does pollution actually mean ?
Pollution is the addtion of a substance that alters
our environment and harmfully affects the living organisms.
The substance which does so is called pollutant.
Nature Of Pollutants:
Bio-degradable : These are organic substances
which are decomposed by the action of micro organisms.The
pollution is thus negligible.These cause pollution when
they occur in large quantities such that the microorganisms
are unable to decompose them.
Non Bio-degradable:- Substances
like iron,lead,aluminium,plastic etc. do not decompose or
even if they do they do so at a very slow rate.These keep
accumulating and thus causing pollution.These enter our
bosy through food etc.
Water Pollution :
The living organisms require water .Humans need water for
various purposes such as irrigation,domestic,industrial
etc. But unmanaged use of water resources has lead to its
pollution causing various diseases like cholera,typhoid,jaundice,diarrhoea
etc. Water pollution has been caused due to some of the
1. Sewage and Domestic Wastes
Kitchen waste is referred to a garbage wheras other
domestic waste is referred to as sewage.Sewage and
garbage like rotting fruits and vegetables etc. are
dumped into the water resources and they use up oxygen
dissolved in water for they decay. Even the aquatic
plants and animals require oxygen for their vital
functions but due to pollution it leads to deficiency
of dissolved oxygen.
Eutrophication : -
Due to increased amount of nitrates in slow moving
water , algae growth takes place. After a while these
algae die and fall to the bottom of the lake. For
their decay Oxygen is used up again leading to the
deficiency of oxygen for aquatic organisms.
2. Effect of pesticieds and agricultral
Pesticides from agricultural run off , metals and processed
chemicals from industries etc. enter the food chain of the
aquatic animals leading to disastrous consequences.The toxic
substances accumulate in the body of fishes which are eaten
by man and other animals.These chemicals thus reach the
human body which cause various diseases and sometimes even
3.Effect of Oil Spills :-
These are perhaps the most dangerous water pollutants
of the ocean. By accident or purposely millions of tonnes
of oil is deposited in the ocean every year which causes
extreme harm to aquatic life.
|Air Pollution :
In cities and industrialised zones the effect
of air pollution is becoming more and more widespread.This
is caused due to increased amounts of gases like Sulphur
dioxide , carbon monoxide , oxides of nitrogen etc .
These are a health hazard. The chief causes are automobiles
, industries, volcanic wastes , thermonuclear explosions
, burning of wastes etc.
1. Effect of Industrial and domestic wastes : -
Industrial fumes carry both solid as well as gaseous
pollutants. The solid components include soot , fine metabolic
particles and varying amounts of hydrocarbons. Soot forms
the nuclei on which the water vapour condenses to form smoke
haze and fog. Smog is a thick persistent fog that is formed
when polluted air cannot rise due to air layers of different
temperatures that hang over a city.
Sulphur dioxide is the most harmful gaseous pollutant.
It readily dissolves in water to form acids that kill plants
and damage buildings(acid rain). The acidity of the soil
is increased ,leading to loss of nutrient ions.
It is formed during the putrifaction of animal
and vegetable substances containing sulphur. It is also
created in petroleum refineries and volcanoes. It has the
smell of rotten eggs. It takes up the oxygen from the blood
to form iron sulphide. Thus it reduces the oxygen content
in the blood.
Lead is also added to petrol to make car
engines run better. Breathing lead polluted air can cause
brain damage. However now the use of unleaded petrol is being
They also release soot .Variety of other gases
such as sulphur dioxide,nitrogen dioxide,carbon monoxide
and hydrocarbons. Carbon monoxide
formed due to incomplete combustion of hydrocarbons
is a very poisnous gas.It combines with haemoglobin
to form carbamino-haemoglobin.It is a permanent componud
and thus it robs the blood of haemoglobin. Death
is by asphyxiation.
3.Soil Pollution :
Nitrogen is an essential constituent of all living
cells. Nitorgenous compounds are taken up by the plants
as they cannot take in atmospheric nitrogen directly.
Soil erosion also causes much damage.The
fertile top soil is bound by the roots of grasses and trees.
Excessive grazing and deforestation has lead to an excessive
loss of this fertile top soil by various agents of erosion
like wind , water , etc.
|Nitrogen cycle helps
to maintain soil fertility.Soil bacteria play an important
role in this cycle.However excessive use of fertilizers
and pesticides reduce the ability of bacteria to decay
wastes and produce nutrients naturally.Acid rain increases
the acidity of the soil.
Fertilizers are chemical substances that are added
to the soil to increase its fertility and thereby increase
the crop production.Those of natural origin are called natural
fertilizers and those which are artificially made are called
Bio- Fertilizers are preferred to Chemical Fertilizers
1. Chemical fertilizers are expensive.
2.Their production releases pollution.
3.Their production depends on exhausting sources of energy
such as petroleum , coal etc.
4.They are lost as surface run off and pollute soil and
The Greenhouse Effect The burning of coals
and oils release carbon dioxide into the air which is used
by plants for photosynthesis. Indiscriminate deforestation
upsets this balance.Normally the heat received by the Sun
is radiated . But excessive carbon dioxide traps the heat
just like in a green house in which the heat can enter but
It leads to rising of global temperatures and can also
lead to melting of ice at the poles which will lead to rise
in levels of water in all the water bodies .This can flood
small islands and cause danger to their existence.
|Ozone Layer Depletion : -
About 15 to 50 km above the earth is the ozone layer
which protects us from the harmful UV rays of the Sun.Scientists
had discovered a hole in it in the 1980's above Antarctica
as big as the United States. There are other smaller
joles as weel. A record size hole was found this October.These
holes are caused due to certain chemicals called CFC's
or Chloro Fluoro Carbons.These are contained in aerosol
cans ,deodorants,Rerigerators. etc.
The Future Of The Earth Lies In your Hands.