Important Notes - 10th Science - Striving for Better Environment by Ednexa

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Striving For Better Environment Part – I
Pollution
Pollution is contamination of natural environment that can harmfully affect the
ecosystem.
Pollutants
Pollutants are the products which affect the normal functioning of ecosystem and have
an adverse effect on plants, animals, and humans. For eg._
∙
Carbon dioxide in air is useful for photosynthesis in plants but when it exceeds
certain limit of concentration it becomes a pollutant.
∙
Loud music sometimes increases heartbeats, heart palpitation and headaches,
dilation of pupils, etc.
Types of pollution:
Pollution takes place in three parts of environment that is air, water and soil. Thus there
are 5 types of pollution.
∙
Air Pollution.
∙
Water Pollution.
∙
Soil or Land Pollution
∙
Noise Pollution.
∙
Radioactive Pollution.
Air Pollution
Modernization, industrialization has led to increase in air pollution. The major sources of
air pollution are transportation engines, power and heat generators, industrial process
and burning of soil waste.
In rural areas burning of firewood, cowdung cake, agricultural residue, etc. cause air
pollution. The earth itself contributes to air pollution through volcanic eruption, wildfire,
sand and dust storms and other natural processes.
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Air Pollutants
Air pollutants are classified as follows:
1.
According to origin:
a.
Primary Pollutants:
The pollutants that are emitted directly from the sources and are found in
the atmosphere in the form in which they were emitted are known as primary
pollutants. E.g. Ash, smoke, dust, radioactive compounds, oxides of sulphur,
carbon, nitrogen are primary pollutants.
b.
Secondary Pollutants:
The pollutants that are formed in the atmosphere by chemical reactions
between primary pollutants and atmospheric constituents are known as
secondary pollutants. e.g. SO3, O3, Hydrogen cyanide, peroxyacetyl nitrate,
ketones, etc. are secondary pollutants.
2.
According to state of matter:
a.
Gaseous Air Pollutants:
These pollutants exist in gaseous state at normal temperature and pressure.
e.g: CO, CO2 and oxides of sulphur and nitrogen.
b.
Particulate Air Pollutants:
These are non-gaseous substances. e.g. suspended droplets, solid particles
and mixture of both.
3.
According to sources:
a.
Natural Sources:
These include volcanic eruption, sand and dust storm, forest fires etc.
b.
Man made Sources:
These include human activities such as industries, factories, aircrafts,
nuclear experiments, automobiles, agriculture and power plants.
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Sources of Air Pollution:
1.
Air Pollution Due To Transportation:
Vehicles are major contributors to air pollution. More than 50% of total air
pollution is caused by vehicles.
2.
Air Pollution Due to Industry:
Industries such as chemical, petrochemical, thermal power plants, foundries,
cotton mills, paper mills cause most air pollution. The smoke coming out from the
factories has small particles of dust, carbon, metals and other solids, liquids and
radioactive materials from various sources which get mixed in smoke and pollute
the air. SO2 is produced in various industrial processes. SO2 combines with oxygen
and water to form sulphuric acid in the atmosphere. This acidic solution in
atmosphere results in acid rains.
3.
Air Pollution Due to Agriculture
Open field burning is the main contributor to air pollution due to agriculture.
Burning of rice straw emits gases like SO2, CH4, CO, Oxides of nitrogen and large
amount of particulates. Pesticides used in agriculture sector emit many toxic
chemicals. Industrial farms pollute air by emitting foul odour, air borne particles.
Manure decomposition produces green house gases.
4.
Air Pollution Due To various Types of Burning.
Burning of coal, forest fires and fire crackers, municipal waste also contribute to air
pollution.
Fig. Fire Crackers
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Effect of air pollution
Air pollution is responsible for major health effects. The health of countless people
is endangered by air pollution every year.
Air pollutants affect human body depending on following factors.
1.
Concentration of air pollutants.
2.
Nature of the pollutants.
3.
Time period of exposure.
Effect on Human Beings
Air pollution can affect our health in many ways with both short term and long
term effects.
