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PRACTICAL WORK №4

DISPERSION OF TOXIC SUBSTANCES INTO THE ATMOSPHERE

1 OUTCOMES
Become familiar with the methodology of calculation of dispersion of
harmful substance.

2 DURATION OF CLASS
The class duration is two academic hours.

3 BASIC THEORY
The main sources of air pollution are industrial plants and vehicles. A
considerable part of pollutants is released into the air from the territories occupied
by industrial and household residues. Also, pollutants came from heating systems,
livestock farms (animal husbandry complexes) and other man-made objects that
are related with human activities.

Typical features of the contaminants are their high content in places with
large concentrations of population. In addition, these substances tend to
accumulate mainly in the lower layers of atmosphere and in the area of human
activity.
The degree of hazard depends on the ability of a substance (or compounds
which it forms) adversely affect human health and nature in general. Only when
the dispersion of pollutants, that are emitted into the atmosphere by industrial
plants, have place and their concentration drops to the value that not exceeds
science-based standards, their presence in the atmosphere has almost no effect on
wildlife and in particular on humans.
While implementing eco-engineering experiments, the main focus is on the
determining of the concentration of toxic substances, which are released into the
atmosphere by factories and plants. In terms of the behavior of smoke clouds five
main forms of smoke plume can be identified. Wavelike shape, which is
characterized by a large opening angle and a significant degree of turbulence. The
contacting of the smoke clouds with the ground and also the point of maximum
concentration of toxic substances at the breathing level are much closer to the
smokestack. Conical shape has a cone in the horizontal axis. The jet contacts the
ground at a greater distance than in the first case. Spray (Fanlike) form gives quite
a little dispersion in the vertical direction and dispersion of toxic components
occurring in a horizontal direction. Touching the earth does not occur, or occurs
very far from the pipe. Upraised form is characterized by huge concentration at the
upper boundary of the inversion layer. Harmful substances are directed to the
upper layers of atmosphere and practically do not penetrate into the earth's surface.
Smoking form is the most dangerous for low chimneys. This form corresponds to
the spread of smoke clouds near the earth's surface. A smoke cloud is located near
the chimney. The behavior of the smoke cloud is entirely dependent on the state of

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