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Air Quality and Stationary Source Emission Control
terest in N2O is not in the troposphere (ground level to 8–15 km) where it is practically inert but in photodissociation reactions in the stratosphere. Bates and Hays (1967) indicate that the dissociation of N2O into NO and atomic nitrogen accounts for about 20 percent of the dissociation in the stratosphere. The NO thus formed provides an important sink reaction for ozone.
As an industrial emission, ammonia is produced mainly from coal and oil combustion but natural production from biological generation over land and ocean is many times greater than that from anthropogenic sources (250 to 1). NH3’s importance is the significant role it plays in atmospheric reactions in both the nitrogen and sulfur cycles. Nearly three-fourths of the NH3 is converted to ammonium ion condens ed in droplets or particles. These aerosols are then subject to the physical removal mechan isms of coagulation, washout, rainout and dry deposition.
In general, ambient background concentrations of NH3 vary directly with the intensity of biological activity. The highest concentrations occur in the summer and in the tropical latitudes. Concentrations, as reported by many investigators, range from 1 to 10 ppb (Strauss 1972).
Nitric Oxide-Nitrogen Dioxide
NO, a colorless, odorless gas, is formed naturally from the nitrates in various materials by bacteria and then is oxidized to NO2 (Peterson 1956).
Altschuller (1958) and others have reported very hazardous conditions for farm workers near closed silos where NO→NO2 bacterial production has resulted in toxic concentrations of several hundred ppm of NO2.