143
snowflakes. Suspended particles with a diameter of less than 10 μm have a different
deposition path, since they have a negligible mass and are therefore more susceptible to the influence of gravity than gases. A significant part of the suspended particles is deposited by sedimentation. Dust particles are also deposited together with a
larger number of particles of lower density, such as gaseous particles (Tye et al.
2006). A different mechanism of dry deposition takes place when a particle enters
an element of air volume and, carried by the wind, reaches the ground. Instead, wet
deposition mainly occurs when particles act as nuclei of the condensation process
for water molecules that turn into rain or snow. Gases present in the atmosphere can
be removed by atmospherics, precipitation by rain, snow, and ice.
5.4 Fate of Aerosols
The fate and behavior of substances in the environment depend on the physicochemical characteristics of the substance itself and the environment in which the
observed substance is located. The atmosphere contains a significant amount of
aerosols, from droplets of fog or clouds to dust particles from the ground and smoke
from combustion, which greatly affect the fate and behavior of certain substances in
the environment. Atmospheric particles can have different physical and chemical
characteristics such as size, concentration, chemical composition, hygroscopy, density, morphology, and electrical and optical characteristics; although significant
variability in particle size has been observed, their diameter is, in most cases, a few
μm. Fine particles are emitted by combustion and form ultrafine and accumulative
particles. Ultrafine particles with a diameter, Dp, below 0.1 μm are formed in a
homogeneous atmosphere by nucleation or coagulation of smaller particles, while
accumulative particles (0.1 < Dp < 2.0 μm) are formed by condensation on smaller
particles. Large particles, larger than 2 μm, are formed mechanically, by separation
from larger solid and liquid surfaces. Aerosol concentration is most often expressed
in μg/m
3
. In rural areas, the concentration usually does not exceed 5 μg/m
3
, while in
polluted areas in urban areas, the aerosol concentration is about 100 μg/m
3
(Mackay
2001). Atmospheric aerosol originates both from natural sources, such as “sea dust,”
soil particles emitted into the atmosphere by wind, transboundary transport of dust
from the Sahara, and volcanic and biogenic emissions, and from anthropogenic
activities, such as burning fossil fuels in industry, traffic, and households. Depending
on the mode of emission from these sources, the aerosol is classified into primary
and secondary – the primary aerosol is emitted directly into the atmosphere, while
the secondary aerosol is formed by condensation, followed by coagulation, as a
result of oxidation of hydrocarbons in the atmosphere to less volatile compounds. In
air with a dominant emission of the primary aerosol, a significant amount of ultrafine particles is present, while in the air that makes up the secondary aerosol, accumulative particles coated with a liquid organic and inorganic film will dominate.
Soot emitted by diesel engines and the combustion of fossil fuels for household
heating is a source of primary organic elemental carbon in the aerosol. Elemental
5 Proposing Chemometric Tool for Efficacy Surface Dust Deposition Tracking…
snowflakes. Suspended particles with a diameter of less than 10 μm have a different
deposition path, since they have a negligible mass and are therefore more susceptible to the influence of gravity than gases. A significant part of the suspended particles is deposited by sedimentation. Dust particles are also deposited together with a
larger number of particles of lower density, such as gaseous particles (Tye et al.
2006). A different mechanism of dry deposition takes place when a particle enters
an element of air volume and, carried by the wind, reaches the ground. Instead, wet
deposition mainly occurs when particles act as nuclei of the condensation process
for water molecules that turn into rain or snow. Gases present in the atmosphere can
be removed by atmospherics, precipitation by rain, snow, and ice.
5.4 Fate of Aerosols
The fate and behavior of substances in the environment depend on the physicochemical characteristics of the substance itself and the environment in which the
observed substance is located. The atmosphere contains a significant amount of
aerosols, from droplets of fog or clouds to dust particles from the ground and smoke
from combustion, which greatly affect the fate and behavior of certain substances in
the environment. Atmospheric particles can have different physical and chemical
characteristics such as size, concentration, chemical composition, hygroscopy, density, morphology, and electrical and optical characteristics; although significant
variability in particle size has been observed, their diameter is, in most cases, a few
μm. Fine particles are emitted by combustion and form ultrafine and accumulative
particles. Ultrafine particles with a diameter, Dp, below 0.1 μm are formed in a
homogeneous atmosphere by nucleation or coagulation of smaller particles, while
accumulative particles (0.1 < Dp < 2.0 μm) are formed by condensation on smaller
particles. Large particles, larger than 2 μm, are formed mechanically, by separation
from larger solid and liquid surfaces. Aerosol concentration is most often expressed
in μg/m
3
. In rural areas, the concentration usually does not exceed 5 μg/m
3
, while in
polluted areas in urban areas, the aerosol concentration is about 100 μg/m
3
(Mackay
2001). Atmospheric aerosol originates both from natural sources, such as “sea dust,”
soil particles emitted into the atmosphere by wind, transboundary transport of dust
from the Sahara, and volcanic and biogenic emissions, and from anthropogenic
activities, such as burning fossil fuels in industry, traffic, and households. Depending
on the mode of emission from these sources, the aerosol is classified into primary
and secondary – the primary aerosol is emitted directly into the atmosphere, while
the secondary aerosol is formed by condensation, followed by coagulation, as a
result of oxidation of hydrocarbons in the atmosphere to less volatile compounds. In
air with a dominant emission of the primary aerosol, a significant amount of ultrafine particles is present, while in the air that makes up the secondary aerosol, accumulative particles coated with a liquid organic and inorganic film will dominate.
Soot emitted by diesel engines and the combustion of fossil fuels for household
heating is a source of primary organic elemental carbon in the aerosol. Elemental
5 Proposing Chemometric Tool for Efficacy Surface Dust Deposition Tracking…