Analysis of
Thermal Pollution from the Air
CARL H. STRANDBERG, Project Director
General Research and Development, Inc.
Arlington, Virginia
Under U. S. Public Health Service Research Grant WP-181, extensive
research and study is being conducted to gain a better understanding of the
dispersion and diffusion of heated coolant water. Aerial photographic interpretation techniques are being used, for analyzation of heat-induced secondary effects in the aquatic environment.
Preliminary studies have confirmed that, under certain circumstances,
large areas within heated coolant water discharge zones extending from industrial outfalls exhibit distinctly different tonal characteristics. Correlation
data examined to date indicates that the water in these areas is warmer than
the surrounding water mass.
Studies have included extensive analysis of several of the factors which
may contribute to the formation of photographically recorded "secondary"
imagery, which can be recorded in the visible and near-infrared regions of
the spectrum. Analyses were also made of several types of infrared sensors
which may prove suitable for analysis of temperature distribution within the
aquatic environment.
A concept has been developed for the integration of a non-image-forming infrared sensor with a camera system, under which the infrared sensor will
act as the "triggering" unit, activating cameras when preselected thermal
limits are sensed in a water mass. On completion of the "Integrated Aerial
Sensor System," it is hoped that accurate isothermal maps may be rapidly
compiled of surface waters.
THE THERMAL POLLUTION PROBLEM
An estimated 40 per cent of all the water available in this country at any
one time is used for industrial cooling (1). Industrial expansion forcasted to
take place between now and 1980 is expected to increase this demand 240 per
cent. As we recognize, thermal cooling is a largely non-consumptive use of
water. Most of the surface water used for cooling is returned to the lake or
stream from which it was taken, carrying with it the heat acquired in the
course of its use.
The impact of heat on the aquatic environment induces many changes.
Some of these may be desirable, some of them may be  undesirable.
Thermal electric power plants are the largest single user of water for
cooling. They are estimated to use 74.5 per cent (2) ofthe total industrial
coolant water demand. Their requirements in 1959 amounted to over 24
trillion gals (3). Thermal electric plants, on the average, heat the coolant
water 12 to 13 F, before returning it to the source from which it was withdrawn.
Extensive evaluation of thermal pollution has been made in previous
studies, largely assessing its effects from the standpoints of conservation,
natural stream purification, and water loss.
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