Science and Environment 8

on the verge of extinction. Therefore, we should conserve the forest to protect the
habitat of wild animals.

b. Need and Importance

Wild animals and birds have a great importance. They play an important role to
maintain a balance in the ecosystem. They are the parts of the ecological system. They
contribute in economic development of a nation. It is so because many people visit
forests or protected areas to observe the beauty of animals and birds. People conduct
research and study them. The scientific findings can be utilized for the welfare of
human beings as well as other living beings. Wild animals and birds provide raw
materials for industries. It is found that there is cross-fertilization between domestic
animals and wild animals. It helps to improve breeds of animals.

22.8 Rare Animals and Birds in Nepal

Rare animals are the animals which are found few in number in a place and time. The
animals which are found in Nepal only are rare for the rest of the world. Similarly, the
animals which are found few in number in Nepal and in plenty in other parts of the world
are rare for Nepal. In Nepal, there are many species of rare plants and animals. Some of
them are discussed below:

a. One-Horned Rhinoceros

Scientific Name: Rhinoceros unicornis

Body Structure: One-horned rhinoceros is Fig. 22.3 Rhinoceros unicornis
one of the protected animals of Nepal. Its
length is about 3.8m and the height ranges
from 1.1 to 1.7 m. Its weight varies from
2000 to 4000 kg. Its body is covered with
thick skin which acts as an armour. There
is no hair on its body except in the tail
tip and ear fringes. It has brown or grey
body colour. There is a horn on its nose. It
produces one baby at a time.

Habitat: One-horned rhinoceros is found in Terai region of Nepal. It lives in swampy
grassland and sal forests of Chitawan and Bardiya National Parks. One-horned
rhinoceros is classified by the IUCN Red list of threatened species as 'endagered'. In
Nepal, Rhino is poached for its horn, hide and hoof.

Food: It feeds on grass, shrubs, foliage and aquatic plants.

life span: Its life span is about 40 – 50 years.

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 345

b. Royal Bengal Tiger

Scientific Name: Panthera tigris

Body Structure: It has black strips on its

yellow to light orange coat. It is about

2.7 m to 3.1 m in length and 1 m in height. Its

weight varies from 130 to 200 kg. It produces

up to 4 babies at a time. Fig. 22.4 Royal Bengal Tiger

Habitat: It is found in the forest of Terai

region. It is found in Chitwan National Park, Bardiya National Park, Parsa Wildlife

Reserve and Shukla Phanta Wildlife Reserve. It is also an endangered species.

Food: It feeds on vertebrates like Chittal, Wild pig, Deer, Ratuwa, Laguna, etc.

life span: Its life span is about 15 years.

c. Asiatic Rock Python

Scientific Name: Python molurus Fig. 22.5 Asiatic rock python

Body Structure: It is a large snake. Its body is
white, black and spotted. Its body is about 7
m long and weight is about 90 kg. It is a non-
poisonous snake. It has a series of dark brown
and circular spots. It has a wide head and small
eyes.

Habitat: It is found in dense forest of Terai region. It hides itself in a log of wood and
dry leaves.

Food: It feeds on small mammals, birds and reptiles. It is also an endangered species.

life span: Its life span is about 19 years.

d. Asiatic Elephant Fig. 22.6 Asiatic elephant

Scientific Name: Elephus maximus

Body structure: Elephant is the largest land
animal. Its height is about 3.5 m. It has a
long trunk and two tusks. The tusks of male
elephant are larger than that of the female. It
produces one baby at a time.

Habitat: It is found in dense forest of Terai
region. It is found from Jhapa to Kanchanpur.
It is also an endangered mammal. It is hunted

muzzle / ˈ m ʌ z l / - the nose and mouth of an animal

346 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

for its tusks.
Food: It feeds on twigs, leaves, grasses, bamboo shoot and grain.
life span: Its life span is about 70 years.

e. Red Panda

Scientific Name: Ailurus fulgens

Body Structure: Red panda is an attractive wild
animal which is slightly larger than cat. It has a
rounded head, pointed large ears and stumpy
muzzle. It has rusty red body colour.

Habitat: It is found in the temperate forest Fig. 22.7 Red panda
at an altitude of about 3000 m. It is generally
found in Kanchenjunga and Taplejung. It is
an endangered mammal. It is hunted for its
attractive furry skin.

Food: Its main food is bamboo shoot, grasses, fruits, etc.

life span: Its life span is about 7 years.

f. Giant Pied Hornbill Fig. 22.8 Giant pied hornbill

Scientific Name: Buceros bicornis

Body Structure: It has a long beak. There is
yellowish flattened crest above its beak. Its body
colour is brownish black. It has a long tail with
white colour. Its weight is about 3 to 3.5 kg. It is
hunted for its bone and fat.

Habitat: It is found in dense forest of Terai
region. It is an endangered bird of Nepal.

Food: It feeds on insects, fruits and small
vertebrates.

life span: Its life span is about 6 to 7 years.

Reasonable fact-1

Forest products are very important natural resources for human beings.
Firewood, wood, medicinal plants, grasses, fruits, etc. are forest products which are
essential for human beings. Plants provide food, oxygen and energy to the entire world.
Plants also provide fibre, building materials and so on.

Natural products like oil, latex, etc. are obtained from forest. Plants also help to control
soil erosion and landslides. They also provide habitat to wild animals. So, forest
products are very important natural resources for human beings.

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 347

Reasonable fact-2

National parks and Wildlife reserves help to conserve wildlife.
A national park helps in the conservation and management of natural environment
including wild animals, plants and landscapes together with their utilization. Similarly,
wildlife reserve protects endangered animals by conserving their habitats. So, national
parks and wildlife reserves help to conserve wildlife.

Project work

Visit a zoological garden (zoo) or any protected area near your locality. Collect
information on scientific name, food, habitat, body structure, life span, etc. of the
animals found in that place. Prepare a short report and submit to your science teacher.

SUMMARy

• The resources such as water, minerals, forest, fertile land, sunlight, wind, etc.
that exist in nature are called natural resources.

• Natural resources are the materials and components that can be found in the
environment.

• In Nepal, twelve National Parks, one Wildlife Reserve, six Conservation
Areas and one Hunting Reserve have been established so far.

• A National Park is an area set aside for the conservation and management of
natural environment including wild animals, plants and landscapes together
with their utilization.

