THERMAL POLLUTION1

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Atmospheric pollution in terms of changes in

temperature of the surrounding atmosphere

due to release of hot vapours from nuclear power

plants, industrial effluents, domestic sewage, etc., istermed as thermal pollution.


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1:Power Plants:

Coal fired power plants constitute the major source of

thermal pollutants. Their condenser coils are cooledwith water from nearby lakes or rivers and discharge

hot water back increasing water temperature.


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2:Industrial Effluents:

Industries generating electricity requires huge

amount of cooling water for heat removal.Other industries like textile, paper, e.t.c.

release heat in water. This hot water enters into

the rivers, canals thereby raising the

temperature.


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3:Cooling Towers:

In the evaporative-type cooling tower, warm

water is allowed to fall over large surface areas

while natural or forced air drafts cause

evaporation and cooling to occur. Heat energy

released from cooling towers in the atmospherecause thermal pollution.


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4:Domestic Sewage:

It is usually discarded into rivers, lakes or

canals with or without waste treatment whichincreases water temperature.


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5:Due to combustion of coal and petroleum

products, the CO2 concentration in the

atmosphere is raised and thereby earths

temperature increases.


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1:Life Span:

Increase in temperature of water decrease the

life of aquatic organisms.Daphnia can have a lifespan

of 108 days in 8C but its life

span at 28C is only 29 days.


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2: Respiration:

Raising temperature of rivers cause lowered

dissolved oxygen because of lower solubility ofoxygen at higher temperature which affects the

rate of respiration of fish. The oxygen

consumption for most fish becomes four-fold as

the temperature of water is raised to themaximum at which they are able to survive.


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3:Reproduction:

Rise in temperature due to thermal pollution cause

health hazards in terms of their biological activitiessuch as reproduction, nest building, hatching, etc.

A rise in temperature also decreases the

time taken by fishs eggs to hatch. Excessive

temperature, however, retard the normal

development of eggs.

Above a level of temperature fish fails to

reproduce.


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4:Food chain:

In oxygen rich water bacteria, protozoa's and

microorganism multiply rapidly becoming foodfor aquatic creatures. Thus, decrease in

dissolved oxygen due to thermal pollution

decreases bacteria, protozoas and

microorganism which affects food chainprocess.


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5:Atmosphereic temperature:

Due to thermal pollution, the average

temperature of cities is almost 10c greaterthan that of villages.


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6:Morphology:

Temperature differences during growth and

development give rise to morphologicalchanges in aquatic organisms. A variety of fish,

under the influence of thermal pollution, show

agape jaws and eye abnormalities.


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7:Increased vulnerability to disease:

Activities of several pathogenic micro-organisms get accelerated by higher

temperature of water which increases diseases.

The bacteria Chondroccusis believed to beresponsible for the massive kills ofBlue Black

Salmon.


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1: Cooling towers:

Appropriate cooling towers are to be employed to

reduce temperature. The hot water released fromindustries should be passed through these cooling

towers to control temperature.


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2:Artificial lakes:

Man-made lakes should be used for cooling

hot water released from industries.


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3:Improved electric generating plants:

The efficiency of electrical energy productive

machines should be increased to convert heatinto electricity.


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4:Warm-water irrigation:

A promising idea that is being investigated in

several places is warm water irrigation in the

hopes of stimulating and enhancing plant

growth and protecting fruit trees from killing

frosts(freezing temperature).


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5:Heating of buildings:

In winter or cold places exhausted steam is

being used to heat buildings such as institutionhaving own power plants. It would be of no use

in summer when the thermal pollution has

been likely to be worse due to heavy

production of electricity for air conditioning.


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THERMAL POLLUTION1