Sökning: "nitrogen deposition"

Visar resultat 6 - 10 av 125 avhandlingar innehållade orden nitrogen deposition.

1. 6. Welds in the lean duplex stainless steel LDX 2101 : effect of microstructure and weld oxides on corrosion properties

   Författare :Elin M. Westin; John Ågren; KTH; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Duplex stainless steel; welding; weld metal; HAZ; nitrogen; manganese; austenite formation; phase balance; precipitates; pitting resistance; heat input; solidification; element loss; evaporation; deposition; weld oxides; discoloration; mechanical properties; thermo-mechanical simulation; Geeble; GTA; laser; LOM; SEM; EDS; TEM; Leco; EPMA; ferroxyl test; XPS; post weld cleaning; pickling; Materials science; Teknisk materialvetenskap;

   Sammanfattning : Duplex stainless steels are a very attractive alternative to austenitic grades due to their higher strength and good corrosion performance. The austenitic grades can often be welded autogenously, while the duplex grades normally require addition of filler metal. LÄS MER

3. 7. Ectomycorrhizal fungi: Their role in nitrogen retention and carbon sequestration in northern coniferous forests

   Författare :Adam Bahr; MEMEG; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Ectomycorrhizal fungi; Carbon sequestration; Nitrogen deposition; Nitrogen leakage; Field survey; Boreo-nemoral forest; Boreal Forest; Ergosterol; Free ergosterol; Mesh-bags; Multivariate analysis;

   Sammanfattning : Almost all northern forest tree species live in symbioses with ectomycorrhizal fungi (EMF). The trees allocate up to half of the photoassimilated carbon (C) through the roots to EMF. In return EMF deliver nutrients from both inorganic and organic sources in the soil, as well as water. LÄS MER

4. 8. Nitrogen, parasites and plants : key interactions in boreal forest ecosystems

   Författare :Joachim Strengbom; Lars Ericson; Gaius R Shaver; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Critical loads; Deschampsia flexuosa; amino acids; mycorrhizal fungi; natural enemies; N deposition; N limitation; vegetational composition; Valdensia heterodoxa; Vaccinium myrtillus;

   Sammanfattning : In the work described in this thesis I studied how increases in nitrogen (N) inputs may affect plant community structure in boreal forest understorey vegetation. These phenomena were investigated in N fertilization experiments and along a national N deposition gradient. LÄS MER

5. 9. Responses of peatland vegetation to enhanced nitrogen

   Författare :Magdalena Wiedermann; Lars Ericson; Juul Limpens; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sphagnum; nitrogen; peatlands; soluble amino acids; gradient study; field experiment; Biology; Biologi;

   Sammanfattning : Human alteration of the global nitrogen (N) cycle has had major impacts on naturally N-limited ecosystems worldwide. Peatlands, dominated by peat mosses, Sphagnum species, represent one such sensitive ecosystem. LÄS MER

7. 10. 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