Short term effects includes
∙
Irritation of eyes, nose, mouth and throat
∙
Respiratory infections such as bronchitis, pneumonia
∙
Headaches, nausea and allergy
∙
Asthma attacks
∙
Reduce lung functioning
Long term effects include
∙
Chronic pulmonary disease.
∙
Cardio vascular disease
∙
Lung cancer
∙
Premature death.
Effects on animals
Air pollution also affects the breathing of animals. Acid rain creates serious
problems for wide life
Effect on plants
∙
Reduction in growth of various parts of plant
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Yellowing or chlorosis of the leaf.
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Effect on Environment
Air pollution can cause a variety of environmental effects. The increase in CO2
levels due to deforestation and fuel combustion, increase the atmospheric
temperature of the earth. This results in the melting of glaciers and polar ice. If the
pattern of rainfall changes, it will affect agricultural production.
Acid Rain
Acid rain is rain water containing harmful amounts of nitric and sulphuric acids.
When fossil fuels such as coal, wood, petroleum are burnt, nitrogen oxides and
sulphur oxides are released into the atmosphere. These oxides are soluble in
water. During rain, these oxides react with large quantities of water vapours of
atmosphere to form acids like sulphurous acid, sulphuric acid, nitric acid and
nitrous acid. These acids mix with mist, rain water drops or snow and change its
composition. The rain or snow that falls to the ground is Acid Rain.
Fig. Acid Rain
Effect of Acid Rain
∙
Acid rain increases acidity in the soil and water bodies which damages trees,
and make water unsuitable for fish and wildlife.
∙
It corrodes buildings, status, sculptures, bridges, monuments, and fences,
etc. that are part of our national assets.
∙
It adversely affects agriculture and crop lands.
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Ozone layer depletion
Stratosphere, the second layer of the atmosphere reaches 48 km above of the earth
surface, and at the very top it contains ozone. Ozone layer absorbs the harmful UV
rays from the sun and protects both plant and animal life on the planet.
Ozone layer depletion
Causes of ozone depletion
Scientific evidence reveals that stratospheric ozone is being destroyed mainly by
chlorine atoms of chloroflurocarbon (CFC) molecules. CFC’s were used as coolants
in refrigerators, freezers and air conditioners in buildings and cars manufactured
before 1995. It is also found in industrial solvents, dry cleaning agents and
hospital sterilants, aerosols and foam.
Once these CFC molecules are broken apart by UV light, it releases chlorine and
bromine which further demolish ozone at an alarming rate.
A hole has been observed in the ozone layer in the stratosphere near Antarctica.
This hole allows the ultraviolet rays of the Sun to reach the earth directly. These UV
rays cause skin cancer, cataract in human beings. Ozone depletion can affect
animals and plants as well.
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Green house effect
Green house effect is a phenomenon. The impact of green house effect is Global
warming and climate change.
Our earth receives energy from the Sun. The earth surface absorbs the solar energy
and releases it back to the atmosphere as infrared radiation, some of which goes
right back into space.
But some of the infrared radiation emitted by the earth is absorbed by CO2, CH4
water vapours in the atmosphere and sent back towards the earth surface as heat
energy causing a warming known as Green House effect.
The gases that contribute to the green house effect are called as green house
gases. The warming due to greenhouse gases is expected to increase as humans
add more green house gases to the atmosphere leading to global warming.
Water Pollution
When toxic substances enter lakes, streams, rivers, oceans and other water bodies, they
get dissolved or lie suspended in water or get deposited on the bed. This results in the
pollution of water whereby the quality of water deteriorates, affecting aquatic ecosystem.
Water Pollutants
There are three types of water pollutants.
1.
Biological
2.
Inorganic
3.
Organic
1.
Biological Water Pollutants
Algae, Bacteria, Virus and Parasites are major biological impurities that make water
harmful for human consumption. These biological impurities cause many diseases.
2.
