Sökning: "nitrogen accumulation"

Visar resultat 36 - 40 av 85 avhandlingar innehållade orden nitrogen accumulation.

  1. 36. Nitrate stable isotopes and major ions in snow and ice from Svalbard

    Författare :Carmen Paulina Vega Riquelme; V. A. Pohjola; R. Pettersson; E. Isaksson; C. E. Bøggild; Kumiko Goto-Azuma; Uppsala universitet; []
    Nyckelord :nitrate stable isotopes; nitrate; NOx proxies; ice cores; percolation; ion relocation; Svalbard; stabila isotoper av nitrat; nitrat; indikator för kväveoxider; iskärnor; perkolation; joniska omlokalisering; Svalbard; Earth Science with specialization in Physical Geography; Geovetenskap med inriktning mot naturgeografi;

    Sammanfattning : Increasing atmospheric reactive nitrogen (Nr), as consequence of human activities, has generated accumulation of nitrate (NO3-) in Arctic regions. The Arctic has fragile nitrogen limited ecosystems that can be altered by increases of dry or wet deposition of Nr. LÄS MER

  3. 37. Denitrification as an adaptive trait in soil and groundwater bacteria

    Författare :Christer Bergwall; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; microcosm; forest soil; aquifer; groundwater; reductase; nitrous oxide; nitric oxide; nitrite; nitrate; selection; adaptation; bacteria; nitrification; Denitrification; dissimilatory nitrate reduction to ammonium; fertiliser; 15NO3-; 15NH4 ; Ecology; Ekologi;

    Sammanfattning : The focus of the thesis is on selection and adaptation processes in bacteria with emphasis on denitrifying bacteria in groundwater. Other nitrogen transformation processes such as dissimilatory nitrate reduction to ammonium (nitrate ammonification) and nitrification of forest soil bacteria are briefly discussed. LÄS MER

  4. 38. Stable isotope studies of contaminant and material transport in Baltic pelagic food-webs

    Författare :Carl Rolff; Nicholas J.P Owen; Stockholms universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; zoologi; Zoology;

    Sammanfattning : Both carbon and nitrogen appear in nature as different stable isotopes. Many natural processes affect the relative proportions of heavy and light isotopes in predictable ways. The isotopic composition of organisms and other organic materials can therefore serve as records of the processes involved in their formation. LÄS MER

  5. 39. Halomonas species as a source of poly(3-hydroxybutyrate). Preparation of hydrophilic macroporous polymer scaffolds

    Författare :Daniel Guzmán; Bioteknik; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Halomonas species; poly 3-hydroxybutyrate ; genome sequence; Fed-batch cultivation; macroporous scaffolds;

    Sammanfattning : This thesis presents studies on moderately halophilic bacteria belonging to the family Halomonadaceae that accumulate polyhydroxybutyrate (PHB) in high amounts when grown under conditions of nitrogen limitation. PHB is the simplest homopolymer belonging to the class of polyhydroxyalkanoates (PHAs), the biopolyesters that can biodegraded in the environment to carbon dioxide and water and are hence attractive substitutes for fossil-derived plastics. LÄS MER

  7. 40. Iodine-Metal Surface Interactions under Severe Accident Conditions in a Nuclear Power Plant

    Författare :Henrik Glänneskog; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES; containment; reactive metals; BWR; adsorption; iodine; radiolysis;

    Sammanfattning : In the event of a severe nuclear reactor accident, iodine will be released from the fuel and eventually enter the containment. Radioactive iodine isotopes constitute both an acute and a long-term threat to humans, owing to its half-life and its accumulation in the thyroid gland. LÄS MER