• A separate reserved area for protection and proper management of endangered
wildlife is called a Wildlife Reserve.

• The protected area which is managed according to the plans for conservation
of natural resources, wildlife and their habitat, sustainable development and
use of natural resources is called Conservation Area.

• The reserved area established for licensed hunting is called Hunting Reserve.
• Various types of mammals, birds, reptiles, amphibians, timbers, medicinal

plants are found in the forests of Nepal.

• A variety of animals like tiger, rhinoceros, elephant, snow leopard, python,
dhanesh, vulture, etc. are being endangered due to destruction of habitat and
poaching.

• In Nepal, 26 mammals, 9 birds and 3 reptiles are classified by the IUCN Red
list of threatened species as 'endangered'.

348 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

Exercise

1. Choose the best answer from the given alternatives.

a. How many national parks have been established in Nepal?

i. eight ii. nine

iii. seven iv. ten

b. Which of the following wildlife reserves is located in Kanchanpur district?

i. Shukla Phanta Wildlife Reserve

ii. Parsa Wildlife Reserve

iii. Koshi Tappu Wildlife Reserve

c. Which of the following is the first national park of Nepal?

i. Shivapuri–Nagarjun National Park

ii. Chitwan National Park

iii. Bardiya National Park

iv. Sagarmatha National Park

d. Which of the following medicinal plants is banned for collection and export?

i. Panchaunle ii. Timur

iii. Bojho iv. Harro

e. How many species of mammals are protected in Nepal?

i. 36 ii. 16 iii. 26 iv. 6

2. Fill in the blanks with appropriate words.

a. Natural resources and human beings are ................... to each other.

b. In Nepal, forest covers only ................... of the land.

c. The only one hunting reserve of Nepal is ................... .

d. Api Nampa Conservation Area is located in................... district.

e. There are ................... types of medicinal plants in Nepal.

3. Answer the following questions.

a. What are natural resources? How can you show interrelation of human beings
with natural resources?

b. What are protected areas? Give any two examples.

c. What is a National Park? Name the 10 National Parks of Nepal.

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 349

d. What is a Wildlife Reserve? Name the Wildlife Reserves established in Nepal.

e. What are Conservation Areas? Name the Conservation Areas established in
Nepal.

f. What is meant by Hunting Reserve? Name the Hunting Reserve of Nepal.

g. Why do we need forest? Describe in brief.

h. What is the present status of forest in Nepal?

i. What are rare animals? Give any three examples.

4. Write short note on:

a. One-horned rhinoceros b. Gaint pied hornbill

c. Royal Bengal tiger d. Asiatic elephant

5. Give reason.
a. There is a close relationship between human beings and natural resources.

b. Wildlife is facing extinction due to human activities.

c. National parks, wildlife reserves and conservation areas help to conserve flora
and fauna.

d. Bengal tiger and Red panda are called endangered species.

e. We should conserve natural beauty and wildlife.

6. What effort have you made in your locality to conserve forest and wildlife?
Explain.

7. Differentiate between:

a. National Park and Wildlife Reserve

b. Wildlife Reserve and Hunting Reserve

c. Timber plants and Medicinal plants

8. What are medicinal plants? Name any five protected plants of Nepal.

9. Explain the present status of animals and birds in Nepal.

10. Write down the habitat of given animals.

a. Royal Bengal tiger b. Red panda c. Python

d. Giant pied hornbill e. One-horned rhinoceros

350 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

23UNIT Estimated teaching periods : Th Pr
6 1

ENVIRONMENTAl DEGRADATION
AND ITS CONSERVATION

Objectives

After completing the study of this unit, students will be able to:

• explain environmental pollution (air, water, land and sound pollution) and its effects.
• describe greenhouse effect and its impact on environment due to global warming.
• introduce climate change, its effects and describe local efforts to reduce climate

change.
• describe acid rain, its causes and effects.
• explain measures of environment conservation.
• introduce different natural disasters and their causes.
• explain the measures of disaster management and reduction.
• introduce and explain the role of NTNC, IUCN, WWF, UNEP and ICIMOD.

Course of Study

• Introduction to environmental degradation
• Impact of human activities on environment
• Environmental pollution (air pollution, water pollution and noise pollution)
• Greenhouse effect, causes and adverse effects
• Climate change, acid rain
• Disaster and disaster management
• Measures of environment conservation
• Introduction to NTNC, IUCN, WWF, UNEP and ICIMOD and their role in

environment conservation

Points to be Focused/Questions to be Discussed

• What is environment pollution? What are its types?
• What is greenhouse effect? What are its causes and adverse effects?
• What is acid rain? What are its adverse effects?
• What is meant by climate change?
• What are various measures to conserve environment?
• What is the role of NTNC, IUCN, WWF, UNEP and ICIMOD to conserve and

promote environment?

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 351

23.1 Introduction

A variety of environmental components like natural, biological, social, cultural, etc.
are found in our surroundings. Land, air, water, soil, minerals, etc. are the natural
components of the environment. Human beings are exploiting environment to meet their
requirements. Social norms and values, religions, customs, etc. are the social and cultural
aspects of the environment. This is called man-made environment. Various human
activities and natural disasters degrade the quality of the environment.

The damage or disturbance in any aspect of the environment due to human activities
and natural disasters is called environmental degradation. It results in adverse effects
in all living beings. Natural disasters like flood, landslide, earthquake, soil erosion,
etc. and human activities like deforestation, urbanization, etc. are the major causes of
environmental degradation. Destruction of forest, destruction of fertile land, degradation
in the quality of air, water and land, etc. are some examples of environmental degradation.

23.2 Effects of Human Activities on Environment

People use natural resources for their survival and development activities. They exploit
resources in excess to fulfill their needs. Overuse of natural resources results in many
adverse effects on environment. We have heard about river pollution, reduction in water
table, air pollution, noise pollution, etc. These are some examples of the adverse effects of
human activities on environment.