Inorganic Water Pollutants
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Water contains some suspended particles which may consist of fine sand, clay, soil
and precipitated salts and some dissolved particles such as rock and other
compounds from the earth. Toxic metals like Arsenic, Cadmium, lead, Mercury,
Silver are the most harmful pollutants. Traces of radioactive elements are found in
water bodies.
3.
Organic Water Pollutants
Wastes from industries are the major organic pollutants.
Sources of Water Pollution:
Water pollution is caused by several sources, both natural and man-made.
Natural Sources:
Due to heavy rains, minerals from land get washed into river and then oceans. This leads
to uncontrolled growth of water weeds. Similarly dead animals, animal waste, ashes and
chemicals released due to forest fires, sulphur compounds released after an earthquake
get washed into water sources due to rain.
Man Made Sources:
Manmade sources such as city sewage and industrial waste are the major source of water
pollution. These are classified into:
1.
Domestic sewage
2.
Industrial wastes
3.
Radioactive wastes
4.
Agricultural runoff
5.
Oil spills
6.
Thermal pollution
1.
Domestic Sewage:
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Waste water originating from kitchen, bathrooms, toilet is domestic sewage.
2.
Industrial Waste:
Waste materials like acids, alkalis, toxic metals, oil, grease, dyes, pesticides and
even radioactive material are poured in to the water bodies by many industrial
units. The construction Industry discharges slurries such as gypsum, cements,
abrasive, metals and poisonous solvents.
3.
Radioactive Waste:
Radioactive wastes are produced from industrial, medical, atomic power plants and
scientific processes that use radioactive materials.
4.
Agricultural Runoffs:
The use of land for agricultural and the practices followed in cultivation greatly
affect the quality of ground water.
5.
Oil Spills:
Accidental release of oil into a body of water as from a tanker, off shore drilling rig
or underwater pipeline and wells often present a hazard to marine life and the
environment.
6.
Thermal Pollution:
The thermal power plants and other industries located near the rivers and sea use
water for cooling purposes. They release the recycled hot water into the water
bodies leading to thermal pollution. This hot water increases the temperature of
aquatic environment.
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Effect of Water Pollution:
1.
Effects on human beings:
Polluted drinking water contains pathogenic and non – pathogenic organisms. The
several water borne diseases like cholera, typhoid, diarrhoea, dysentery, hepatitis,
polio and jaundice can be caused by the polluted water.
2.
Effects on Aquatic life:
Any physical or chemical change in aquatic systems due to pollutants brings
changes in individual organisms.
Eutrophication or Nutritional Enrichments
The enrichment of water bodies by inorganic plant nutrients like nitrate, phosphate
occurring either naturally or due to human activity is Eutrophicaton. The process of
eutrophication takes place due to introduction of nutrients and chemicals through
discharge of domestic sewage, industrial effluents and fertilizers from agricultural fields.
Fig. Eutrophication
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Soil Pollution
Soil Pollution is mainly the result of penetration of harmful pesticides, insecticides and
other chemicals.
Fig. Soil Pollution
Types of Soil Pollutants
The different types of soil pollutants are,
∙
Pesticides
∙
Inorganic pollutants (e.g. Hg, As, Ni, Cd, Pb etc)
∙
Radioactive Elements
∙
Organic wastes (detergents, borates, agricultural wastes, crop residues, sewage
effluents)
∙
Air borne contaminants like gaseous emissions from industrial areas burning fuels,
smelting and mining.
Sources of soil pollution:
1.
Industrial Wastes:
This waste is generated by industrial during manufacturing processes such as
chemicals, paints, paper and pulp mills and foundry wastes. Thermal power plants
generate a large quantity of fly ash. These wastes are sometimes dumped directly
into the soil.
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Domestic Waste:
Domestic wastes includes garbage, domestic refuse and discarded solid materials.
3.
Chemical Fertilizers:
The excessive use of chemical fertilizers creates pollution.
4.
Biomedical Wastes:
These include out dated medicines, cytotoxic drugs, soiled dressing body organs
and tissues, disposable syringes, intravenous fluid bottles, gloves, needles, blades.
5.
Pesticides:
Effect of Soil Pollution:
a.
