Sökning: "Biogeochemical cycles"

Visar resultat 6 - 10 av 40 avhandlingar innehållade orden Biogeochemical cycles.

  1. 6. Transformation of iron constituents during early diagenesis : in situ studies of a Baltic Sea sediment-water interface

    Författare :C. H. Magnus Lindström; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : The aim of the present study was to elucidate the mechanisms and kinetics of the transformation of iron constituents at the sediment-water interface and their interaction with other element cycles during early diagenesis, with emphasis on their relations with oxygen, phosphorus and sulphur. The investigation was carried out in situ at 10 m water depth on a nearshore Baltic Sea soft bottom sediment. LÄS MER

  3. 7. Marine nitrogen fixation : Cyanobacterial nitrogen fixation and the fate of new nitrogen in the Baltic Sea

    Författare :Isabell Klawonn; Helle Ploug; Lasse Riemann; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; biogeochemistry; nitrogen cycling; nitrogen fixation; cyanobacteria; Baltic Sea; Marine Ecology; marin ekologi;

    Sammanfattning : Biogeochemical processes in the marine biosphere are important in global element cycling and greatly influence the gas composition of the Earth’s atmosphere. The nitrogen cycle is a key component of marine biogeochemical cycles. LÄS MER

  4. 8. Changes in ocean geochemistry across the K-Pg boundary interval

    Författare :Tjördis Störling; Berggrundsgeologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; K-Pg boundary; Paleocene; stable silicon isotopes; sponge spicules; radiolaria; Cerithium Limestone;

    Sammanfattning : The Cretaceous - Paleogene boundary (K-Pg, 66 Ma) was a time interval with dramatic changes in the Earth’s climate and the ocean environment. It was characterized by severe disruptions of marine biogeochemical cycles due to a meteorite impact during a time of active volcanism. LÄS MER

  5. 9. Control factors of the marine nitrogen cycle : The role of meiofauna, macrofauna, oxygen and aggregates

    Författare :Stefano Bonaglia; Patrick Crill; Volker Brüchert; Per Hall; Chritoph Humborg; Risgaard-Petersen Nils; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Nitrogen cycle; denitrification; DNRA; anammox; anoxia; hypoxia; eutrophication; meiofauna; macrofauna; aggregates; cyanobacteria; Baltic Sea; geokemi; Geochemistry;

    Sammanfattning : The ocean is the most extended biome present on our planet. Recent decades have seen a dramatic increase in the number and gravity of threats impacting the ocean, including discharge of pollutants, cultural eutrophication and spread of alien species. LÄS MER

  7. 10. Shaped by the past: Resilience and ecological memory in microbial communities

    Författare :Sophia Renes; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES;

    Sammanfattning : Microorganisms play a fundamental role in global biogeochemical cycles, which are increasingly being altered by the current rapid changes in the environment, threatening biodiversity and the provisioning of key ecosystem services. This thesis addresses key uncertainties surrounding the assessment of ecological resilience and the role of previous disturbances in shaping the stability especially of microbial communities to future disturbances. LÄS MER