23.3 Environmental Pollution

Pollution is the introduction of contaminants into the natural environment that causes
adverse change. The contamination of the environment due to mixing of harmful and
unwanted substances which make environment impure is called environmental pollution.
Environmental pollution can be classified into following types:

1. Air pollution 2. Water pollution

3. Land pollution 4. Noise pollution

1. Air pollution Fig. 23.1 Air pollution

Air is the mixture of various gases.
It contains about 78.08% nitrogen,
20.94% oxygen, 0.93% argon and
0.03% carbon dioxide gas. If there
is mixing of foreign elements, their
ratio changes and the quality of air
degrades. The contamination of air
with unwanted and harmful sub-
stances is called air pollution. Air
pollution is caused due to mixing of

exploit / ɪkˈsplɔɪt / - to use sth well in order to gain as much from it as possible

352 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

harmful gases like carbon monoxide, sulphur dioxide, chlorofluro carbons, oxides
of nitrogen, etc. and dust particles in air. The unwanted and harmful substances like
smoke, dust particles and harmful gases released from vehicles and industries are
the major air pollutants.

Causes of air pollution

i. Burning of fossil fuels in industries releases smokes, dust particles and harmful
gases into the atmosphere. These substances cauase air pollution.

ii. Burning of plastics and rubber produces excessive amount of harmful gases like
carbon dioxide, carbon monoxide. These gases cause air pollution.

iii. In rural areas, agricultural residues are directly burnt in field. Similarly, local people
use traditional sources like firewood, dung cake, etc. to cook their food. These
activities cause air pollution.

iv. Polluted land, polluted water resources and decaying organic matter emit bad smell
in the surroundings which causes air pollution.

v. In deforested land, the dust particles are easily blown away by wind and cause air
pollution.

vi. The dust particles released during construction works also cause air pollution.

Effects of air pollution
i. Air pollution affects human health in various ways. It causes irritation to eyes and

affects nose, throat and upper respiratory tract. It may cause headache, nausea and
allergic reaction. Similarly, long-term health effects of air pollution include chronic
respiratory diseases, lung cancer, heart disease, tuberculosis, asthma, bronchitis,
skin diseases, etc.

ii. Air pollutants damage buildings and historical monuments when sulphur
pollutants fall on buildings made of limestone and sandstone. They react with
minerals in the stone and gradually corrode them.

iii. Harmful gases like sulphur dioxide, nitrogen oxide, etc. damage the leaves of crop
plants.

iv. Air pollution can cause acid rain which damages crop plants, trees, buildings, metal
structures, statues and historical monuments.

v. Air pollution results in global warming.

2. Water Pollution

About 71% of the earth's surface is covered by water. Despite that only less than 1%
water can be used for drinking. Rivers, streams, springs, waterfalls, lakes, etc. are
the sources of fresh water. Such sources are being polluted due to human activities.
As a result, the limited fresh water resources are also decreasing day by day.
Everyday many unwanted and harmful substances are thrown into rivers and lakes.

monument / ˈmɒnjʊmənt / - a building, column, statue, etc.

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 353

The contamination of rivers and lakes with unwanted and harmful substances
is called water pollution. Water is said to be polluted when it becomes unfit for
drinking and bathing due to an adverse change in physical, chemical or biological
condition. Polluted water is harmful to living beings.

Fig. 23.2 Water pollution

Causes of water pollution

i. Mixing of drainage directly into water bodies causes water pollution.

ii. Dumping of untreated sewage from the cities into rivers and lakes causes water
pollution.

iii. Discharging of untreated wastes like hospital wastes, industrial wastes, municipal
wastes, institutional wastes, etc. into the rivers or lakes causes water pollution.

iv. Defecation in open fields and near water sources causes water pollution.

v. Washing clothes and utensils and throwing of waste materials in the sources of
water cause water pollution.

vi. Excessive use of chemical fertilizers, pesticides and insecticides in agricultural land
causes water pollution.

vii. Bursting or cracking of drinking water pipes and drainage pipes causes water
pollution.

viii. Excessive use of synthetic detergents causes water pollution.

Effects of water pollution

i. Water pollution causes water-borne diseases like hepatitis A and E, diarrhoea,
cholera, ascariasis, typhoid, dysentery, etc.

ii. Hard water causes cardiovascular diseases.

iii. Drinking water with excessive level of nitrates lowers the oxygen carrying capacity
of the blood.

iv. Polluted water containing harmful chemicals like insecticides, pesticides damages
our health.

354 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

v. Water pollution lowers dissolved oxygen level which affects aquatic plants and
animals.

vi. Polluted water spreads bad smell and causes air pollution.

3. land Pollution

Land is the part of the earth that

is not covered by water. The

surface layer of land is called

soil. Soil is a renewable resource.

But it is produced very slowly.

Various human activities are

responsible for land pollution.

The contamination of land due

to accumulation of harmful

substances and waste materials

that changes the composition Fig. 23.3 Land pollution

of soil is called land pollution.

Various human activities are responsible for land pollution.

Causes of land pollution

i. Excessive use of chemical fertilizers and insecticides in agricultural fields causes
land pollution.

ii. Dumping of household solid wastes from cities on soil causes land pollution.

iii. Disposal of industrial and agricultural wastes causes land pollution.

iv. Throwing non-degradable waste causes land pollution.

v. Use of polluted water for irrigation also causes land pollution.

Effects of land pollution

i. Land pollution decreases the fertility of soil and thus decreases crop production.

ii. It causes adverse effects on soil organisms.

iii. Polluted land spreads bad smell and causes air pollution.

iv. Polluted land causes ground water pollution.

v. Land pollution causes contamination of crops.

4. Noise pollution

Noise pollution is the unwanted sound produced at a wrong place and wrong time.
Machinery equipment, traffic, crowd, social activities, musical instruments, etc. are
the sources of noise in our surroundings.

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 355

Causes of noise pollution

i. Noise is produced due to a variety of machinery equipment in industries and
construction sites.

ii. Road traffic, rail traffic, air traffic, etc. cause noise pollution.

iii. Densely populated settlement produces much sound and causes noise pollution.

iv. In city areas, there is publicity of different news through loudspeakers which causes
noise pollution.

v. Playing musical instruments in high volume also causes noise pollution.

Effects of noise pollution Fig. 23.4 Noise pollution
i. Noise causes hearing loss, irritability and

loss of cencentration.

ii. It decreases working efficiency.

iii. It increases mental tension.

iv. It increases blood pressure.

v. It causes insomnia, migraine and
headache.

vi. It results in psychological disorder and
nervous tension.

vii. It may rupture the ear drum and cause deafness.

