What is thermal pollution?

Thermal pollution is a type of environmental pollution produced by him increase or decrease in the temperature of the mediumwhether soil, air or water, although the most frequent type by far is the increase in temperature in masses and water courses.

Although it may or may not be related to global warming of the planet, thermal pollution is usually referred to as a much more localized areafor example, the increase in the temperature of a lake due to the discharge of hot water from a nearby factory.


Increased water temperature

A common source of thermal pollution is hot water discharges from cooling systems of thermal power plants, nuclear power plants and other industrial processes.

For example, nuclear power plants use the heat released from nuclear fission reactions to produce electrical energy. The yield is not 100%, but is frequently below 50%, depending on the type of reactor. The rest of the energy is released in the form of heat and water is used as a coolant, as it is cheap, highly available and effective in dissipating heat. For this reason, nuclear power plants are often close to rivers, lakes and seas.

To avoid the problem of thermal pollution of this type, the water is passed through towers or evaporation zones before being discharged into the environment. Although this method lowers the temperature considerably, it produces other detrimental effects, for example the increased salt concentration or the alteration of other physicochemical properties of the water.

Another common source of thermal pollution in water is urban runoff during hot seasons. Pavements reach high temperatures heated by the Sun and can have a very significant impact on the heating of small riverbeds in the event of rains and storms.

To prevent thermal pollution from urban runoff, different methods can be used, such as bioretention systems, infiltration ponds or, less effectively, retention ponds.

ecological effects

Gases are less soluble in hot liquids, so increasing water temperature causes decrease the amount of dissolved oxygen. Even if a very high temperature change does not occur, it can have a strong impact on the aquatic lifeincluding fish, amphibians, plants, algae, microorganisms or insects.

The rise in temperature can also increase metabolic rate of some organisms, such as some bacteria or types of algae, which can develop a overpopulation with negative effects on the ecosystem; For example, an overpopulation of algae can consume almost all the oxygen in the water and cause changes in the food chain that result in a decline in biodiversity.

Other organisms, on the contrary, can suffer metabolic alterations that result in a higher mortality rate or reproductive problemswhich would also contribute to the decrease in biodiversity.

The increase in temperature in bodies of water close to human populations can directly affect their health. For example, it can increase the risk of transmission and incidence rate of certain diseases, for example Tropical diseases.

Drop in water temperature

In some cases, the opposite may occur and colder water discharges may occur. For example, it is very common for the release of water from reservoirs and reservoirs to take place in lower sinks, which causes water to be released from the colder layers. This effect can be mitigated with alternative reservoir designs.

thermal shock

When there are drastic or rapid changes in the temperature of the environment, the habitat can suffer a thermal shock. Fish, plants and many other organisms can disappear or leave the area in a short time.

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