Page 203 - Fundamentals of Air Pollution

III. Gas-Phase Chemical Reaction Pathways 169

TABLE 12-3
Hydrocarbon Compounds Identified in Ambient Air Samples from St. Petersburg, Florida

Acetaldehyde m-Ethyltoluene Methylcyclohexane Propene
Acetylene o-Ethyltoluene 3-Methylhexane n-Propylbenzene
1,3-Butadiene p-Ethyltoluene 2-Methylpentane Toluene
H-Butane n-Heptane Nonane 2,2, 4-Trimethy Ipen tane
frans-2-Butene Isobutane n-Pentane m-Xylene
Cyclopentane Isobutylene 1-Pentene o-Xylene
n-Decane Isopentane ds-2-Pentene p-Xylene
2, 3-Diinethylpentane Isopropyl benzene frans-2-Pentene 1,2,4-Trimethylbenzene
Ethane Limonene alpha-Pinene 1,3, 5-Trimethylbenzene
Ethylbenzene Methane teta-Pinene
Ethylene 2-Methyl-l-butene Propane
Source: Lonneman, W. A., Seila, R. L., and Bufalini, J. J., Environ. Sci. Technol. 12, 459-463
(1978).

to form nitrogen dioxide, ozone, and other oxidation products such as
peroxyacyl nitrate (PAN) and aldehydes. The complete process is very
complicated, with many reaction steps.
The principal components of atmospheric chemical processes are hydro-
carbons, oxides of nitrogen, oxides of sulfur, oxygenated hydrocarbons,
ozone, and free radical intermediates. Solar radiation plays a crucial role
in the generation of free radicals, whereas water vapor and temperature
can influence particular chemical pathways. Table 12-4 lists a few of the
components of each of these classes. Although more extensive tabulations
may be found in "Atmospheric Chemical Compounds" (8), those listed in

Fig. 12-2. NO-NO 2-O 3 ambient concentration profiles from average of four Regional Air
Monitoring Stations (RAPS) in downtown St. Louis, Missouri (USA) on October 1, 1976.
Source: RAPS, Data obtained from the 1976 data file for the Regional Air Pollution Study
Program. U.S. Environmental Protection Agency, Research Triangle Park, NC, 1976.