Sökning: "diatom silica"

Visar resultat 1 - 5 av 10 avhandlingar innehållade orden diatom silica.

  1. 1. Diatom-rich sediment formation in lakes

    Författare :Petra Zahajská; Kvartärgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Silicon; silica; diatom; biogenic silica; lake; sediment; stable Si isotopes; Ge Si; Yellowstone; Northern Sweden;

    Sammanfattning : Unicellular photosynthetic golden algae called diatoms are one of the most abundant silicifying organisms. Diatoms take up silicon and build their frustules, in the form of biogenic silica (BSi), which have high preservation potential, and thus are found in sediments. LÄS MER

  3. 2. Silicon cycling in the Baltic Sea : Trends and budget of dissolved silica

    Författare :Liana Papush; Åsa Danielsson; Lars Rahm; Petra Tallberg; Linköpings universitet; []
    Nyckelord :Dissolved silica; trends; nutrient; nutrient ratios; diatoms; Redfield; limitation; eutrophication; riverine load; budget; fluxes; accumulation; retention; optimisation; Baltic Sea; Löst kisel; trender; näringsämne; näringsämnens kvoter; kiselalger; Redfield; tillväxtbegränsning; övergödning; flodtillförsel; budget; flöden; ackumulering; retention; optimering; Östersjön; NATURAL SCIENCES; NATURVETENSKAP;

    Sammanfattning : The dissolved silicon (DSi) has a crucial role for growth of a large group of primary producers – diatoms and, hence, impact on functioning of the aquatic food web. This thesis contributes to an increased understanding of the modifications of the DSi cycling in the Baltic Sea. LÄS MER

  4. 3. Diatom silica in lake sediments and suspended matter

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

    Sammanfattning : .... LÄS MER

  5. 4. Holocene climate and atmospheric circulation changes in northern Fennoscandia : Interpretations from lacustrine oxygen isotope records

    Författare :Christina E. Jonsson; Gunhild Rosqvist; Jan Seibert; Philip Barker; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; oxygen isotope; diatom silica; lake sediment; atmospheric circulation; North Atlantic Oscillation; northern Fennoscandia; The Holocene; Little Ice Age; Physical geography; Naturgeografi; Physical Geography; naturgeografi;

    Sammanfattning : This thesis investigates how variations in the oxygen isotopic composition of lake waters in northern Fennoscandia are recorded in lake sediment archives, especially diatoms, and how these variations can be used to infer past changes in climate and atmospheric circulation. Results from analyses of the oxygen isotopic composition of lake water samples (δ18Olakew) collected between 2001 and 2006 show that δ18O of northern Fennoscandian lakes is mainly controlled by the isotopic composition of the precipitation (δ18Op). LÄS MER

  7. 5. Characterization and preparation of lightweight silica based ceramics for building applications

    Författare :Edwin Escalera; Luleå tekniska universitet; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Materialteknik; Engineering Materials;

    Sammanfattning : Bolivia is a country with considerable quantities of non-metallic resources. Some important deposits of these resources are located in the high and cold Altiplano as well as in the tropical areas. These deposits are not being exploited industrially but both areas have production of some ceramics in a handmade and empiric way. LÄS MER