författare :Emma Engström; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Applied Geology; Tillämpad geologi;

   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

7. 5. Fractionation of the stable silicon isotopes studied using MC-ICP-MS : analytical method developments and applications in geochemistry

   Författare :Emma Engström; Ben Reynolds; Luleå tekniska universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Applied Geology; Tillämpad geologi;

   Sammanfattning : In spite of the high Si abundance in natural systems, expected significant mass-dependent fractionations, and the importance of the element in many areas of the Earth sciences (focusing on e.g. LÄS MER