this is a good notes for pollution .

2.  The presence of extremely high concentrations of harmful
substances in the environment is known as pollution.The major
kinds of pollution causing health hazard today are air, water, and
soil pollution.
 When certain human activities pollute environmental media such
as air, water or soil such that they are harmful to the health of
living organisms in the environment, we say that the environment
is polluted.
 Any unwanted or harmful substances which pollute the
environment are called pollutants. Generally, certain harmful
substances like carbon dioxide, carbon monoxide, and nitrogen
dioxide are usually present in the air in small quantities and they
are not harmful to us. But when these substances are present in a
more quantity which cannot be tolerated, they become pollutants.

4.  The presence of harmful or excessive toxic compounds in air
results in air pollution.
 The main sources of air pollution are harmful gases like sulfur
dioxide, carbon dioxide, carbon monoxide, nitrous oxide, nitrogen
dioxide, and other suspended particles.
 Air pollution is usually caused by the burning of fossil fuels like
petroleum and coal, burning of wood and cow dung cakes in
homes, factories, vehicles and power plants. Among all other
continents in the world, India is the country having the most
number of polluted cities. Lucknow, Kanpur, New Delhi are few
among them and this is because of excessive use of fossil fuels by
vehicles and other industrial units.

6.  The contamination of water bodies such as lakes, rivers, oceans,
underground water and seas by harmful substances is known as
water pollution.
 Polluted water becomes unfit for drinking, bathing, washing,
and irrigation.

 The main cause of water pollution is sewage, industrial wastes,
pesticides and fertilizers from farming.Garbage dumping can also
leak out pollutants into underground water.
 The major pollutants of water are usually lead, mercury, fertilizer
and pesticide compounds.The major source of pollution of the
Ganga River is sewage and industrial wastes from tanning
factories.

8.  Soil pollution is the contamination of soil due to harmful
substances.
 Polluted soil becomes unfit for growing crops and plants and is
usually accompanied by water pollution.
 The major causes of soil pollution are over irrigation, usage of
pesticides, dumping of sewage and garbage, deforestation and
mining.
 The most common soil pollutants are heavy metals like lead and
mercury, pesticide compounds, salt and mineral ores.These
pollutants disturb the soil profile, which results in spoiling the
fertility of the soil and makes it unfit for growing crops

10. Effects of Environmental Pollution:
It has been seen that pollutants originate at a point and are then
transported to other places by the action of wind or water.
Some pollutants are dumped into the soil by human beings.This
leads to air, water and soil pollution respectively.
If the soil is polluted, the useful microorganisms in it will die and the
fertility of soil will be lost.The production of crops will decrease. If the
soil is not fertile; it will have a harmful impact on the human society.
Similarly, if water is polluted then we have to purify it before drinking.
Purification needs resources.
 Lastly, if air is polluted, respiration will become an issue and
survival of life will be under threat.Air pollutionleads to many
respiratory diseases and harms the human body.

12.  Fuel substitution is another way of controlling air pollution. In many parts
of India, petrol and diesel are being replaced by CNG – Compressed
Natural Gas fuelled vehicles.
 Another way of controlling air pollution caused by industries is to modify
and maintain existing equipment such that pollutants are minimized.
 There are certain chemical methods which help in the control of water
pollution such as the ion exchange process, reverse osmosis,
precipitation, coagulation.As an individual, reducing, reusing and
recycling wherever possible will go a long way in reducing the effects of
water pollution.

14.  The very first superbug was created to degrade
oil in 1970s when Chakrabarty and co-workers
reported the development of a new strain of
bacterium by transfer of plasmids and named it
superbug which could utilize a number of toxic
organic chemicals like octane, hexane, xylene,
toluene, camphor and naphthalene. In 1980,
United States granted the patent to this
superbug making it the first genetically
engineered microorganism to be patented.

15.  The electrostatic precipitator works by removing particles and
smoke from a gas stream using an electrostatic charge.
 Dust particles travel past wires that have a high direct current (DC)
voltage applied, which ionises the surrounding gas.This corona
discharge causes the particles to pick up a small electrostatic
charge.
 An oppositely-charged plate attracts the particles, neutralises and
retains them. A regular tapping (rapping) of the plates then
physically removes the collected particles.
 Introducing a water spray can reduce the electrical resistance of
the dust particles, allowing them to accept the charge more easily.