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Answers
Answer:
1. Environmental Degradation
Environmental degradation means the deterioration of the environment via various ways. It affects the basic functions of the ecosystem like supporting life forms, provision of resources, protection etc. Environmental degradation includes pollution, depletion, global warming, biodiversity loss etc.
2. Pollution and Pollutants
2.1 What is environmental pollution?
Pollution is any undesirable change in physical, chemical or biological characteristics of the environment.
2.2 Different types of pollution
On the basis of the which sphere of environment is affected by pollutants, pollution is classified into
Air pollution
Water pollution
Land pollution
Marine pollution
Radiation Pollution
Thermal Pollution
Noise pollution etc
2.3 Different pollutants
Pollutants are any substance that causes pollution. They can be
Gases (ex- SO2, NO2)
Particulate matter (ex- PM10, PM2.5) [FAQ 1]
Radioactive substances (ex- radium, thorium, uranium). They can be from nuclear reactor accidents, nuclear bomb explosions or from radiations in nuclear reactors, laboratories, hospitals etc
Bio wastes (ex- food waste, agricultural residues)
Non biodegradable substances (ex-plastics)
Persistent chemicals (ex- DDT)
Heavy metals (ex – Mercury, Lead )
3. Air Pollution
Air pollution is mainly due to gaseous pollutants like NO2 and particulate matter like dust. The main sources of pollutants are exhaust from combustion engines, fires, dust from dry land and construction activities
3.1 Types of pollutants
Primary pollutants Secondary Pollutants
Directly produced from sources like combustion engines
Gases Particulate matter
SO2
H2S
NO2
Hydrocarbons
Suspended Solid particles like dust
Liquid particles like Aerosols
Biological agents like pollen and spores
Metals like Pb,Cu,Hg
Are formed because of reaction of primary pollutants
Eg:
Smog
Photochemical smog
Ozone
Acid rain
Particulate matter
Particulate matter suspended in air are dust and soot(released from the industrial chimneys)
Fly ash[FAQ 2] is a particulate ejected mostly by thermal power plants during coal burning operations
Effects of Fly ash pollution
Fly ash pollutes air and water and may cause heavy metal pollution in water bodies
Fly ash affects vegetation as a result of its direct deposition on leaf surfaces or indirectly through its deposition on soil
Fly ash utilisation
Fly ash is now being used for making bricks and as a land fill material
Lead and other metals particles Tetraethyl lead (TEL) used as an anti-knock agent in petrol vehicles comes out from the exhaust pipes and is mixed with air.
Oxides of iron, aluminium, manganese, magnesium, zinc and other metals are released during mining operations
Aerosols
Are suspensions of solid or liquid particles in a gas (The particulate portion of an aerosol is referred to as Particulate Matter)
The aerosols are of following types
Solid-Particle Aerosols – Includes dust and fume(Fumes are solid particles formed by condensation from the gaseous state)
Liquid-Droplet Aerosols – Includes Mist and fog
Solid-Liquid particle Aerosols – Includes smoke(is a collection of tiny solid, liquid and gas particles) and smog(smoke + fog)
Main sources of aerosols are half-burnt carbon particles from vehicle exhausts or crop residues. Natural sources are fog and haze.
Effect on meteorology – Aerosols shield the solar radiation and depress the land temperatures. This causes variations in the monsoon rain pattern.
Smog
It is a mixture of smoke, fog and sulphur dioxide.
Chemically it is a reducing mixture and so it is also called as reducing smog.
It occurs in cool humid climate.
Photochemical Smog
It occurs in warm, dry and sunny climate.
The main components of the photochemical smog result from the action of sunlight on unsaturated hydrocarbons and nitrogen oxides produced by automobiles and factories.
Ozone and NO2 react with the unburnt hydrocarbons to produce chemicals such as formaldehyde, acrolein and peroxyacetyl nitrate (PAN).
Photochemical smog has high concentration of oxidising agents and is called as oxidising smog.
Usually catalytic converters are used in the automobiles, which prevent the release of nitrogen oxide and hydrocarbons to the atmosphere.
Ozone
Ozone in the troposphere is a potential green house gas
It is a key component of the photochemical smog
Acid Rain
Is a precipitation having a pH less than 5.6
Acid can precipitate either as rain or as dry deposition
Contains traces of H2SO4, HCl and HNO3
When rain water and oxygen combines with sulphide bearing minerals like pyrite (iron) they form sulphuric acid
Effects of acid rain
Acid rain affects the buildings and monuments. Marble and various
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