Nitrogen oxides abundances

The stratosphere contains, however, only small amounts--a few tenths of a ppb-of chlorine free radicals of natural origin. They are produced by the decomposition of methyl chloride, CH3Q. The nitrogen oxides (NO and NO2) are more abundant and are produced in the stratosphere by the decomposition of nitrous oxide, N2O. Both CH3CI and N2O are of biological origin these compounds, released at the Earth s surface, are sufficiently stable to reach the stratosphere in significant amounts. 

Deriving electrical energy from nuclear fission produces almost no atmospheric pollutants, such as carbon dioxide, sulfur oxides, nitrogen oxides, heavy metals, and airborne particulates. Although not discussed in the text, there is also an abundant supply of fuel for nuclear fission reactors in the form of plutonium-239, which can be manufactured from uranium-238. Use the keyword Breeder Reactor on your Internet search engine to learn about how this is so. 

Those oxides with wide band gaps, such as y-Al203, MgO, etc., are also known to be efficient photocatalysts for the oxidation of ammonia, nitrogen oxides, and hydrocarbons [23-26]. When evaluating the possible role of these most abundant components of continental aerosols in the tropospheric photochemistry, their importance may be due to their photoactivity under irradiation not only in their main absorption bands, but also in the bands of surface chemisorbed species. For example, for dispersed Sn02, it was found that surface carbonates were formed upon CO2 adsorption, which in turn sensitized some surface photoreactions to light quanta with energies less than 2eV (below 600 nm) [27]. 

In the following, the atmospheric cycle of gaseous nitrous oxide will first be discussed. As we shall see, the pathway of this compound is related to the NOx cycle. After the discussion of N20, the abundance of ammonia gas (ammonium particles) will briefly be presented these can also be converted in the air to nitrogen oxides. Finally, the atmospheric cycle of NO will be outlined, including particulate nitrate. 

Table 9-9. Equilibrium Constants and Relative Abundances for Higher Nitrogen Oxides and Peroxides Originating as Addition Products from N02... 

The oxidation of N02 eventually leads to the formation of nitric acid and aerosol nitrate, which are deposited at the earth surface. The relevant oxidation pathways are indicated in Fig. 9-6. The following discussion deals first with observations of reaction intermediates then with tropospheric abundances of N02, PAN, and HN03/ aerosol nitrate, and finally with the budget of nitrogen oxides and their oxidation products in the troposphere. 

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