23.4 Greenhouse Effect

Different types of gases like carbon dioxide,
chlorofluorocarbon, methane, oxides of nitrogen, water
vapour, etc. are present in the atmosphere. These gases
cover the earth's surface making dense canopy similar
to the glass frame of an artificial greenhouse. This dense
canopy of different gases allows the solar radiations
to enter into the earth surface but does not allow
them to escape out after reflection. As a result, these
solar radiations absorbed in the atmosphere increase Fig. 23.5 Artificial greenhouse
temperature of the earth. The phenomenon of increasing
the temperature of the earth as in artificial greenhouse is called greenhouse effect. The
gases which are responsible for the greenhouse effect are called greenhouse gases. The
temperature of the earth is increasing gradually due to greenhouse effect. This process
is called global warming. According to the researches, the temperature of the earth has
increased less as compared to that of the polar region. As a result, a large mass of ice in the

insomnia / ɪnˈsɒmnɪə / - the condition of being unable to sleep
migraine / ˈmiːɡreɪn / - a very severe type of headache
canopy / ˈkænəpi / - a layer that spreads over an area like a roof

356 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

polar caps melts which increases the level of the sea. It affects the lives of people in coastal
areas. Similarly, the temperature of higher regions is increasing more as compared to the
lower regions due to the drying of the water resources and reduction in the amount of ice
in the Himalayan region.

Sources of greenhouse gases

The greenhouse gases are released from different human activities as well as by some
natural processes. Some of them are listed below:
1. Carbon dioxide gas (CO2) is produced by burning of fossil fuels (like coal, oil, natural

gases), industrial activities, automobiles, aircrafts, etc.

2. Methane (CH4) is produced from the decomposition of domestic wastes and sewage.
3. Chlorofluorocarbon (CFC) is released from refrigerators, air conditioners, aerosol

spray cans, etc.

4. Water vapour (H2O) is released from the oxidation of organic compounds as well as
vaporization of water from water sources.

Importance of greenhouse effect

If there were no greenhouse gases in the atmosphere, all the solar radiations entering the
earth surface would escape into the space. As a result, heat would not be stored in the
earth. Consequently, the temperature of the earth would be less by –180 C than today's
temperature. Ice would cover the earth and there would not be any organism on the earth.
So, greenhouse effect is very important for existence of lives on the earth.

Adverse impact of greenhouse effect

Due to various human activities, the concentration of greenhouse gases is increasing day
by day. It increases the temperature of the earth. The adverse impact of greenhouse effect
are given below:

1. Effects on animals

i. It helps to spread different types of diseases like malaria, filariasis, cholera,
diarrhoea, etc.

ii. It helps to increase the number of pathogenic insects.

2. Effects on plants

i. It affects water cycle, soil moisture and soil composition. As a result, there is a
change in the cultivation and harvesting periods.

ii. Due to the effect of global warming, tropical plants are seen in the temperate
region.

iii. It helps in breeding, growth and development of disease causing insects.

pathogenic / ˈ p æ θ ə d ʒ ə n I k / - related to things that cause diseases

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 357

3. Effects on climate

i. It increases the temperature of the earth.

ii. It causes melting of ice in the polar region, which increases the sea level and
may submerge the low land areas of the earth.

iii. It changes the pattern of rain fall and weather condition.

Ways of controlling greenhouse effect

Greenhouse effect can be controlled by:
i. Decreasing deforestation and increasing afforestation.
ii. Reducing the use of fossil fuels like petrol, diesel, kerosene, coal, etc.
iii. Banning the production and use of CFCs.
iv. Using solar energy, wind energy, biogas, etc.

Difference between Natural greenhouse and Artificial greenhouse

Natural greenhouse Artificial greenhouse

1. Some of the gases (e.g. carbon dioxide, 1. The artificial house made in gardens
methane, etc) in the lower atmosphere using glass or plastics is called artificial
cover the earth in the form of dense greenhouse.
canopy like an artificial greenhouse,
which is called natural greenhouse.

2. The possibility of all living organism on the 2. Growth of different plants like vegetables,

earth is the result of natural greenhouse. flowers, etc. in off seasons and growth of

summer plants in winter season are the

results of artificial greenhouse.

23.5 Climate Change Fig. 23.6

Climate is the atmospheric phenomenon over a long
period of time. Climate change refers to the variation in
the earth's global climate or in regional climate over time.
Human beings are responsible for change in the climate
of a region. The main factor for climate change is increase
in level of carbon dioxide in the atmosphere. Over use
of fossil fuels, deforestation, burning of firewood, forest
fire, etc. increase concentration of carbon dioxide in the
atmosphere.

Effects of Climate Change
i. It causes loss of biodiversity.

ii. It decreases agricultural production and changes the crop pattern.

358 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

iii. It melts snow in polar region and the Himalayan region.
iv. It increases the level of sea, due to the melting of ice in the polar region.
v. It decreases the amount of fresh water.
vi. It affects the global water cycle.
vii. It changes wind circulation and affects the pattern of rainfall of a particular place.
viii. It causes improper distribution of rainfall.

23.6 Acid Rain

Various industrial gases like carbon dioxide, sulphur dioxide, sulphur trioxide, nitric
oxide, nitrogen dioxide, nitrogen pentoxide form acids when they react with water of
the atmosphere. When those acids get mixed with rain and fall down in the form of rain,
it is called acid rain. The rain containing small amount of acids formed form gases like
oxides of sulphur nitrogen, etc. present in atmosphere is called acid rain. The process of
formation of acids in atmosphere is given below:

Formation of Sulphuric acid (H2SO4)

2SO2 + O2 2SO3

SO3 + H2O H2SO4 (Sulphuric acid)

Formation of Nitric acid (HNO3)

NO + O3 NO2 + O2
4NO2 + O2 2N2O5
N2O5 + H2O 2HNO3 (Nitric acid)

Formation of Carbonic acid (H2CO3)

H2O + CO2 H2CO3 (Carbonic acid)

The acids like H2SO4, HNO3, H2CO3, etc. get mixed with rain and fall down on the earth
in the form of acid rain.

Effects of acid rain

i. Acid rain corrodes historical monuments like
statues, sculptures of metals, marble, etc.

ii. Acid rain increases the acidity of soil and
reduces the production of crop.

iii. Acid rain increases the acidity of water Fig. 23.7
and may kill the aquatic animals and
plants.

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 359

iv. Acid rain causes different types of skin and respiratory diseases in human beings
and other animals.

