Search for dissertations about: "N2 fixation"

Showing result 1 - 5 of 32 swedish dissertations containing the words N2 fixation.

  2. 1. Marine nitrogen fixation : Cyanobacterial nitrogen fixation and the fate of new nitrogen in the Baltic Sea

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

    Abstract : 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. READ MORE

  4. 2. Nitrogen fixation among marine bacterioplankton

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

    Abstract : 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. READ MORE

  5. 3. Cyanobacterial Nitrogen Fixation in the Baltic Sea : With focus on Aphanizomenon sp

    Author : Jennie B. Svedén; Jakob Walve; Helle Ploug; Angela Wulff; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; cyanobacteria; Baltic Sea; nitrogen fixation; Aphanizomenon sp.; dissolved nitrogen; particulate nitrogen; sedimentation; Marine Ecology; marin ekologi;

    Abstract : Cyanobacteria are widely distributed in marine, freshwater and terrestrial habitats. Some cyanobacterial genera can convert di-nitrogen gas (N2) to bioavailable ammonium, i.e. perform nitrogen (N) fixation, and are therefore of profound significance for N cycling. READ MORE

  6. 4. Functional Traits in Sphagnum

    Author : Fia Bengtsson; Håkan Rydin; Gustaf Granath; Cronberg Nils; Sari Juutinen; Uppsala universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; peat mosses; functional traits; NPP; decay resistance; N2 fixation; desiccation resistance; climate; Biology with specialization in Ecological Botany; Biologi med inriktning mot ekologisk botanik;

    Abstract : Peat mosses (Sphagnum) are ecosystem engineers that largely govern carbon sequestration in northern hemisphere peatlands. I investigated functional traits in Sphagnum species and addressed the questions: (I) Are growth, photosynthesis and decomposition and the trade-offs between these traits related to habitat or phylogeny?, (II) Which are the determinants of decomposition and are there trade-offs between metabolites that affect decomposition?, (III) How do macro-climate and local environment determine growth in Sphagnum across the Holarctic?, (IV) How does N2 fixation vary among different species and habitats?, (V) How do species from different microtopographic niches avoid or tolerate desiccation, and are leaf and structural traits adaptations to growth high above the water table?Photosynthetic rate and decomposition in laboratory conditions (innate growth and decay resistance) were related to growth and decomposition in their natural habitats. READ MORE

  7. 5. Significance of N2 fixing planktonic symbioses for open ocean ecosystems

    Author : Marcus Stenegren; Rachel A. Foster; Agneta Andersson; Stockholms universitet; []
    Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; nitrogen fixation; diazotrophs; symbiosis; DDA; cyanobacteria; qPCR; piecewise SEM; microarray; tropics; subtropics; marine; open ocean; Richelia; Calothrix; Marine Ecology; marin ekologi;

    Abstract : Di-nitrogen (N2) fixers, also called diazotrophs, are able to reduce atmospheric N2 into bioavailable nitrogen, giving them an advantage in open ocean regions with low dissolved inorganic nitrogen concentrations. The focus of this thesis are three lineages of symbiotic heterocystous filamentous types (het-1, het-2 and het-3), that associate with several genera of microalgae called diatoms (collectively referred to as Diatom Diazotroph Associations, DDAs). READ MORE