Ho

ß-Amyrin
Lupeol

Calamenene

Calamenene

5, 6, 7, 8-Tetrahydrocadalene

5, 6, 7, 8-Tetrahydrocadalene

Abieta-7,13-diene

COOH Abietic Acid

COOH Pimaric Acid

COOH Pimaric Acid

Retene

FIGURE 9.45 Some naturally occurring organics found in tropospheric particles (adapted from Simoneit et at., 1988, 1989).

example, long-chain alkenones have been observed in New Zealand and attributed to an algal source but not on American Samoa (Sicre et al., 1990a).

In addition to these nonviable organics, there are, of course, a whole host of viable species, such as fungi, bacteria, pollen, yeasts, and viruses, also present in the atmosphere. For more details of the variety of organics found in aerosols in various locations and their concentrations, the reader is referred to papers by Duce et al. (1983), Chen and Simoneit (1994), and Rogge et al. (1993d).

b. Organics in Anthropogenically Influenced and Aged Aerosol Particles

Particles collected in regions influenced by anthropogenic emissions and those in aged air masses where there has been ample opportunity for oxidation are even more complex than those in remote regions. Thus, they may contain not only the organics from biogenic emissions but also complex organics that either have been directly emitted from sources associated with human activities or have been formed in air from reactions of primary emissions.

(1) Direct emissions To fully appreciate the complexity of even those organics that are directly emitted

17a(H), 2ip(H)R-Hopanes

Extended tricyclic terpanes

Extended tricyclic terpanes from various sources in urban areas, the reader should consult the papers by Simoneit, Cass, and co-workers (e.g., see Standley and Simoneit, 1987; Simoneit et al., 1988, 1993; Mazurek et al., 1991; and Rogge et al., 1993a, 1993b, 1993c, 1993e, 1994, 1996, 1997a, 1997b, 1998) in which they characterize organics from various sources. For example, automobiles and heavy-duty diesel trucks are shown to be sources of n-alkanes, n-alkanoic acids, aromatic aldehydes and acids, poly-cyclic aromatic hydrocarbons (PAH; see Chapter 10), oxidized PAH derivatives, steranes, pentacyclic triter-panes, and azanapthalenes (Rogge et al., 1993a); abrasion of leaf surfaces a source of n-alkanes, n-alkanoic and n-alkenoic acids, n-alkanols, n-alkanals, and terpenoids (Rogge et al., 1993b); combustion of natural gas home appliances a source of n-alkanes and n-alkanoic acids, PAH, oxidized PAH derivatives, and azaarenes (although total particle emissions from this source are fairly low) (Rogge et al., 1993c); and wood smoke a source of compounds such as diterpenoid acids, retene, dehydroabietic acid (Fig. 9.45), and 13-isopropyl-5a-podocarpa-6,8,ll,13-tetraen-16-oic acid (Standley and Simoneit, 1990; Mazurek et al., 1991; Rogge et al., 1993d). Other characteristic compounds from wood smoke include derivatives of 2-me-thoxyphenol (guaiacol) and 2,6-dimethoxyphenol (syringol) (Hawthorne et al., 1988). Figure 9.46 shows

18a-(H)-Oleanane R

Steranes

Steranes

Pristane Phytane

FIGURE 9.46 Some organics from petroleum that are found in tropospheric particles (adapted from Simoneit et al., 1988).

Pristane Phytane

FIGURE 9.46 Some organics from petroleum that are found in tropospheric particles (adapted from Simoneit et al., 1988).

some of the larger organics associated with petroleum that have been observed in tropospheric particles (Simoneit et al., 1988).

A particularly interesting example of direct emissions of particles into urban areas is that from cigarette smoke. Figure 9.47 shows the concentrations of some long-chain alkanes found in cigarette smoke (Fig. 9.47a) as well as from abrasion of leaves characteristic of the Los Angeles area (Fig. 9.47b) (Rogge et al., f994). The "/" refers to the iso (i.e., 2-methyl) isomers while the "a" refers to the anteiso (i.e., 3-methyl) isomers. The distribution is quite different in cigarette smoke, with the i-C3, and a-C32 isomers being about equal in cigarette smoke but not in the leaf abrasion products.

Green leaf abrasion products ^ Dead leaf abrasion products □

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