5 Pollution and its Factors part 2
Sources of Water Pollution
(i) Domestic sewage
This includes household’s wastes like food wastes, synthetic detergents used for washing
clothes and cleaning bathrooms and latrines and water based paints.
(ii) Industrial effluents
The industrial wastes are discharged in the adjoining rivers and streams through flush
lines of factories. The textiles, sugar and fertilizers factories, oil refineries, drugs manufacture,
rubber, and rayon fibers, the paper industries and the chemical factories all produce Chemical
pollution.
(iii) Agricultural source
Increased use of fertilizers has become essential for high yielding crop plants. Excess
of nitrates used as fertilizers seep into ground water is carried into lakes and pond. On
entering the drinking water supply system these create several health problems.
(iv) Pesticides
These include insecticides, fungicides, nematicides, rodenticides, herbicides and soil
fumigants. These contain chlorinated hydrocarbons, organophosphates, metallic salts,
carbonates, acetic acid derivatives etc. many pesticides are non-degradable. They pass through
the food chains and accumulate in fatty tissues thus causing several health hazards.
(v) Thermal pollution
Power plants and nuclear power stations are the main sources of thermal pollution of
water where water is used for cooling and becomes hot. The hot water on entering the main
water body raises its temperature, which kills fishes and other aquatic animals and increases
the rate of respiration in aquatic plants.
(vi) Pathogenic organisms
Sewage and domestic waste from houses introduces pathogenic organisms viz., protozoa,
worms-eggs and bacteria into water. This contaminated water if consumed causes jaundice,
typhoid, dysentery, cholera, tuberculosis etc.
(vii) Mineral oils
Oil from oil spills and washings of automobiles finds way into river water through
sewers.
(viii) Underground water pollution
Underground water particularly in cities and industrial areas is no more pure and safe.
The sources of underground water pollution are sewage, seepage, pits, industrial effluents,
septic tanks, fertilizers and pesticides, garbage etc.
(ix) Marine water pollution
River and stream network sources of water ultimately end up ocean and seas. Thus,
these acts as the sink of all natural and man-made water based pollutants. The main
sources of oceanic pollution are discharges of oil, greases, petroleum products, detergents,
sewage and garbage including radioactive wastes.
Effect of Water Pollutants
The main effects of water pollutants are:
1. Compounds of mercury, arsenic and lead are poisonous and chemically harmful as
they even affect water treatment plants e.g. organic sulphur compounds interfere
with nitrification.
2. Mercury when dissolved in water is absorbed by aquatic plants and enters the food
chain. Lead impairs metabolism and brings about congenital deformities, anaemia
etc.
3. Cadmium damages kidneys and liver.
4. Inorganic nitrates and phosphates promote growth of oxygen-consuming algae,
which result in the death of fishes and other aquatic animals.
5. Presence of dyes and compounds in the discharged water changes the colour of
water.
6. Soap, detergents and, alkalis result in foam formation.
7. Industrial effluents containing iron, free chlorine, phenol, manganese, oils,
hydrocarbons, ammonia, algae and microorganisms impair the taste and odours of
water.
8. The nitrates and phosphates dissolved in water accelerate the growth of
microorganisms, which consume much of the dissolved oxygen depriving fish and
other aquatic life (Eutrophication).
9. Biomagnifications is the increase of toxic materials at each tropic level of a food
chain.
For example, DDT after reaching a water system is absorbed by the microorganisms on
which smaller fishes feed. From them, DDT reaches the carnivorous animals. Since bigger
fishes consume more food, large amounts of DDT accumulates in their body.
CONTROL OF WATER POLLUTION
(i) Separate ponds and tanks to be used for cattle and animals.
(ii) Use of pesticides, insecticides and fertilizers should be done judiciously. Rapid
biodegradable substitutes for pesticides should be employed.
(iii) In towns where sewage facilities are not available, septic tanks should be made in
the houses.
(iv) Rivers and lakes should not be used for bathing or washing as it contaminates
water. .
(v) Domestic sewage and industrial wastes should be treated before discharging them
into drains.
