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MODULE - 1
Environmental Science Senior Secondary Course
Environment through
Ages
Notes 3
DEGRADATION OF NATURAL
ENVIRONMENT
When humans evolved more than two millions years ago, the natural resources were over
abundant as compared to human needs. As human population increased, more and more
food and resources for shelter were required and these were drawn at an increasing rate
from the environment. Even today, natural resources are being exploited by humans to
meet their needs. In this lesson you shall learn how human activities degrade and deplete
the natural resources of the environment.
OBJECTIVES
After completing this lesson, you will be able to:
· recall the concept of environmental degradation and factors that cause it;
· explain how exploitation of natural resources leads to environmental degradation;
· explain the relationship between population growth and environmental
degradation;
· explain the relationship between urbanization and deterioration in environment;
· explain the causes and effects of deforestation;
· draw a relationship between excessive mining and environmental degradation;
· explain the meaning of fossil fuels and the impact of their use on the environment;
· discuss how modernization of agriculture has adversely affected the environment;
· discuss the impact of industrialization on abiotic (air, water and soil) and biotic
resources (plants and animals) of the environment;
· list local, regional and global backlashes caused by environmental degradation;
· describe the impact of environmental degradation on life.
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Degradation of Natural Environment MODULE - 1
Environment through
Ages
3.1 CONCEPT OF ENVIRONMENTAL DEGRADATION
Increasing use of natural resources by rapidly increasing human population has resulted in
overexploitation of natural resources. The consequences of such exploitation are clearly
seen in soil erosion, loss of biodiversity and pollution of land, air and water bodies. The Notes
degradation of the environment from overexploitation has reached a level which is threatening
human well-being and survival.
3.2 RECKLESS EXPLOITATION OF NATURAL RESOURCES
LEADS TO ENVIRONMENTAL DEGRADATION
In nature, there exists an ecological balance. The activities of various organisms are
balanced. The interaction between abiotic and biotic components are so fine tuned that
there exists an equilibrium in nature.
As years passed by, human activities interfered with this equilibrium. Uncontrolled human
activities caused damage to the environment.
Some of the human activities that have led to environmental degradation are mentioned
below-
1. Forests are natural resources but they have been cut down for use by humans for
converting them into the cultivable fields, for building houses and for taking away logs
for making shelters and furniture or fuel. The rate at which trees are cut far exceeds the
rate at which trees grow, so forests are getting denuded.
2. Trees lose lot of water through transpiration. This helps in forming rain clouds. Cutting
of trees and clearing of forest reduced rainfall in the area. Also removal of plants and
trees leads to soil erosion.
3. Forests are natural habitats of wild life. Extinction of wild life species is on the rise
because their natural habitats are being destroyed due to deforestation.
4. Non-renewable energy resources such as coal, natural gas and petroleum are being
used up speedily, leading to their depletion.
These are examples show the loss of natural resources due to the overuse by humans.
On the other hand,
1. Excessive burning of coal, wood, kerosene, petrol etc. release toxic gases such as
SO (sulphur dioxide), NOx (oxide of nitrogen),CO(carbon monoxide) and
2
hydrocarbons in the air. These gases are also emitted by industries, power plants,
automobiles and aircrafts. The toxic gases pollute air which adversely effects human
health and plants.
2. Acid water from mines, toxic waste of industries, chemical fertilizers and pesticides
from agricultural fields have polluted rivers and other water bodies.
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MODULE - 1
Environmental Science Senior Secondary Course
Environment through
Ages
3. The problem of soil pollution is increasing day by day in villages, cities and industrial
areas due to faulty disposal of solid and liquid wastes generated from households and
industries.
Thus humans have spoilt the environment by (i) depleting natural resources to a critical
Notes level and (ii) causing pollution to natural water bodies and land areas.
3.3 IMPACT OF POPULATION GROWTH ON ENVIRONMENT
The enormous increase in human population is making the future of humans insecure. It is
estimated that 5 million people lived in the world at the time when agriculture begin about
12000 years ago. The population of our country alone is now well over one billion.
3.3.1 Factors leading to rise in population
Many factors have contributed to the enormous rise in human population. These are listed
below:
1. Improved agricultural practices have helped in increasing food production, hence food
became available.
2. Progress in medicine prevented deaths due to injury and epidemic diseases.
3. Average longevity of humans has increased since heart, lung and kidney disorders as
well as other diseases can now be diagnosed and treated through modern medical
technology.
3.3.2 Impact of population growth on environment
With growing population, requirement for space, shelter, and commodities have exerted
enormous pressure on the environment. To provide for these, land use has change
dramatically. It has already been seen that forests have been cleared for cultivation of grain
and fruit crops.
1. Clearing land for cultivation to grow more food
Forests and natural grasslands have been converted to farmlands. Wetlands have been
drained and arid lands have been irrigated. These changes have been made to grow more
food and more raw materials. But in doing so, the natural resources have been depleted
and the landscapes have undergone drastic changes. For example, forests have been
cleaned over large for cultivation of agriculture crops. Many mangrove forests known to
reduce erosion and stabilize shorelines have been cleared use for growing food crops to
meet the needs of the growing population.
2. Water scarcity
Water received as rainfall, flows into rivers, lakes and other water bodies. Some of it
seeps into the ground and reaches the ground water. At certain depth of the soil, all the
pore spaces between soil particles are saturated with water. This depth is called Water
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Degradation of Natural Environment MODULE - 1
Environment through
Table. The water table may remain stable if the drawn from the ground water is replenished Ages
by the seepage of the rain water. But if water withdrawal exceeds beyond the rate of
replenishment of the ground water table keep on receding and resulting in drying out of
wells. In many areas excessive withdrawl has depleted ground water resources causing
acute water scarcity. Notes
3. Need for human settlements
Apart from excessive land use changes for growing food, large population means greater
requirement for shelter. To make houses for so many, stones and other building materials
have to be quarried more rocks have to be blown off and more water to be used.
4. Need for transport
Elaborate network of transport is required to fulfill the growing need of teeming millions.
Various modes of transports have been developed which consume growing quantities of
fossil fuels such as coal, gas and petroleum, polluting the atmosphere.
5. Need for various commodities
Articles of everyday use such as plastic vessels, mugs, buckets etc., agricultural implements,
machinery, chemicals, cosmetics etc are manufactured in factories. The raw materials and
fossil fuels and water needed to run industries for manufacturing these products lead to
their depletion. Rapid industrialization has also led to pollution from dumping of industrial
effluents into rivers and other water bodies. Rapid industrialization has caused much damage
to the environment. Mining activities have depleted stock of mineral resources particularly
fossil fuels.
Present day industrial civilization is becoming a burden on nature and it is time for us to
learn to live in harmony with nature.
6. Slum development
Over populated areas result in congested roads and slum formation which lack basic
amenities like drinking water, drainage, waste disposal, lack of hygienic conditions and
filthy environment create potential conditions for public health problems including spread
of epidemic diseases. Discharge of untreated effluents and throwing of waste into water
bodies have polluted most of the lakes and rivers.
7. Pollution resulting from overpopulation
Holy rivers Ganga, Yamuna and other are suffering from pollution due to discharge of
effluents from industries, human settlements, bathing, washing of clothes and throwing of
garbage into the river.
INTEXT QUESTIONS 3.1
1. State any two types of environmental degradation caused by humans.
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