Control measures of acid rain
i. The emission of industrial gases should be minimized.
ii. The use of alternative energy should be increased.
iii. Industrial gases like SO2 and CO2 should be reused before emission from industries.
iv. The use of clean fuels should be increased.

v. Pollution control devices should be developed and installed in industries.

23.7 Disaster and Disaster Management

During rainy season, various kinds of disasters like flood, landslide, etc. occur every year
in different parts of Nepal. In hot and dry summer season, fire is common throughout
Nepal. Floods, landslides, fire, earthquake, etc. are called natural disasters. A disaster is
a sudden calamitous event that seriously interrupts the functioning of a community or
a society involving widespread human material, economic or environmental losses and
impacts. Disasters are mainly of two types. They are:

i. Natural disasters ii. Human induced disasters

i. Natural disasters

Natural disasters are natural processes or phenomena that may cause loss of life,
injury or other health impacts, property damage, loss of livelihoods, social and
economic disruption or environmental damage. Earthquake, landslide, volcanic
eruption, floods, tsunamies, cyclones, etc. are some examples of natural disasters.

ii. Human induced disasters

Human induced disasters are the disasters resulting from human activities. Fire
desertification, road accident, oil spills, nuclear explosion, etc. are some common
human induced disasters.

Causes of Disasters

Various factors are responsible for disasters. Flood, landslide, soil erosion, forest fire, etc.
occur due to both natural as well as human causes. In Nepal, the geological structure is
fragile. So, landslides are common in the Siwalik range. There is rapid deforestation in
hilly region. Every year people from different parts of Nepal have to face landslides and
floods. In Mahabharat range, there are frequent incidents of lightning.

23.8 Management and Mitigating Measures of Disasters

Disasters are caused by various factors. Therefore, the management of disasters and their

fragile / ˈfrædʒaɪl / - easily broken or damaged

360 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

mitigating measures should be designed on the basis of causes of disasters.

The main mitigating measures of disasters are mentioned below:
i. Development of public awareness
ii. Rescue of the affected people
iii. Mobilization of help in a proper way
iv. Help, rehabilitation and relief to the affected people

1. Management and mitigating measures for earthquake

The sudden shaking of the earth’s surface
is called earthquake. It occurs due to
sudden release of energy in the earth’s
surface. An earthquake is the vibration of
the earth’s surface. The vibration may be
up and down or left and right.

Nepal is situated in the active earthquake

region. In Nepal, earthquake has occurred

several times. In 1990 B.S., a devastating Before earthquake After earthquake
earthquake occurred with a magnitude
Fig.23.8 (a)

of 8.3 Richter scale. It killed 8519 people

and destroyed thousands of houses and buildings. Similarly, the earthquake that

occurred in 2045 B.S. killed 721 people and damaged 65,000 houses and buildings.

Its magnitude was 6.6 Richter scale. On 12 Baisakh 2072, at 11:56 AM local time,

devastating earthquake of about 7.6 magnitude struck in Nepal, with epicentre in

Barpak VDC of Gorkha district. This tolled thousands of death and injuries leaving

millions of people displaced from rural hilly areas and Kathmandu Valley. Many

after shocks were continued and majority of population remained outside the house

at least for 4-5 nights. The districts of western and Central Development Region

including Kathmandu Valley were highly affected by the earthquake. The earthquake

killed more than 8,500 people, injured 16033 and damaged 416359 houses. Several

villages in rural areas, public and historic buildings of Kathmandu Valley were

collapsed and damaged due to the earthquake. The earthquake may occur at any

time. Therefore, we should adopt various measures to be safe from the earthquake.

Preventive measures before earthquake
i. Identify a safe place inside and outside the house.
ii. Repair wall, ceiling, electric wires, foundation of house on time.

iii. Keep the first aid box properly.

iv. Keep television, cupboard, frames, refrigerators, mirror, etc. fixed to the wall
in such a way that they don't fall down during an earthquake.

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 361

Preventive measures during an earthquake

i. Stop vehicle and be in an open place if you are
inside the vehicle.

ii. Be in a safe place if you are outside.
iii. Be in a safe place if you are inside house.

iv. Do not hurry and run. Fig. 23.8 (b)
v. Do not stay near the cupboard or any other

object that can fall and injure you.
vi. Switch off electric appliances.

Measures to be adopted after earthquake

i. Go to a safe place and do not enter the house immediately after an earthquake.

ii. Support the victims of the earthquake.

iii. Check the condition of your house before entering.

iv. Listen to emergency news of the earthquake broadcast by radio/TV and behave
accordingly.

2. Management and mitigating measures for flood and landslide

The level of water in rivers, streams, seas, etc. increases due to heavy rainfall,
melting of snow lakes (glaciers), earthquake , etc. The overflow of water on the right
and left sides of rivers, streams, seas, etc. is called flood. It damages a lot of lives

and property especially in the Terai region of Nepal. Flood destroys cultivated land,

vegetation, human settlement, roads, bridges, etc.

Flood Fig. 23.9 Landslide

During the rainy season, the parts of land, soil, rock, etc. fall downwards due to
the effect of gravity. This natural disaster is called landslide. The sudden slide of
land, rocks and soil downwards due to the effect of gravity is called landslide. It
damages life and property in Himalayan and hilly regions of Nepal. Heavy rainfall,
deforestation, earthquake, overgrazing, unscientific agricultural techniques, etc. are
responsible for landslide. We should adopt various measures to be safe from flood

and landslides.

362 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

Management and mitigating measures for flood and landslide
i. Stay in a safe place.
ii. Do not cross the flooded river.
iii. Inform the seniors or elders if a river is blocked.
iv. Help the victims of flood and landslide.
v. Dispose the dead bodies of animals properly after flood.

Management of flood and landslide
i. Build embankment on either side of the river.
ii. Encourage terrace farming.
iii. Do not build houses and buildings on slopes.
iv. Identify flood and landslide-prone areas.
v. Conduct plantation programme on the bare land.

3. Management and mitigating measures for fire
The condition in which flames go out of control and destroy lives and property is
called fire. If the fire catches the forest, it is called forest-fire or wild fire. Every year,
fire destroys a lot of lives, property, human settlement and forest in our country. Fire
mainly occurs in hot and dry summer in Terai and hilly regions of Nepal.