Treatment of waste Water
Domestic sewage and industrial wastes should be properly treated before these are
drained in the mainstream water. Treatment involves the following two steps:
(i) Sewage treatment
It involves following steps:
Primary treatment. It involves physical processing of sedimentation, flotation and
filtration where sewage water is passed through screens to remove larger particles and then
through grinding mechanism to reduce the larger particles to smaller size. The sewage is
finally passed through settling tanks to remove suspended impurities.
Secondary treatment. Sewage obtained after primary treatment is sent to aeration tank
where it is mixed with air and sludge laden with bacteria and algae. The algae provide
oxygen to the bacteria and decompose organic matter into simple compounds. Chlorination
is finally done to remove bacteria.
Tertiary treatment. In the third and last step water is passed through ion exchangers
to remove dissolved salts.
(ii) Treatment of industrial effluents
Treatment of industrial effluents involves neutralization of acids and bases, removal of
toxic compounds, coagulation of colloidal impurities, precipitation of metallic compounds
and reducing the temperature of effluents to decrease thermal pollution.
SOIL POLLUTION
Soil Pollution
Like water and air, soil is also equally important for living organisms. It supports
plants on which. all other living organisms depend. The process of soil formation is so slow
that the soil may be regarded as a non-renewable source. Therefore, the study and control
of soil pollution is important. Any substance that reduces soil productivity is called soil
pollutant.
Sources of Soil Pollution
There are several materials, which adversely affect physical, chemical and biological
properties of the soil and thus reduce its productivity. These are
1. Chemicals present in industrial waste.
2. Pesticides and insecticides that are sprayed on crops. .
3. Fertilizers and manures that are added to the soil to increase the crop yield.
Effect of Soil Pollutants
Chemicals and pesticides affect the structure and fertility of soil by killing the soil
microorganisms. Pesticides are absorbed by the plants and then transferred to other organism.
Hence, they affected food chains and food webs. Excretory products of livestock and human
beings used as manure pollute the soil besides giving high yield. The faulty sanitation and
unhygienic practices of the people add to the soil pollution. Pathogens present in the wastes
and excreta contaminate the soil and vegetable crops causing diseases in man and
domesticated animals.
Types of Soil Pollution
It is of the following types-
(i) Positive soil pollution
Reduction in the productivity of soil due to the addition of undesirable substances like
pesticides, herbicides, fertilisers, etc. is called positive pollution. These pollutants have
cumulative effect and kill the soil organisms.
(ii) Negative soil pollution
It is caused by the removal 01 useful components from soil by erosion, deforestation and
improper methods of agriculture.
Salination of Soil
Increase in the concentration of soluble salts is called salination. This adversely affects
the quality and productivity of soil. It takes place in two ways: accumulation of salts dissolved
in irrigation water on the soil surface due to intensive farming and poor drainage, and
deposition of salts as white crust during summer months drawn by capillary action from the
lower surface to the top surface.
Control of Soil Pollution
Various measure to control soil pollution are-
1. Transfer stations for bulk shifting of refuse should be constructed in cities and big
towns.
2. Pneumatic pipes should be laid for collecting and disposing wastes.
3. Materials like paper, glass and plastics can be recycled.
4. Metals should be recovered from scrap and disposed materials.
5. Use of chemical fertilizers should be reduced by the use of bio fertilizers and
manures.
6. Use of pesticides can be reduced by adopting biological control of pests.
7. Use of cattle dung and agricultural wastes in biogas plants should be encouraged.
8. Deforestation can check soil erosion to a great extent.
Land Degradation
Besides pollution, land and soil face several other problems. Removal of topsoil is called
soil erosion. Soil erosion factors are water, wind, ocean, waves and glaciers, felling of trees,
overgrazing by cattle, over-cropping etc. Erosion occurs both in wet and dry regions. It leads
to floods.
Soil Erosion in India
Soil erosion is a worldwide phenomenon, but it is especially high in Central Africa,
China, India, Nepal, Australia, Spain, USA and USSR. India loses about 40,000 hectares of
land every year as an effect of wind and water erosion. Damage to the topsoil is 18.5% of
the total world’s loss. This is due to overgrazing by livestock. The population of livestock in
India is the highest in the world. Overgrazing damages the topsoil, which reduces soil
fertility.
