Thermal-Pollution-PPT.pptx

Thermal-Pollution-PPT.pptx

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  Submitted To: www.studymafia.org SubmittedBy: www.studymafia.org Thermal Pollution www.studymafia.or g
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  • Thermal Pollutionis the harmful increase in water temperature in streams, rivers, lakes, or occasionally, coastal ocean waters. • It is the degradation of water quality by any process that changes ambient water temperature. • A temperature increase as small as 1 or 2 Celsius degrees (about 2 to 4 Fahrenheit degrees) can kill native fish, shellfish, and plants, or drive them out in favor of other species, often with undesirable effects.
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  It occurs whenan industry removes water from a source (e.g., a river), uses the water for cooling purposes, and then returns the heated water to its source. Power plants heat water to convert it into steam, to drive the turbines that generate electricity. For efficient functioning of the steam turbines, the steam is condensed into water after it leaves the turbines. This condensation is done by taking water from a water body to absorb the heat. This heated water, which is at least 15 degrees celsius higher than the normal, is later discharged back into the water body.
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  The major sourcesof thermal pollution are discharge of heated water or hot waste material into water bodies from  Nuclear power plant  Industrial effluents  Domestic sewage  Hydro-electric power  Coal fired power plants  Thermal shock Other causes are :  Deforestation  Soil erosion
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   Nuclear powerplants use water as a cooling agent.  After the water is used, it is put back into a water supply at 9-20oC warmer .  Emission from nuclear reactors increase the temperature of water bodies.
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   Coal isutilized as a fuel.  Condenser coils are cooled with water from nearby lake or river.  The heated effluents decrease the DO of water.  Damages the marine organisms.
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   Discharged waterfrom steam-electric power industry using turbo generators will have a higher temperature ranging from 6 to 9˚C than the receiving water.  In modern stations, producing 100 MW, nearly one million gallons are discharged in an hour with increase in temperature of the cooling water passing by 8 to 10 ˚C .
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   Sewage iscommonly discharged into lakes, canals or streams.  Municipal sewage normally has a higher temperature than the receiving water.  Increase in temperature of the receiving water decreases the dissolved oxygen of water.  The foul smelling gases increased in water resulting in death of marine organisms.
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   Generation ofhydro electric power sometimes results in negative thermal loading in water systems.  Creates less heat on water sources less than nuclear power plant.
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  When a powerplant first opens or shuts down for repair or other causes, fish and other organisms adapted to particular temperature range can be killed by the abrupt change in water temperature known as "thermal shock."
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   Streams andsmall lakes are naturally kept cool by trees and other tall plants that block sunlight. People often remove this shading vegetation in order to harvest the wood in the trees, to make room for crops, or to construct buildings, roads, and other structures.
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   Removal ofvegetation far away from a stream or lake can contribute to thermal pollution by speeding up the erosion of soil into the water, making it muddy, which increases the light absorbed .
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  • Elevated temperaturetypically decreases the level of dissolved oxygen of water. • Increases the metabolic rate of aquatic animals, as enzyme activity, resulting in these organisms consuming more food in a shorter time , which increases their need for oxygen. • High temperature limits oxygen dispersion into deeper waters, contributing to anaerobic conditions.
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  • This leadto increased bacteria levels when there is ample food supply. Many aquatic species will fail to reproduce at elevated temperatures. • Primary producers are affected by warm water because higher water temperature increases plant growth rates, resulting in a shorter lifespan and species overpopulation.
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   Energy chips Desalination plants  Less nuclear power  End shoreline deforestation  Prevent soil erosion