Sökning: "lake sediments"

Visar resultat 6 - 10 av 140 avhandlingar innehållade orden lake sediments.

  1. 6. Infrared spectroscopy as a tool to reconstruct past lake-ecosystem changes : Method development and application in lake-sediment studies

    Författare :Carsten Meyer-Jacob; Richard Bindler; Hendrik Vogel; Jan Karlsson; John F. Boyle; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Fourier transform infrared spectroscopy; visible-near infrared spectroscopy; PLS regression; biogenic silica; climate change; carbon cycling; lake-water quality; geochemistry; paleolimnology; Holocene; Lake El’gygytgyn; Torneträsk;

    Sammanfattning : Natural archives such as lake sediments allow us to assess contemporary ecosystem responses to climate and environmental changes in a long-term context beyond the few decades to at most few centuries covered by monitoring or historical data. To achieve a comprehensive view of the changes preserved in sediment records, multi-proxy studies – ideally in high resolution – are necessary. LÄS MER

  3. 7. Varved lake sediments and diagenetic processes

    Författare :Veronika Gälman; Ingemar Renberg; Daniel Conley; Umeå universitet; []
    Nyckelord :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;

    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

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

    Författare :Johan Rydberg; Richard Bindler; Carl Lamborg; Umeå universitet; []
    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. 9. Diatoms in Lake Duluti : Tracking Environmental Variability in Northern Tanzania during the Past 1000 Years

    Författare :Helena Öberg; Lars-Ove Westerberg; Karin Holmgren; Jan Risberg; Robert Marchant; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Paleolimnology; Tanzania; Diatoms; Climate change; Crater lake; Physical Geography; naturgeografi;

    Sammanfattning : The tropics are the regions which are least understood climatically and new data on past climate variability is necessary for reliable future modeling of climate change. This thesis contributes with new paleoenvironmental information from a small crater lake in northern Tanzania and provides an additional link between the integrated history of climate, environment and socioeconomic variability in tropical Africa. LÄS MER

  7. 10. Metal speciation and historical trends in lake sediments

    Författare :Tomas Hjorth; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Sediments Geology ; Sediment;

    Sammanfattning : .... LÄS MER