Biogenically Derived. Organics in Aerosol Particles

FIGURE 9.43 Concentrations of n-alkanes as a function of carbon number from (a) a particle sample collected in Jos, Nigeria (the dashed line represents the estimated concentrations from fossil fuel sources), (b) vegetation wax in the Jos area, and (c) particles collected over the Atlantic Ocean (adapted from Sinioneit et al., 1988). 

Two other characteristics of organics in particles are also used to differentiate biogenic from anthropogenic 

Similar biogenic organics and their distributions have been noted in a variety of locations, including the Amazon, China, and over the south Atlantic area (e.g., see Simoneit et al., 1990, 1991a, 1991b). They are also found in urban areas but generally comprise a small fraction of the total aerosol mass for example, they are about 1-3% of the total fine particulate matter in the Los Angeles area (Hildemann et al., 1996). 

Some monounsaturated fatty acids such as Clfi 1 and C1X 1 (the first number is the number of carbon atoms and the second number is the number of double bonds) are also produced biogenically, in addition to some diunsaturated species (e.g., see Sicre et al., 1990a). However, because they react fairly rapidly with tropospheric gases such as 03, OH, and NOv their concentrations are highly variable and also dependent on storage conditions after sampling. A variety of dicar- 

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