(i) Deforestation of overgrazing
Over-grazing is the main cause of soil erosion in India. Roots of grasses act as binding
material and keep the soil intact, which upon grazing are destroyed.
(ii) Desertification
Loss of soil productivity by erosion of top soil results in the formation of deserts.
Deserts are spreading in all continents. Desertification takes place by shifting of sand dunes
by wind and .over-grazing. That desert in India is spreading at the rate of 12,000 hectares
of land every year.
(iii) Shifting cultivation
Tribal communities follow the practice of cutting down trees and setting them on fire
and then raising the crops on the resulting ash. This is called Jhuming in northeastern
India. It is harmful if the Jhuming cycles are longer than ten years but short cycles destroy
forests and cause soil erosion. e.g. Asia and Africa. .
(iv) Developmental activities
Large areas of fertile and productive croplands, woodlands and grasslands are lost to
various developmental activities such as rapid urbanization, building of airports, industries,
railways, roads, mining and construction of dams.
Control of Land Degradation
Following ways can control Land degradation
1. Restoration of forests and grass cover can help in prevention of soil erosion and
floods.
2. By replacing shifting cultivation with crop rotation, mixed cropping or plantation
cropping. Providing adequate drainage to irrigated and flood-prone lands can prevent
salinity.
3. Desertification can be controlled by spread of appropriate plant species and by
raising trees as wind breaks.
Noise Pollution
Noise can be defined as unwanted/unpleasant sound. So noise pollution is unwanted
sound dumped into the atmosphere without regard to the adverse effects it may have. In
our country urbanization and industrialization have become twin problems. Cities and towns
have sprouted up where industries are concentrated. Lack of town’ planning had led to
residential, commercial and industrial areas being mixed up. Houses, schools and hospitals
are situated near industries. All the boons of industrialization and civilization such as
motors, horns, heavy and light machinery, work and movement, blaring radios, supersonic
aeroplanes have become disturbing and irritant. Our ears can hear ordinary conversation
between 30-60 decibels. Modern conversation has a noise value of 60 decibels. A decibel
value greater than 80 decibels causes noise pollution. Noise becomes troublesome above 140
decibels..
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(i) Domestic sewage
This includes household’s wastes like food wastes, synthetic detergents used for washing
clothes and cleaning bathrooms and latrines and water based paints.
(ii) Industrial effluents
The industrial wastes are discharged in the adjoining rivers and streams through flush
lines of factories. The textiles, sugar and fertilizers factories, oil refineries, drugs manufacture,
rubber, and rayon fibers, the paper industries and the chemical factories all produce Chemical
pollution.
(iii) Agricultural source
Increased use of fertilizers has become essential for high yielding crop plants. Excess
of nitrates used as fertilizers seep into ground water is carried into lakes and pond. On
entering the drinking water supply system these create several health problems.
(iv) Pesticides
These include insecticides, fungicides, nematicides, rodenticides, herbicides and soil
fumigants. These contain chlorinated hydrocarbons, organophosphates, metallic salts,
carbonates, acetic acid derivatives etc. many pesticides are non-degradable. They pass through
the food chains and accumulate in fatty tissues thus causing several health hazards.
(v) Thermal pollution
Power plants and nuclear power stations are the main sources of thermal pollution of
water where water is used for cooling and becomes hot. The hot water on entering the main
water body raises its temperature, which kills fishes and other aquatic animals and increases
the rate of respiration in aquatic plants.
(vi) Pathogenic organisms
Sewage and domestic waste from houses introduces pathogenic organisms viz., protozoa,
worms-eggs and bacteria into water. This contaminated water if consumed causes jaundice,
typhoid, dysentery, cholera, tuberculosis etc.
(vii) Mineral oils
Oil from oil spills and washings of automobiles finds way into river water through
sewers.
(viii) Underground water pollution
Underground water particularly in cities and industrial areas is no more pure and safe.
The sources of underground water pollution are sewage, seepage, pits, industrial effluents,
septic tanks, fertilizers and pesticides, garbage etc.
(ix) Marine water pollution
River and stream network sources of water ultimately end up ocean and seas. Thus,
these acts as the sink of all natural and man-made water based pollutants. The main
sources of oceanic pollution are discharges of oil, greases, petroleum products, detergents,
sewage and garbage including radioactive wastes.
