Sökning: "iron cycling"

Visar resultat 1 - 5 av 31 avhandlingar innehållade orden iron cycling.

  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. Iron in the Lena River basin, NE Russia Insights from microscopy, spectroscopy and isotope analysis

    Detta är en avhandling från Stockholm : Department of Geological Sciences, Stockholm University

    Författare :Catherine Hirst; Carl-Magnus Mörth; Per Andersson; Mats Erik Åström; [2018]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; iron; reactivity; isotopes; permafrost; river; Arctic; maringeologi; Marine Geology;

    Sammanfattning : Iron is an important mediator of biotic and abiotic processes on the Earth’s surface, being an electron acceptor in organic matter degradation, a surface for organic matter and trace element adsorption, and a required element for enzymatic processes during primary production. Yet, the role of iron as a mediator of carbon and trace element cycling in high latitude, permafrost-dominated regions remains poorly investigated. LÄS MER

  3. 3. Thermal Cycling, Creep- and Tensile Testing of Cast Exhaust Materials at Elevated Temperatures

    Detta är en avhandling från STOCKHOLM : KTH Royal Institute of Technology

    Författare :Christian Öberg; Stefan Jonsson; Henrik Östling; [2018]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; creep; constant-load; thermal cycling; tensile test; cast materials; cast iron; exhaust materials.; Materials Science and Engineering; Teknisk materialvetenskap;

    Sammanfattning : An exhaust manifold of a truck engine is subjected to tough conditions. As the truck is started, operated and shut down, it becomes subjected to thermal cycling up to around 800°C. At such high temperatures, corrosion, fatigue and creep are active degradation mechanisms. LÄS MER

  4. 4. Degradation Mechanisms of Heat Resistant Steel at Elevated Temperatures In an Iron Ore Pelletizing Industry

    Detta är en avhandling från Luleå : Luleå University of Technology

    Författare :Erik A. A. Nilsson; Marta-Lena Antti; Ragnar Tegman; Jan-Erik Svensson; [2017]
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; stainless steel; Grate-Kiln; microstructure; corrosion; as-casted; thermal cycling; erosion; deposition; Engineering Materials; Materialteknik;

    Sammanfattning : This thesis focuses on the different degradation mechanisms of the stainless steel in a travelling grate in a Grate-Kiln iron ore pellet indurator. The travelling grate is a conveyor belt that transports green-body pellets to a rotary kiln while the pellets are being dried and pre-heated to a temperature of 900-1100 °C by recycled hot air. LÄS MER

  5. 5. Nitrogen-cycling tracing methods Case studies at cold-climate mine sites in northern Sweden

    Detta är en avhandling från Luleå : Luleå University of Technology

    Författare :Lino Nilsson; Anders Widerlund; Andreas Bryhn; [2018]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Applied Geochemistry; Tillämpad geokemi;

    Sammanfattning : High nitrogen effluents from mine sites is an environmental issue which has received relatively little attention historically. In recent years a number of studies have showed the environmental effects of high nitrogen discharge to natural water bodies, which include local eutrophication, high risk of acute reducing conditions and changed species composition in the receiving waters. LÄS MER