Meaning of Thermal Pollution
Thermal pollution can be defined as the degradation of the quality of water due to a process that causes any change from the ambient temperature.
Any sudden change (increase or decrease) in the temperature of a water body, which is caused by human activities, is termed as thermal pollution.
When the quality of a natural water body degrades due to processes that bring about changes in its ambient temperature, the phenomenon is called as thermal pollution.
When increased amount of undesirable heat is added to a water body, it harms the aquatic life that lives in it. This is known as thermal pollution.
Harmful discharge of heated pollutants into any water body gives rise to thermal pollution.
Causes of Thermal Pollution
1. Discharge of heated water: Various industrial plants including petroleum and paper industries, thermal power and chemical plants, smelters and coal-fuelled as well as Hydro-electric power plants take the natural water bodies for granted and use them as coolant. They discharge tons of heated waste pollutants in water bodies, which in turn soar up the water temperature causing intense thermal pollution.
2. Domestic sewage discharge: Residential buildings that are close to natural water resources like lakes, rivers, etc. continuously drain off their domestic sewage pipelines into these water bodies. This is done on a regular basis and is one of the contributing factors towards thermal pollution. This practice is against the basic civic sense of any human being and a responsible citizen of any country.
3. Oil Spillage: This is another major cause of thermal pollution, especially in oceans. Oil spills from cargo ships or passenger ships regularly pollute marine waters. The spilled oil that is immiscible in water forms a thick layer on the surface of the water and alters the water temperature. Polycyclic aromatic hydrocarbon (PAH) is the chemical that is present in crude oil which is the major water pollutant.
4. Increased levels of water: When water levels in the natural water bodies rise up beyond their normal limit, it leads to increased exposure to sunlight. This further aids in heating up the water bodies and harming the aquatic life residing in it.
5. Geothermal activities under large water bodies: Large water bodies like oceans may have certain natural causes for thermal pollution like volcanoes and other geothermal activities. Geothermal activities taking place under these water bodies heat up the water to a significant extent (for example: heated lava).
6. Excessive destruction of forest lands: Deforestation is also a cause of thermal pollution. Trees and vegetation provide shade and prevent sunlight from directly attacking the water surfaces. However, thanks to deforestation, water bodies receive the direct wrath of sunlight and the intense exposure leads to thermal pollution. Deforestation also is a cause of global warming, which indirectly affects the water temperature as well.
7. Pollution due to urban runoff: This type of thermal water pollution is also called as storm-water pollution. When any natural calamity like flood occurs, the waste water tends to run-off from the urban roads and end up in the naturally occurring water bodies. This causes increased amount of garbage and junk in the water bodies leading to increased water temperature. Even without natural calamities, urban run-off from surfaces that are paved (roads and parking lots) regularly pollute surface waters. Summer seasons (meaning heated paved roads) sees more of thermal pollution due to urban run-off when compared to other times of the year.
Thermal pollution is one of the major causes of water pollution in general. Industrialization and urbanization comes with a cost and thermal pollution is one of its disadvantages. Precautionary measures should be taken to not treat our natural water bodies like a garbage dump. Treatment plants should be built in factories to solve this grave problem of thermal pollution. Effluent disposal methods of industries should be strictly monitored by the government or the concerned regulatory authorities to keep a check on water pollution. Thermal water pollution is a reversible phenomenon and should be stopped before it is too late.