Atmospheric pollution caused by coal-fired power stations and motor vehicle engines.

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Atmospheric Pollution Caused by Coal-Fired Power

Stations and Motor Vehicle Engines

        Photochemical smog is a mixture of chemicals which form in

the troposphere region of the atmosphere. This smog consists of

two groups of chemicals known as primary pollutants and

secondary pollutants.

(fig 1)

      As fig 1 shows primary pollutants being produced from

various sources, the main producers of primary pollutants are

motor vehicles and coal fired power plants. These produce many

pollutants such as Nox, VOCs and CO

        These primary pollutants react when given the correct

conditions to form the secondary pollutants such as O3, NO2,

H2O2, HNO3 and oxides of the VOCs.

        Many of the primary pollutants formed in a coal fired power

plant these are listed below:

 

*        Nox - formed at high temperature and pressure of the combustion

causes the atmospheric nitrogen and oxygen to react.

*        VOCs (Volatile Organic Compounds) - produced when unburnt

hydrocarbons are released through the chimney of the furnace.

*        CO - carbon dioxide is a by product of incomplete combustion.

         For photochemical smog to form there must be anticyclonic

conditions, this means high pressure, in the lower troposphere

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above a source of primary pollutants. In such condition the air at

ground level is normally very still this causes the pollutants to get

trapped near to ground level. Also sunlight is needed because in

some of the reactions a photon of electromagnetic radiation is

needed to give the molecule the energy that it needs to break its

bonds*1. These reactions are know as photochemical reactions

and are represented by the symbol hv this is derived from the

formula E=hv where E is the energy (in this case needed to brake

the ...

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