Effect of Water Pollutants
The main effects of water pollutants are:
1. Compounds of mercury, arsenic and lead are poisonous and chemically harmful as
they even affect water treatment plants e.g. organic sulphur compounds interfere
with nitrification.
2. Mercury when dissolved in water is absorbed by aquatic plants and enters the food
chain. Lead impairs metabolism and brings about congenital deformities, anaemia
etc.
3. Cadmium damages kidneys and liver.
4. Inorganic nitrates and phosphates promote growth of oxygen-consuming algae,
which result in the death of fishes and other aquatic animals.
5. Presence of dyes and compounds in the discharged water changes the colour of
water.
6. Soap, detergents and, alkalis result in foam formation.
7. Industrial effluents containing iron, free chlorine, phenol, manganese, oils,
hydrocarbons, ammonia, algae and microorganisms impair the taste and odours of
water.
8. The nitrates and phosphates dissolved in water accelerate the growth of
microorganisms, which consume much of the dissolved oxygen depriving fish and
other aquatic life (Eutrophication).
9. Biomagnifications is the increase of toxic materials at each tropic level of a food
chain.
For example, DDT after reaching a water system is absorbed by the microorganisms on
which smaller fishes feed. From them, DDT reaches the carnivorous animals. Since bigger
fishes consume more food, large amounts of DDT accumulates in their body.
CONTROL OF WATER POLLUTION
(i) Separate ponds and tanks to be used for cattle and animals.
(ii) Use of pesticides, insecticides and fertilizers should be done judiciously. Rapid
biodegradable substitutes for pesticides should be employed.
(iii) In towns where sewage facilities are not available, septic tanks should be made in
the houses.
(iv) Rivers and lakes should not be used for bathing or washing as it contaminates
water. .
(v) Domestic sewage and industrial wastes should be treated before discharging them
into drains.
Treatment of waste Water
Domestic sewage and industrial wastes should be properly treated before these are
drained in the mainstream water. Treatment involves the following two steps:
(i) Sewage treatment
It involves following steps:
Primary treatment. It involves physical processing of sedimentation, flotation and
filtration where sewage water is passed through screens to remove larger particles and then
through grinding mechanism to reduce the larger particles to smaller size. The sewage is
finally passed through settling tanks to remove suspended impurities.
Secondary treatment. Sewage obtained after primary treatment is sent to aeration tank
where it is mixed with air and sludge laden with bacteria and algae. The algae provide
oxygen to the bacteria and decompose organic matter into simple compounds. Chlorination
is finally done to remove bacteria.
Tertiary treatment. In the third and last step water is passed through ion exchangers
to remove dissolved salts.
(ii) Treatment of industrial effluents
Treatment of industrial effluents involves neutralization of acids and bases, removal of
toxic compounds, coagulation of colloidal impurities, precipitation of metallic compounds
and reducing the temperature of effluents to decrease thermal pollution.
SOIL POLLUTION
Soil Pollution
Like water and air, soil is also equally important for living organisms. It supports
plants on which. all other living organisms depend. The process of soil formation is so slow
that the soil may be regarded as a non-renewable source. Therefore, the study and control
of soil pollution is important. Any substance that reduces soil productivity is called soil
pollutant.
Sources of Soil Pollution
There are several materials, which adversely affect physical, chemical and biological
properties of the soil and thus reduce its productivity. These are
1. Chemicals present in industrial waste.
2. Pesticides and insecticides that are sprayed on crops. .
3. Fertilizers and manures that are added to the soil to increase the crop yield.
Effect of Soil Pollutants
Chemicals and pesticides affect the structure and fertility of soil by killing the soil
microorganisms. Pesticides are absorbed by the plants and then transferred to other organism.
Hence, they affected food chains and food webs. Excretory products of livestock and human
beings used as manure pollute the soil besides giving high yield. The faulty sanitation and
unhygienic practices of the people add to the soil pollution. Pathogens present in the wastes
and excreta contaminate the soil and vegetable crops causing diseases in man and
domesticated animals.
