Geoscience Reference
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(a)
(b)
(c)
(d)
Figure 5.6.
Scanning electron microscopy images of (a) an ash aggregate, (b) a combusted plant fiber, (c) an
elongated ash particle, and (d) soil dust particles collected from forest fire emissions in Brazil by Reid and
Hobbs (1998).
than 1
mindiameter. Fly ash is generally found in
particles larger than 1
mindiameter. POM is emitted
in both size ranges.
Coal combustion results in the emission of soot,
POM, sulfate, and fly ash. The fly ash consists of oxy-
gen, silicon, aluminum, iron, calcium, and magnesium
in the form of quartz, hematite, gypsum, and clays.
Combustion in gasoline engines usually results in the
emission of submicron POM, sulfate, some soot, and
elemental silicon, iron, zinc, and sulfur. Combustion in
diesel engines usually results in the emission of these
components, plus more soot and ammonium.
Diesel-powered vehicles without particle control
devices (
aftertreatment technologies
)emit10to100
times more particle mass than do gasoline-powered
Figure 5.7.
Grass fire, February 28, 2009.
C
Fairiegoodmother/Dreamstime.com.
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