Sökning: "Varved annually laminated lake sediment"

Visar resultat 1 - 5 av 6 avhandlingar innehållade orden Varved annually laminated lake sediment.

  1. 1. Varved lake sediments and diagenetic processes

    Detta är en avhandling från Umeå : Ekologi, miljö och geovetenskap

    Författare :Veronika Gälman; Ingemar Renberg; Daniel Conley; [2009]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Varved annually laminated lake sediment; diagenesis; varve appearance; iron; sulfur; chemical speciation; iron cycling; carbon; nitrogen; stabile isotopes; δ13C; δ15N; NATURAL SCIENCES Earth sciences; NATURVETENSKAP Geovetenskap;

    Sammanfattning : 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. LÄS MER

  2. 2. Combining limnology and paleolimnology a refined understanding of environmental sediment signal formation in a varved lake

    Detta är en avhandling från Umeå : Umeå University

    Författare :Dominique Béatrice Maier; Christian Bigler; Sebastian Diehl; Jasmine E. Saros; [2017]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; varved lake sediments; diatom sediment signal formation; sequential sediment trap; seasonal process timing; ice thinning; varve compaction; climate impact; catchment properties; Earth Sciences with Specialization Environmental Analysis; geovetenskap med inriktning mot miljöanalys;

    Sammanfattning : Paleoclimatic archives, such as lake sediments, extend our understanding of terrestrial and aquatic ecosystem dynamics in relation to climate variability beyond the period covered by instrumental data. In this context, annually laminated (i.e. LÄS MER

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

    Detta är en avhandling från Quaternary Sciences, Department of Geology, Lund University

    Författare :Lovisa Zillén; [2003]
    Nyckelord :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;

    Sammanfattning : 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. LÄS MER

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

    Detta är en avhandling från Umeå : Umeå universitet, Institutionen för ekologi, miljö och geovetenskap

    Författare :Johan Rydberg; Richard Bindler; Carl Lamborg; [2010]
    Nyckelord :Mercury; retention; lake sediments; peatlands; environmental archives; sedimentation; diagenesis; vegetation; permafrost; Environmental Science; miljövetenskap;

    Sammanfattning : 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. LÄS MER

  5. 5. Functional clustering methods and marital fertility modelling

    Detta är en avhandling från Umeå : Umeå universitet

    Författare :Per Arnqvist; Sara Sjöstedt de Luna; Leif Nilsson; Helle Sørensen; [2017]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; censoring; Coale-Trussell model; EM-algorithm; functional data analysis; functional clustering; marital fertility; normal approximation; Poisson process; varved lake sediments; warping; Mathematical Statistics; matematisk statistik;

    Sammanfattning : This thesis consists of two parts.The first part considers further development of a model used for marital fertility, the Coale-Trussell's fertility model, which is based on age-specific fertility rates. A new model is suggested using individual fertility data and a waiting time after pregnancies. LÄS MER