Main causes of fire

i. Thunder and volcanic eruption are natural
causes of fire.

ii. Misuse of fire by children, throwing cigarette Fig. 23.10 Forest fire
butts carelessly after smoking, short circuit, etc.
are the human causes of fire.

Main effects of fire

i. Fire destroys human settlement.
ii. Fire damages lives and property.
iii. Forest fire damages wildlife and vegetation.
iv. Fire causes environmental pollution.
Following measures are to be adopted to be safe from fire:
i. Keep matchsticks and lighter away from the reach of children.
ii. Do not smoke in forest in summer.
iii. Manage fire brigade and check household wiring system.
iv. Develop public awareness.
v. Extinguish fire properly.

vi. Support fire victims.

vii. Do not throw cigarette butts after smoking.

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 363

4. Management and mitigating measures for epidemics
Epidemic is the rapid spread of infectious disease among a large number of people

in a given population within a short period of time. It kills a large number of people
within a short period of time. It affects lives and property.

Following mitigating measures should be adopted to control and manage epidemics.

i. Spread awareness about epidemics.

ii. Conduct sanitation programmes.

iii. Keep your surroundings clean.

iv. Pay attention to personal hygiene.

v. Keep water resources free from pollution.

vi. Arrange treatment for victims.

vii. Follow precautions of epidemics.

23.9 Environment Conservation Measures

Environment and development are interrelated to each other. There is a need of
environmental resource to conduct development works. Water resource, mineral resource,
land resource, forest resource, etc. are utilized to carry out development activities. It is
not possible to conduct development works in the absence of natural resources. But it
should be noted that environmental resources should be utilized in a proper manner.
The resources should not be overexploited. It contributes to conservation of environment.
Following measures can be adopted to conserve environment.

i. Public Awareness

Increasing population requires more food, more fuel, more clothes, more space for
settlement and so on. It results in environmental degradation. Therefore, we should
generate public awareness among the people to control population growth and
conserve the environment.

ii. Conservation of water resources

Rivers, ponds, lakes, streams, springs, snow, well, etc. are the major sources of water.
We should conserve these sources. We should plant trees near the sources of water.
We should not throw waste materials near the sources of water. We should conduct
cleaning campaigns and prevent water resources from being polluted. We should
not mix industrial wastes, chemical fertilizters, insecticides, etc. with the sources of
water. We should not wash clothes and utensils, bathe and defecate near the sources
of water. We should manage and utilize the sources of water properly.

iii. Conservation of soil

Soil is an important natural resource. We should conserve soil in its natural state
to preserve its fertility. It also helps to conserve environment. We should plant

364 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

trees on barren land. Similarly, plantation should be done near the sources of
water. We should control overgrazing. We should control deforestation and
promote afforestation to conserve land. Terrace farming should be practised
in slopes and hilly regions. Similarly, dams and walls should be constructed
to reduce soil erosion. We should use compost manure and reduce the use of
chemical fertilizers and insecticides. We should manage solid wastes properly.

iv. Public participation

We should involve as many people as possible to conserve environment. People’s
participation increases responsibility of local people to conserve environment and
the conservation of environment also becomes easier and meaningful.

v. Afforestation and conservation of forest

Deforestation is a major environmental problem. We should conduct afforestation
programmes in slopes, barren fields, etc. Plantation in slopes and landslide-affected
areas prevents soil erosion. Forests are important natural resources. It is our duty to
conserve forests.

vi. Environmental sanitation and pollution control

Increasing population is the major cause of environmental pollution. Increasing
population demands more natural resources. Increasing means of transportation
increase air pollution. We should perform following activities to conserve
environment by environmental sanitation and controlling pollution.

i. We should keep our surroundings clean.

ii. We should manage the household wastes properly.

iii. We should conserve water resources.

iv. We should use gobar gas (bio-gas) and solar energy for fuel.

v. We should conduct sanitation programmes in our locality.

vii. Conservation and promotion of cultural resources

Nepal is rich in cultural resources. Various human activities bring out changes in
the forms of those resources. Therefore, we should make policies to conserve and
promote cultural resources.

In this way, we can contribute a lot to conserve environment by conducting various
activities and programmes in our locality.

Activity 1

• Visit a place in your locality which is affected by landslide, flood or soil erosion.
Observe the situation around it and find out the causes and effects of that
disaster. Prepare a report and submit it to your subject teacher.

• What type of activities are being conducted in your locality to conserve
environment? Prepare a short report and submit it to your subject teacher.

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 365

23.10 National and International Agencies Involved in
Environment Conservation and Promotion

Environmental pollution and degradation is a global problem. It is the responsibility of
human beings to conserve environment. Various national and international organizations
and agencies are involved in environment conservation. The organizations and agencies
involved in conservation and promotion of environment in Nepal are given below:

1. National Trust for Nature Conservation

National Trust for Nature Conservation (NTNC) is an

autonomous non-governmental organization of Nepal. It was

established in 1982 to work in the field of nature conservation

and sustainable development. The trust is supported by a

network of international partners. NTNC has successfully

undertaken many small and large projects on nature

conservation, biodiversity, tourism, development management Fig. 23.11
and sustainable rural development. At present, NTNC manages

Annapurna Conservation Area Project (ACAP) and Manaslu

Conservation Area Project (MCAP) together with other projects in and around

national parks and wildlife reserves.

2. International Union for Conservation of Nature (IUCN)

The International Union for Conservation of Nature (IUCN) is Fig. 23.12
an international organization founded in October 1948, France.
In Nepal, it was established in 1994 AD, but it has been working
in Nepal since 1970 AD. It focuses on nature conservation,
biodiversity and nature-based solutions. The mission of IUCN is
to influence, encourage and assist societies throughout the world
to conserve nature and natural resources.

IUCN focuses on study of status of environment, policy making and sustainable
development. It publishes IUCN red list of threatened animals and spreads scientific
knowledge regarding endangered species. IUCN helps Nepal to design curriculum
and publish books, construct educational materials, frame environmental policy to
conserve forest and wildlife; and to manage National Parks and Wildlife Reserves.

3. World Wide Fund for Nature (WWF) Fig. 23.13

The world wide fund for nature (WWF) formerly named as
World Wildlife Fund, is an international non-governmental
organization. It is working on issues regarding the
conservation, research and restoration of the environment. It
was established in April 29, 1961 in Morges, Switzerland.

