Total fixed nitrogen

Modeling reduction-oxidation reactions that impact total fixed nitrogen in the oceans... 

The reduction of fuel-N to molecular nitrogen in air staging is favored in the fuel rich primary combustion zone ( Fig. 3 ). Investigations on fixed bed wood furnaces have shown that a minimum of the Total Fixed Nitrogen (TFN = HCN+NH3+NO+ NO2+2N2O emission from the primary combustion zone is reached for a stoichiometric ratio of 0.7 to 0.8 and a temperature of 1100 C to 1200 °C and providing a mean residence time of 0.5 s. After the reduction zone the combustion is completed in the burnout zone by injection of the excess air. 

In freshwater aquatic systems, cyanobacteria are believed to account for up to 78% of the total fixed nitrogen (Mague, 1977). These symbiotic organisms have been found to vary with season and often to precede, and be part of, algal blooms. This can lead to eutrophication of an aquatic system, by supplying NH3, one of the nutrients essential to all plant life. In... 

The cyanobacteria are considered the main N-fixing organisms in both freshwater and marine ecosystems. Some estimates have shown that these species are responsible for up to 80% of total fixed nitrogen in freshwaters. Cyanobacteria are widespread so that significant nitrogen fixation is possible on local, regional and global scales. 

Figure 6-9. Cross section of the non-adiabatic channel of NO synthesis, O + N2 NO + N, as function of relative velocity u of atomic oxygen and molecular nitrogen assuming fixed values of their total energy, including internal degrees of freedom.

Lew, M., 1981. The distribution of some major and trace elements in sediments of the Atlantic Ocean (DSDP samples) 2. The distribution of total, fixed and organic nitrogen. Chem. Geol. 33 225-235. 

Fig. 8. Transient NO emissions at synthetic wastes nitrogen contents of (D), 1% ( ), 3% and (0)> 10%, where the % of O2 is 2ero. Aniline is used as a nitrogen source and toluene is used to keep the total hydrocarbon weight fixed at 35 g (29).

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