Sökning: "Nitrogen"

Visar resultat 21 - 25 av 1355 avhandlingar innehållade ordet Nitrogen.

  1. 21. Vegetation changes on Swedish mires : Effects of raised temperature and increased nitrogen and sulphur influx

    Författare :Urban Gunnarsson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Developmental biology; Acidification; growth; long-term studies; mires; nitrogen; species richness; Sphagnum; succession; sulphur; temperature; Utvecklingsbiologi; Developmental biology; Utvecklingsbiologi; ekologisk botanik; Ecological Botany;

    Sammanfattning : Since the start of the industrialisation, the deposition of nitrogen and sulphur and the atmospheric concentrations of greenhouse gases have increased. The main objectives of this study were to find how these changes in climate and deposition can change the vegetation of mire ecosystems and the growth of Sphagnumspecies. LÄS MER

  3. 22. Nitrogen fixation among marine bacterioplankton

    Författare :Kjärstin H. Boström; Lasse Riemann; Åke Hagström; Grieg Steward; Högskolan i Kalmar; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Bacterioplankton; Nitrogen fixation; Bakterioplankton; Kvävefixering; Cyanobakterier; Kvävefixerande bakterier; Microbiology; Mikrobiologi; Mikrobiologi; Microbiology;

    Sammanfattning : While bacterioplankton indisputably control vital biogeochemical paths in the cycling of carbon and nutrients in the world’s oceans, our knowledge about the functional and genetic diversity of bacterioplankton communities is negligible. In this thesis, molecular and more traditional microbiological methods were used to study the specific function of N2-fixation and in a general sense diversity of marine bacterioplankton species. LÄS MER

  4. 23. Molecular Beam Studies of Interactions Between Ice Surfaces and Atmospherically Relevant Molecules

    Författare :Liza Romero Lejonthun; Göteborgs universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; molecular beam; surface; surface scattering; collision; water ice; ice; chlorine; nitrogen oxides; nitrogen monoxide; nitrogen dioxide; dinitrogen tetroxide; dinitrogen pentoxide; nitric acid; helium; graphite;

    Sammanfattning : The discovery of the ozone hole over Antarctica in 1985 was one of the environmental issues that attracted most attention worldwide in the end of the last century. The cause of the ozone hole formation was proven to be coupled to the emission of chlorofluorocarbons (CFCs). LÄS MER

  5. 24. Microbial Communities in Boreal Peatlands : Responses to Climate Change and Atmospheric Nitrogen and Sulfur Depositions

    Författare :Magalí Martí Genero; Bo Svensson; Åsa Danielsson; Torben Christensen; Linköpings universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; Microbial communities; methanogens; plant communities; peatland; temperature; nitrogen; long-term; field experiment; high-throughput sequencing; Microbiella samhällen; metanogener; växtsamhällen; myrar; torv; temperatur; kväve; långtid; fältexperiment; high-throughput-sekvensering;

    Sammanfattning : Myrmarker har en stor roll i regleringen av den globala kolbalansen och koncentrationerna av koldioxid och metan i atmosfären, vilket gör dem till speciellt viktiga ekosystem ur ett klimatförandringsperspektiv. Förändringar av myrmarker genom naturlig utveckling eller antropogen påverkan kan därför få långtgående störningar av myrars klimatreglerande funktion. LÄS MER

  7. 25. The role of benthic macrofauna in nitrogen cycling in eutrophic lake sediment

    Författare :Jonas Martin Svensson; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; nitrogen retention; nitrous oxide; oligochaetes; chironomids; mineralisation; nitrification; denitrification; eutrophic; sediment; lake; Macrofauna; nitrogen cycling; fish reduction.; Ecology; Ekologi;

    Sammanfattning : This thesis concerns the role of sediment-living macrobenthos in the cycling of nitrogen species and nitrogen transformation in eutrophic freshwater sediments. In my thesis I have, employing 15N-isotope techniques in laboratory experiments, shown the importance of infaunal chironomid larvae and oligochaetes on denitrification in eutrophic lake sediments. LÄS MER