Search for dissertations about: "LAMINATED SEDIMENTS"

Showing result 1 - 5 of 11 swedish dissertations containing the words LAMINATED SEDIMENTS.

  1. 1. Varved lake sediments and diagenetic processes

    Author : Veronika Gälman; Ingemar Renberg; Daniel Conley; Umeå universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Varved annually laminated lake sediment; diagenesis; varve appearance; iron; sulfur; chemical speciation; iron cycling; carbon; nitrogen; stabile isotopes; δ13C; δ15N; Earth sciences; Geovetenskap;

    Abstract : Varved (annually laminated) sediments are of great interest for inference of past environmental conditions, as they provide dated records with high time resolution. After deposition, the sediment varves are affected by diagenesis; i.e., chemical, physical and biological changes that occur within the sediment. READ MORE

  2. 2. Studies of an elusive element : processes that influence the net retention of mercury in lake sediments and peatlands

    Author : Johan Rydberg; Richard Bindler; Carl Lamborg; Umeå universitet; []
    Keywords : Mercury; retention; lake sediments; peatlands; environmental archives; sedimentation; diagenesis; vegetation; permafrost; Environmental Science; miljövetenskap;

    Abstract : Because of its toxic nature mercury is a threat to both wildlife and human health, and thus, it is an element of concern in the environment. Currently much of the mercury emitted to the atmosphere is derived from anthropogenic sources – both direct emissions and re-emission of already deposited anthropogenic mercury. READ MORE

  3. 3. Magnetic properties of magnetosomal greigite and factors influencing its occurrence and preservation in Baltic Sea Littorina sediments

    Author : Maja Reinholdsson; Kvartärgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; Baltic Sea; deep basins; mineral magnetic properties; magnetotactic bacteria; magnetosomal greigite; laminated sapropels; organic carbon; geochemistry.;

    Abstract : The Baltic Sea is one of the world’s largest brackish water environments and is today suffering from, for example, eutrophication, spreading hypoxia, accumulations of contaminants and invasive organisms. These problems exist due to a combination of natural features that makes the Baltic Sea a sensitive ecosystem (such as long water residence time, limited water exchange, large catchment area), and anthropogenic pressures on land, (such as agriculture and land-use changes, large human populations and industries) and in the sea (such as transport, fishing and bottom-trawling). READ MORE

  4. 4. Setting the Holocene clock using varved lake sediments in Sweden

    Author : Lovisa Zillén; Kvartärgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; climate change; Physical geography; tephrochronology; palaeomagnetic secular variations; radiocarbon time-scale; Holocene varved lake sediments; varve chronology; geomorphology; pedology; cartography; climatology; Fysisk geografi; geomorfologi; marklära; kartografi; klimatologi;

    Abstract : The aim of this thesis was to study annually laminated (varved) Holocene lake sediment in Sweden, their formation and their potential as chronological and palaeoecological archives. Five lakes with continuous Holocene varved lake sediment sequences in northern (Västerbotten) and west central Sweden (Värmland) were investigated. READ MORE

  5. 5. Investigations of temporal changes in climate and the geomagnetic field via high-resolution radiocarbon dating

    Author : Anette Mellström; Kvartärgeologi; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; wiggle-matching; Radiocarbon dating; 14C; 2800 cal BP; climate change; solar activity; palaeomagnetism; lake sediments; varves; post-depositional remanent magnetisation; PDRM; lock-in; peat deposits; Sweden;

    Abstract : Geological archives have shown periods of abrupt climate change in the relatively stable Holocene epoch (last ca. 11 700 years). One of these periods was around 2800 cal BP. Several records, mainly from Europe, reveal a shift towards wetter, cooler and windier conditions. READ MORE