WWF is the world’s largest independent conservation
organization with over 5 million supporters worldwide,

harmony / ˈhɑːməni / - a state of peaceful existence

366 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

working in more than 100 countries including Nepal. WWF opened its office in 1993
in Nepal and started working here.

The main mission of WWF is to stop the degradation of the planet’s natural
environment and to build a future in which humans live in harmony with nature by
• conserving the world’s biological diversity.
• ensuring that the use of renewable natural resources is sustainable.
• promoting the reduction of pollution and wasteful consumption.

4. Global Environment Fund (GEF) Fig. 23.14

Global Environment Fund is an international organization
founded in 1990 AD. It was founded on the principle that
well-mobilized capital can bring significant improvement in
the environment and quality of life throughout the world. The
mission of GEF is to conserve energy, environment and natural
resources.

5. United Nations Environment Programme Fig. 23.15

The United Nations Environment Programme (UNEP) is the
agency of the UN that coordinates United Nations Environment
Activities. It was founded in June 1972. It assists developing
countries including Nepal in implementing environmentally
sound policies and practices.

6. ICIMOD

International Centre for Integrated

Mountain Development (ICIMOD) is

a regional inter governmental learning

and knowledge sharing centre. It is an Fig. 23.16
international independent organization.

ICIMOD serves eight regional member

countries of the Hindu Kush Himalayan area, viz. Afghanistan, Bangladesh, Nepal,

Pakistan, Bhutan, China, India and Myanmar and the regional mountain community.

It was founded in 1983 AD. The central office of ICIMOD is located in Khumaltar,

Lalitpur of Nepal. ICIMOD is committed to a shared vision of prosperous and

secure mountain communities committed to peace, equity and environmental

sustainability. Its mission is to develop and provide integrated and innovative

solutions in cooperation with national, regional and international partners, which

foster action and change for overcoming mountain people's economic, social and

physical vulnerability.

equitable / ˈ e k w ɪ t ə b l / - fair and reasonable

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 367

The vision of the ICIMOD is "Men, women and children of the Hindu Kush
Himalayas enjoy improved well being." Similarly, the mission of the ICIMOD is to
enable sustainable and resilient mountain development for improved and equitable
livelihoods through knowledge and regional co-operation.

Reasonable fact-1

Public awareness helps a lot to conserve environment.

Until and unless people are made aware of conservation of environment, they do
not take part in conservation activities. They should be made aware of the need and
necessity of environment resources. Once they become aware of the importance of
conservation, they actively participate in conservation activities. So, public awareness
helps a lot to conserve environment.

Reasonable fact-2

Human activities are responsible for environmental degradation.

People depend on forest resources to fulfill their needs. They use trees to construct
houses. They cut trees to get firewood. They encroach forestland to expand their
agricultural land and settlement which leads to deforestation. Similarly, unwanted and
harmful substances like smoke, dust particles, mixing of drainage directly into water
bodies, excessive use of chemical fertilizers, pesticides and insecticides in agricultural
land, dumping of untreated sewage from the cities into rivers, dumping of household
solid wastes from cities on soil, throwing non-degradable waste, etc. are the human
activities which are responsible for environment pollution. These activities degrade
the environment. So, human activities are responsible for environmental degradation.

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SUMMARy

• The damage or disturbance in any aspect of the environment due to human
activities and natural disasters is called environmental degradation.

• An undesirable change in the physical, chemical or biological characteristics
of water that can adversely affect the health of living beings is called water
pollution.

• The phenomenon of increasing the temperature of the earth as in artificial
greenhouse is called greenhouse effect.

• The temperature of the earth is increasing gradually due to greenhouse effect.
This process is called global warming.

• The rain containing small amount of acids formed from gases like oxides of
sulphur and nitrogen, etc. present in atmosphere is called acid rain.

• The sudden shaking of the earth’s surface is called earthquake. It occurs due
to sudden release of energy in the earth’s surface.

• The overflow of water on the right and left sides of rivers, streams, seas, etc.
is called flood.

• The sudden slide of land, rocks and soil downwards due to the effect of
gravity is called landslide.

• The condition in which flames go out of control and destroy lives and property
is called fire.

• Various national and international organizations and agencies are involved in
environment conservation.

• The organizations and agencies involved in conservation and promotion of
environment in Nepal are: National Trust for Nature Conservation (NTNC),
International Union for Conservation of Nature (IUCN), Worldwide Fund
for Nature (WWF), Global Environment Fund (GEF), United Nations
Environment Programme (UNEP) and International Centre for Integrated
Mountain Development (ICIMOD).

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 369

Exercise

1. Choose the best answer from the given alternatives.

a. The percentage of nitrogen in air is .......................... .

i. 21% ii. 78.08% iii. 0.03% iv. 87.08%

b. Which of the following gases are greenhouse gases?

i. Carbon dioxide, methane and ozone

ii. Oxygen, nitrogen and carbon dioxide

iii. Carbon dioxide, methane and nitrogen

iv. Nitrogen, oxygen and methane

c. Climate is the atmospheric phenomenon for a .................... period of time.

i. short ii. long

iii. medium iv. very short

d. Which of the following is not a human induced disaster?

i. earthquake ii. flood

iii. landslide iv. forest fire

e. NTNC was established in ........................... AD.

i. 1981 ii. 1989 iii. 1982 iv. 1971

2. Fill in the blanks using appropriate words.

a. People use natural resources for their ........................... .

b. Burning of fossil fuels causes ........................... pollution.

c. Greenhouse gases are responsible for ........................... .

d. Natural disasters are natural processes that may cause ........................... .

e. Epidemic is the ......................... spread of ......................... diseases.

3. Answer the following questions.

a. What is environmental degradation? Mention any three natural causes of
environmental degradation.

b. What is environmental pollution? Write any three causes and three effects of
environment pollution.

370 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

c. What is air pollution? Write any three causes and effects of air pollution.

d. What is land pollution? Mention any four effects of land pollution.

e. What are greenhouse gases? Name them.

f. Write down the adverse effects of noise pollution.

g. What is meant by acid rain? Write down its effects.

h. What is global warming? Write down its cause.

i. What is meant by climate change? Write down its effects.

j. What are natural disasters? Give any two examples.

k. What is an earthquake? Write down its preventive measures.

l. What are the mitigating measures for flood, earthquake and fire?

