2. Environmental Pollutants
The various types of pollutants are : Physical pollutants, Chemical pollutants and biological pollutants
They can also be classified on the basis of weather they degrade or not into : biodegradable and non-biodegradable
They are the physical , chemical or biological agents which when released into the environment adversely affect the the
human interests.
Environmentalpollution
The environmental pollution is the unfavorable alteration of our surroundings wholly or largely as a byproduct of
human actions, through direct or indirect effects of changes in energy patterns, radiation levels, chemical and
physical constitution and abundance of organisms.
The environmental pollution can be broadly classified into
1. Air pollution
2. Water pollution
3. Soil pollution
3. Air pollution (Tropospheric pollution )
Combustion Of fuels : Combustion of fuels such as coal, wood , petrol, diesel in various industries and
automobiles is the major source of air pollution.
The increase in the concentration of undesired gases and
particulate matter in the troposphere to such an extent that they
can produce undesirable effects on human beings and their
environment is referred to as air pollution or tropospheric
pollution.
Sourcesof air pollution
Industrial processes : A large number of industrial processes are also responsible for air pollution.
ve cutting of trees thus indirectly causes air pollution .
Types of Air Pollutants
Primary pollutants : The pollutants which are emitted directly from the
sources are called primary pollutants.
Secondary pollutants : The pollutants which come into existence in the
atmosphere in account of chemical reactions involving primary pollutants
are called secondary pollutants.
4. Control of Air Pollution
1. The factories should have chimneys as they reduce the concentration of air pollutants at the ground
levels.
2. The use of cyclone collector reduces the concentration of particulate matter in the atmosphere.
3. The dust particulates present in the air can be minimized by extraction ventilation.
4. The practice of reforestation can also play a significant role in reducing air pollution.
5. The use of electric vehicle and CNG automobiles can also reduce air pollution significantly.
Some major Atmosphericpollutants
1. Carbon monoxide (CO )
2. Carbon dioxide (CO2)
3. Sulphur dioxide (SO2)
4. Hydrogen sulphide (H2S)
5. Sulphur trioxide (SO3)
5. Acid Rain
The term acid rain was first introduced by Robert Angus. Acid rain refers to the presence of excessive acids in rain
water. The acids mainly present in the acid rain are sulphuric acid , nitric acid , sulphurous acid , nitrous acid ,
hydrochloric acid.
Formationof Acid Rain
Greenhouseeffect and global warming
The greenhouse effect is a process that occurs when energy from a planet's
host star goes through the planet's atmosphere and heats the planet's surface,
but greenhouse gases in the atmosphere prevent some of the heat from
returning directly to space, resulting in a warmer planet.
Global warming refers to the increasing temperature of the Earth’s climate
system and its related effects.
6. Water pollution
The presence of any foreign substance (inorganic, organic, biological or radioactive) which alters the physical ,
chemical or biological properties of water which constitutes a health hazard or decreases the usefulness of
water is termed as water pollution.
waterpollutants
1. Dissolved oxygen consuming wastes 5. Suspended particles
2. Synthetic chemicals. 6. Oil
3. Inorganic chemicals and minerals. 7. Radioactive substances
4. Pathogenic microorganisms
Measures to control waterpollution
1) Waste water treatment technology :It should be adopted before throwing water into
water bodies . The technology involves physical, chemical or biological treatment of
the waste water.
2) Dilution of waste water :The dissolved oxygen of water used for dilution causes
purification of waste water through biodegradation of organic compounds by bacteria.
3) Waste water reclamation : It helps to great deal in reducing water pollution. Sewage
water can be directly be used for irrigation. The low grade polluted water can be used for
industrial cooling. The use of sewage water will save the fresh water from getting polluted.
7. Soil pollution
The change in the fertility of the soil on account of the addition of chemical substances to the soil system in an
indefinite proportion is called soil pollution.
Soil pollutants
1. Fertilizers and pesticides
2. Domestic refuse
3. Industrial effluents
4. Soil erosion
5. Heavy metals
6. Radioactive wastes
Measures to control soil pollution
1.Use of pesticides should be minimized.
2. Use of fertilizers should be judicious.
3. Cropping techniques should be improved to prevent growth
of weeds.
4. Special pits should be selected for dumping wastes.
5. Controlled grazing and forest management.
8. Industrial pollution
Pollution whose source originates directly from industry is known as industrial pollution.
Industrial pollutants
1. Fuel
2. Isolation of raw materials
3. Transportation
4. Chemical processes
5. Solid wastes
9. Greenchemistry
Green Chemistry is the strategy of designing chemical products and processes in away that eliminates or
reduces the use and generation of substances which are hazardous to health and environment.
The green chemistry may be regarded as an alternative tool for reducing pollution. It not only aims to
eliminate toxic pollutants but also intends to change our habits and life style suitable to make a pleasant
and healthy environment.
Objectives of greenchemistry
i. It intends to reformulate the synthetic routes in such a way that harmful
pollutants are either nor produced or do not enter into the atmosphere.
ii. It aims to design isolated methods for obtaining raw materials in such a
way that the environments is least affected.
iii. It aims to modify the existing industrial processes in such a way that
they
use or produce materials of low or no toxicity.
iv. It aims to produce green chemicals and materials which would be
friendly to the environment.
v. It aims to use the renewable sources of energy in place of depletable
sources as far as possible.
