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Chapter 16
Environmental issues
Pollution is any undesirable change in physical, chemical or biological characteristics of air, land, water or soil
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In order to control environmental pollution, the
Government of India has passed the Environment (Protection) Act, 1986 to protect and improve the quality of our
environment
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They are mentioned below in fig
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Fig
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Sources of pollution
Air pollution and its control
Air pollution is harmful for both plants and animals
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They affect the
respiratory system of the humans
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These pollutants are very harmful, they should be filtered out before it should be released into the
environment
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Particulate matter if inhaled causes breathing and respiratory symptoms, inflammations, irritations, and premature
deaths
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To prevent the emission of poisonous gases
from automobiles, catalytic converters, having expensive metals namely platinum-palladium and rhodium as the catalysts
are fitted into automobiles
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The Air (Prevention and Control
of Pollution) Act came into force in 1981 in India
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Controlling Vehicular Air Pollution: A Case Study of Delhi
Delhi leads the country in its level of air pollution
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The supreme court had advised the public vehicles to switch from diesel to

compressed natural gas (CNG)
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Other
methods were also used to reduce pollution in Delhi such as use of unleaded petrol, phasing out of old vehicles, use of
low Sulphur petrol etc
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Domestic sewage and industrial effluents
0
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Solids are easy to remove, but dissolved salts such
as nitrates, phosphates and other nutrients are difficult to remove
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Biological oxygen demand can be used to measure
amount of biodegradable organic matter in sewage water
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Fig
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Water pollution

Biomagnification refers to the increase in concentration of toxicant at successive trophic levels
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Biomagnification of DDT
Eutrophication is defined as ageing of the lakes due to nutrient enrichment
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Nutrients are
introduced into the lake from different sources like surface run-off, streams, etc
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Over the course of time the lake becomes shallower due to the deposition of
silt and organic debris
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Slowly the lake is populated by floating
plants and eventually the lake is converted to land
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Pollutants from human activities like industrial and domestic effluents can radically accelerate the aging process
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The pollutants like nitrates and phosphates
promote rapid growth of algae
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Thus,
due to increased water pollution a lake can choke to death
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For example, pipe or ditch
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For example, nutrient run-off from the agriculture land

Effects of water pollution
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Death of aquatic animals due to depletion of oxygen
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Contaminated water causes various diseases
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Approximately 80 per cent of diseases associated with stomach
in India are caused by polluted water
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It involves•

Conventional sedimentation followed by filtering and chlorine treatment
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Appropriate plants, algae, fungi and bacteria were seeded into this area
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Hence the water gets purified naturally as it flows through the marshes
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Dumping of these wastes give
birth to flies and rats
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Waste is categorized as
biodegradable, non-biodegradable and recyclable
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Non-biodegradable wastes cannot be naturally broken down
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Recyclable wastes are substances that can be used to retrieve at least few useful substances
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Hospital wastes are hazardous
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Electronic waste must be recycled to obtain useful metals
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This
increases the risk of exposure of the workers towards the toxic substances
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He
developed Polyblend
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It can be mixed with bitumen and used
for laying roads
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Agrochemicals and their effects
Use of fertilizers and pesticides has increased manifold for crop production
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They cause soil, water and air pollution
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In this waste products
from one process are cycled in as nutrients for other processes
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Crop waste can also be used as natural fertilizer in the form of compost
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It affects both plants and animals as it causes mutations
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Therefore, nuclear waste is an extremely potent pollutant and has to be dealt with utmost caution
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The earth atmosphere traps the sun rays which increases
the temperature of the earth
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Carbon-dioxide, methane, nitrous acid, water vapor
acts as greenhouse gases
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This is known as global warming
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Ozone depletion in the stratosphere
Ozone is present in the stratosphere which protects the atmosphere from the harmful ultraviolet radiations
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They are harmful for DNA and proteins present in the living organisms
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Oxygen when absorbs ultraviolet rays, it breaks into oxygen atoms
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The major cause of ozone depletion is a group of chemicals called as chlorofluorocarbon (CFCs) such as Freon
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These CFCs in atmosphere absorbs ultraviolet rays and forms chlorine free radical
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5
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Degradation of ozone causes ozone
hole
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UV-B rays are
dangerous and damages living organisms
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Recognizing the
deleterious effects of ozone depletion, an international treaty, known as the Montreal Protocol, was signed at Montreal
(Canada) in 1987 (effective in 1989) to control the emission of ozone depleting substances
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Soil erosion takes place due to human activities
like over-grazing, over-cultivation, deforestation and poor irrigation practices
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This will eventually lead to desertification
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Water logging and soil salinity: Improper drainage of water leads to water logging of the soil
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These salts are then deposited on the soil surface as a thin crust
or collected around the plant roots
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Green revolution
has played a major role in increased water logging and soil salinity
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It is the result of
human activities
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Conversion of forests to farmlands: Forests are cleared by cutting of trees and burning of stumps
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After cultivation of crops the land is left fallow to allow the soil
nutrients to regenerate
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Reforestation: It is the process of restoring forest cover to a place where forests once existed but were cleared off
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The process can be sped up by human intervention involving planting plants and
trees
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In 1731, a forest nearby their village
was ordered to be cleared by the King of Jodhpur
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In her honor, the Government of India instituted an award called as “Amrita Devi Bishnoi Wildlife
Protection Award”
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Chipko Movement: Local women of Garhwal region in 1974 protected the trees against felling by hugging them
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It aims towards the involvement of local
communities and people in sustainable development of forests

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