Avancerad sökning

Visar resultat 1 - 5 av 53 avhandlingar som matchar ovanstående sökkriterier.

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

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

   Sammanfattning : 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. LÄS MER

3. 2. Marine non-heterocystous cyanobacteria : diazotrophic characterization & molecular phylogeny

   Författare :Pernilla Lundgren; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Cyanobakterier;

   Sammanfattning : .... LÄS MER

4. 3. Significance of N2 fixing planktonic symbioses for open ocean ecosystems

   Författare :Marcus Stenegren; Rachel A. Foster; Agneta Andersson; Stockholms universitet; []
   Nyckelord :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;

   Sammanfattning : 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). LÄS MER

5. 4. External Growth Control of Baltic Sea Cyanobacteria

   Författare :Anna Zakrisson; Ulf Larsson; Jakob Walve; Elena Gorokhova; Catherine Legrand; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Cyanobacteria; Baltic Sea; diazotrophs; diazotrophy; heterocysts; primary productivity; stable isotopes; sewage treatment; Marine Ecology; marin ekologi;

   Sammanfattning : The overall aim of the study was to provide better insights to the ecological role and impact of cyanobacteria in Baltic Sea (BS) bay, coastal and open sea areas. Biomass and heterocyst development of diazotrophic, heterocystous cyanobacteria were monitored over several years simultaneously as physical parameters such as nutrients and temperature. LÄS MER

7. 5. External Growth Control of Baltic Sea Cyanobacteria

   Författare :Anna Zakrisson; Ulf Larsson; Jakob Walve; Elena Gorokhova; Sanna Suikkanen; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Baltic Sea; cyanobacteria; nitrogen fixation; heterocysts; Aphanizomenon; Nodularia; water treatment; Himmerfjärden; sewage; climate; Marine Ecology; marin ekologi;

   Sammanfattning : In the Himmerfjärden Bay a large excess of nitrogen over phosphorus in the discharge from a large sewage treatment plant (STP) has suppressed growth of diazotrophic cyanobacteria in its inner parts. Implementation of nitrogen removal in the STP in 1997 drastically reduced nitrogen load and triggered growth of diazotrophs, mainly Aphanizomenon sp. LÄS MER