Geoscience Reference
In-Depth Information
Table 5.2.
Nontrivial sources of major components of aerosol particles
Fossil fuel
Fossil fuel
and metal
Biomass
combustion for
combustion
Sea spray
Soil dust
Volcanic
and biofuel
transportation
for industrial
emissions
emissions
emissions
burning
and energy
processes
√
√
√
√
Black carbon (C)
√
√
√
√
√
√
Organic matter (C,H,O,N)
√
√
√
Ammonium (NH
4
+
)
√
√
√
√
√
Sodium (Na
+
)
√
√
√
√
√
Calcium (Ca
2
+
)
√
√
√
√
√
Magnesium (Mg
2
+
)
√
√
√
√
√
Potassium (K
+
)
√
√
√
√
√
√
Sulfate (SO
4
2
−
)
√
√
Nitrate (NO
3
−
)
√
√
√
√
√
Chloride (Cl
−
)
√
√
√
√
Silicon (Si)
√
√
√
√
Aluminum (Al)
√
√
√
√
√
Iron (Fe)
particles. These sources are discussed in more detail
later in the chapter.
is sea salt, most of which is sodium chloride. Table 5.3
shows the relative composition of the major constituents
in sea water. The chlorine-to-sodium mass ratio in
sea water, obtained from the table, is about 1.8 to 1.
Although organic carbon comprises only a small per-
cent of total sea spray mass worldwide, it comprises an
increasing percentage of particle mass with decreasing
size in phytoplankton blooms (Facchini et al., 2008).
When sea water is emitted as sea spray or spume
drops, the chlorine-to-sodium mass ratio, originally
1.8:1, sometimes decreases because the chlorine is
removed by sea spray acidification (e.g., Eriksson,
1960; Duce, 1969; Hitchcock et al., 1980).
Sea spray
acidification
occurs when sulfuric or nitric acid enters
5.2.1.1. Sea Spray Emissions
The most abundant natural aerosol particles in terms of
mass present in the atmosphere at a given time are sea
spray drops.
Sea spray
forms when winds and waves
force air bubbles to burst at the sea surface (Woodcock,
1953). Sea spray is emitted primarily in the coarse mode
of the particle size distribution. Winds also tear off wave
crests to form larger drops, called
spume drops
,but
these drops fall back to the ocean quickly. Sea spray ini-
tially contains all the components of sea water. About
96.8 percent of sea spray weight is water and 3.2 percent
Table 5.3.
Mass percentages of major constituents in sea water
Mass percentages
Mass percentages
Constituent
in sea water
Constituent
in sea water
Water
96.78
Sulfur
0.0876
Sodium
1.05
Calcium
0.0398
Chlorine
1.88
Potassium
0.0386
Magnesium
0.125
Carbon
0.0027
The concentration of these constituents, including water, in sea water is 1,033,234 mg/L.
Source:
Lide (1998).
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