Types of Soil Pollution
It is of the following types-
(i) Positive soil pollution
Reduction in the productivity of soil due to the addition of undesirable substances like
pesticides, herbicides, fertilisers, etc. is called positive pollution. These pollutants have
cumulative effect and kill the soil organisms.
(ii) Negative soil pollution
It is caused by the removal 01 useful components from soil by erosion, deforestation and
improper methods of agriculture.
Salination of Soil
Increase in the concentration of soluble salts is called salination. This adversely affects
the quality and productivity of soil. It takes place in two ways: accumulation of salts dissolved
in irrigation water on the soil surface due to intensive farming and poor drainage, and
deposition of salts as white crust during summer months drawn by capillary action from the
lower surface to the top surface.
Control of Soil Pollution
Various measure to control soil pollution are-
1. Transfer stations for bulk shifting of refuse should be constructed in cities and big
towns.
2. Pneumatic pipes should be laid for collecting and disposing wastes.
3. Materials like paper, glass and plastics can be recycled.
4. Metals should be recovered from scrap and disposed materials.
5. Use of chemical fertilizers should be reduced by the use of bio fertilizers and
manures.
6. Use of pesticides can be reduced by adopting biological control of pests.
7. Use of cattle dung and agricultural wastes in biogas plants should be encouraged.
8. Deforestation can check soil erosion to a great extent.
Land Degradation
Besides pollution, land and soil face several other problems. Removal of topsoil is called
soil erosion. Soil erosion factors are water, wind, ocean, waves and glaciers, felling of trees,
overgrazing by cattle, over-cropping etc. Erosion occurs both in wet and dry regions. It leads
to floods.
Soil Erosion in India
Soil erosion is a worldwide phenomenon, but it is especially high in Central Africa,
China, India, Nepal, Australia, Spain, USA and USSR. India loses about 40,000 hectares of
land every year as an effect of wind and water erosion. Damage to the topsoil is 18.5% of
the total world’s loss. This is due to overgrazing by livestock. The population of livestock in
India is the highest in the world. Overgrazing damages the topsoil, which reduces soil
fertility.
(i) Deforestation of overgrazing
Over-grazing is the main cause of soil erosion in India. Roots of grasses act as binding
material and keep the soil intact, which upon grazing are destroyed.
(ii) Desertification
Loss of soil productivity by erosion of top soil results in the formation of deserts.
Deserts are spreading in all continents. Desertification takes place by shifting of sand dunes
by wind and .over-grazing. That desert in India is spreading at the rate of 12,000 hectares
of land every year.
(iii) Shifting cultivation
Tribal communities follow the practice of cutting down trees and setting them on fire
and then raising the crops on the resulting ash. This is called Jhuming in northeastern
India. It is harmful if the Jhuming cycles are longer than ten years but short cycles destroy
forests and cause soil erosion. e.g. Asia and Africa. .
(iv) Developmental activities
Large areas of fertile and productive croplands, woodlands and grasslands are lost to
various developmental activities such as rapid urbanization, building of airports, industries,
railways, roads, mining and construction of dams.
Control of Land Degradation
Following ways can control Land degradation
1. Restoration of forests and grass cover can help in prevention of soil erosion and
floods.
2. By replacing shifting cultivation with crop rotation, mixed cropping or plantation
cropping. Providing adequate drainage to irrigated and flood-prone lands can prevent
salinity.
3. Desertification can be controlled by spread of appropriate plant species and by
raising trees as wind breaks.
Noise Pollution
Noise can be defined as unwanted/unpleasant sound. So noise pollution is unwanted
sound dumped into the atmosphere without regard to the adverse effects it may have. In
our country urbanization and industrialization have become twin problems. Cities and towns
have sprouted up where industries are concentrated. Lack of town’ planning had led to
residential, commercial and industrial areas being mixed up. Houses, schools and hospitals
are situated near industries. All the boons of industrialization and civilization such as
motors, horns, heavy and light machinery, work and movement, blaring radios, supersonic
aeroplanes have become disturbing and irritant. Our ears can hear ordinary conversation
between 30-60 decibels. Modern conversation has a noise value of 60 decibels. A decibel
value greater than 80 decibels causes noise pollution. Noise becomes troublesome above 140
decibels..
<<< Previous Next >>>
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