Sewage sludge contains many pathogenic bacteria, viruses and intestinal
worms which cause various types of diseases.
b.
Human and animal excreta contains pathogens that contaminate soil and
vegetable crops when used as manure. This leads to various diseases related
to digestive system.
c.
Land and soil pollution is responsible for loss of fertility and productivity of
soil.
d.
Soil pollution can lead to water pollution if toxic chemicals leach into ground
water or contaminated run off reaches streams or lakes.
e.
Radioactive material and soil contaminants move away from the soil into
crops, live stock and human bodies through food chains.
Noise Pollution:
Like other pollutants, noise is also a by-product of industrialization, urbanization and
modern civilization, Sources of noise pollution:
1.
Industrial:
Include noise from various industries and big machines working at a very high
speed and very high noise intensity.
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Non-industrial:
Includes noise created by transport or vehicular traffic and neighbourhood noise
generated by various house hold appliances
The leading sources of nose pollution are:
1.
Road traffic noise
2.
Air craft noise
3.
Rail roads
4.
Construction noise
5.
Noise in industries
Effects of Noise Pollution:
Effects of the noise pollution on human beings depend on noise intensity,
frequency and exposure duration.
There are three types of effects on man,
1.
Auditory effects:
Auditory fatigue, deafness
2.
Non-auditory effects:
Communication interference, sleep interference, concentration interference,
ill temper, annoyance, violent behavior, mental disorientation, bickering and
loss of working efficiency.
3.
Physiological effects:
Nausea, fatigue, anxiety, visual disturbances, insomnia, hypertension, cardio
vascular disease.
Radioactive Pollution:
Due to human activity, high energy radioactive particles mix in air, water, and soil and
pollute it. This is known as radioactive pollution.
The sources for radioactive pollution are as follows:
∙
Nuclear power plants and nuclear fuel
∙
Nuclear weapons
∙
Mining
∙
Nuclear accidents
∙
Medical waste
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Effects of Radioactive pollution:
Radioactive pollution has destructive effects on the entire ecosystem.
Polluted soil transfers radioactive substances to plants growing on it. This can
affect plant DNA. Some plants die and others may develop weak seeds.
Effect of radiations on human being is mild to severe depending upon the level and
duration of exposure. When the human body is exposed to radiation, it reacts with
biological molecules forming ions. These ions destroy cells, protein enzymes,
nucleic acid.
Damage caused by radiations may be transmitted to many generations.
Abatement of Pollution:
We take corrective actions to reduce the amount or intensity of the pollutions.
The Government of India has laid down laws and guidelines for prevention, control and
abatement of pollution. Some of the laws related to pollution control are:
1.
Water (prevention and Control of Pollution) Act, 1974
2.
Air (Prevention and Control of Pollution) Act, 1981
3.
Environment (Protection) Act, 1986
Various Laws and Rules have been made for hazardous waste, biomedical waste,
solid waste, prevention of Noise Pollution, etc.
The Central Pollution Control Board (CPCB) and Maharashtra Pollution Control
Board (MPCB) are the government bodies who confirm these laws being followed by
all the organizations like factories, industrial estates, municipalities, Zilla
Parishads, Panchayat samities and Grampanchayats.
In order to control air pollution from industry, following methods are adopted:
1.
Dilution of source discharge by tall chimneys.
2.
Source correction methods like changing raw material equipment
modification, process modification.
3.
Using effective pollution controlling equipments like dust collectors,
electrostatic precipitators, wet scrubbers, etc.
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Role of Citizens in Pollution Control:
The concern about abatement of pollution is growing. Each one of us can
contribute individually or through collective efforts to reduce pollution.
1.
Plant trees and develop gardens, parks and open grounds in the locality.
2.
Save fossil fuels and reduce pollution, minimize electricity consumption.
3.
Use public transport instead of private vehicles.
4.
Use nonconventional source of energy like solar, wind energy, tidal energy
5.
Maintain vehicles in well tuned conditions.
6.
Keep your home and public places clean. Keep our own locality free from
pollution.
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