4. What are the environmental conservation measures? Explain.

5. Write short notes on:

a. IUCN b. ICIMOD c. NTNC

d. WWF e. GEF f. UNEP

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 371

24UNIT Estimated teaching periods : Th Pr
8 2

ENVIRONMENT AND
SUSTAINABlE DEVElOPMENT

Objectives

After completing the study of this unit, students will be able to:
• introduce biodiversity and its types.
• explain the principle of sustainable development.
• describe global efforts for sustainable development and importance of

sustainable development.

Course of Study
• Introduction to biodiversity and its types
• Introduction to sustainable development
• Principles of sustainable development
• Global efforts for sustainable development
• Importance of sustainable development

Points to be Focused/Questions to be Discussed
• What is environment?
• What is sustainable development?
• What is biodiversity? What are its types?
• What are the principles of sustainable development?
• What are the global efforts for sustainable development?
• What is the importance of sustainable development?

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24.1 Introduction

Our surrounding consists of physical world and biological world. The physical and
biological world where we live is called environment. It is a natural world in which human
beings, animals and plants live together. Our environment consists of physical surroundings
including climatic factors and living organisms. The physical surroundings which
make up the environment are air, soil and water. The climatic factors that form a part of
environment are sunlight, temperature, pressure, rainfall, wind, etc.

Environment is the totality of physical, biological, natural, social, economic, chemical and
cultural aspects. It is clearly seen that there is a continuous interaction between or among
these aspects. The change or interaction between or among these aspects is responsible
for the change in environment. Therefore, we can say that there is a continuous change
in environment due to the change in its components. Human beings are also a part of
the environment. All activities of human beings have a great impact on the environment.
Today we do not live in a natural environment as we have modified it to suit our needs.

Differences between Development and Sustainable development

Development Sustainable development

1. It is a process by which members of society 1. It is the development that meets the needs

increase their personal and institutional of the present without compromising the

capabilities. ability of future generations to meet their

own needs.

2. Development meets the needs of the 2. Sustainable development meets the needs

present generations only to meet their of the present generation and future

own need. generation without compromising the

ability to meet their own need.

24.2 Biodiversity

A variety of plants and animals are found in our surroundings. The plants and animals
are different from each other. Plants and animals are different in shape, size, behaviour,
habitat, life cycle, reproduction, etc. Their diversity and types of ecosystems explain
biodiversity. It is diversity in life. Biodiversity is the degree of variation of life. It is a
measure of the variety of organisms present in different ecosystems. It should be noted
that biodiversity is the short form of biological diversity.

24.3 Types of Biodiversity

Biodiversity refers to the genetic variation, ecosystem variation and species variation within
an area, biome or earth. Hence, biodiversity can be mainly classified into three types.

i) Ecosystem diversity

Ecosystem diversity refers to the diversity of a place at the level of ecosystems.
Ecosystem diversity is the variation on the self-sustaining systems in which there is

biodiversity /ˌbaɪəʊdaɪˈvɜːsəti / - the existence of large number of plants and animals

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 373

interaction between biotic and abiotic components. There are mainly two types of
ecosystems, viz. terrestrial and aquatic. Aquatic ecosystems include river, stream,
lake, pond, sea, ocean, etc. whereas terrestrial ecosystems include forest, grassland,
desert, shrubland, etc. It is recorded that there are 118 different types of ecosystems
in Nepal. Due to climatic and geographical variation, various kinds of ecosystems
are found in Nepal. Similarly, different types of animals are found in Nepal due to
ecosystem diversity.

ii. Species diversity

Species is the group of individuals

which can freely interbreed with each

other to produce fertile offspring.

There are different kinds of species

in our surroundings. Cow, goat, dog,

cat, etc. are some examples of animal Fig. 24.1 Species diversity
species. Mustard plant, wheat plant,

rice plant, etc. are some examples of plant species. Plants and animals are different

within themselves. Cows and buffaloes both are mammals but they have so many

dissimilar characteristics. So, cows and buffaloes are kept in different species. It is

the variation in the group of individuals which can interbreed freely with each other.

The variation among the organisms of different species is called species diversity.

iii. Genetic diversity Fig. 24.2

Genes are the hereditary units that transfer parental
characteristics to their offspring. Genes are located in
chromosomes. Children have characteristics similar to
their parents. These characteristics are called hereditary
characteristics. But, there is variation among the children of
the same parents. Such variation is called genetic diversity.
Genetic diversity is the variation in the hereditary units
that transfer parental characteristics to their offspring.
Genetic diversity depends on the population of the
organisms. Genetic diversity refers to the variation among
the members of the same species, e.g. Nigro, Mangol,
Aryan, etc.

Differences between Ecosystem diversity and species diversity

Ecosystem diversity Species diversity

1. It is the variation on the self sustaining 1. It is the variation among the organisms of
systems in which there is interaction different species.
between biotic and abiotic components.

2. It refers to the diversity of a place at the 2. It refers to the variation of different kinds

level of an ecosystem. of species in our surroundings.

hereditary / h ə ˈ r e d ɪ t r i / - given to an offspring by its parents before it is born

374 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

Differences between Species diversity and Genetic diversity

Species diversity Genetic diversity

1. It is the variation among the organisms of 1. It is the variation in the hereditary units

different species. that transfer parental characteristics to

their offspring.

2. It refers to the variation of different kinds 2. It refers to the variation among the

of species of our surroundings. members of the same species.

Activity 1

• Visit a nearby ecosystem with your science teacher. Identify various kinds of species
found in that ecosystem. Prepare a short report on it and submit to your science teacher.

24.4 Principles of Sustainable Development

Human beings carry out various kinds of development projects on the earth. They
build houses, construct roads, bridges, canals, etc. on the earth. For this purpose, they
use resources available in the earth. Therefore, all development works are carried out
on the earth by using the resources available in the environment. Thus, there is a close
connection between environment and development projects.

All the development works are carried out for the benefit of human beings. These works
promote economic, social and cultural aspects of human beings. Therefore, it is necessary
to use the resources available in the environment for the benefit of human beings. Human
beings use land, water, air, etc. from the environment for various purposes. But it is also
necessary to analyze the effect of human activities on natural environment. On the basis
of this analysis, it is necessary to use the resources by conserving the natural environment.

In 1983 AD, World Conference related to environment and development published a report
called "Our Common Future." This report emphasized on sustainable development. As a
result, the concept of sustainable development has got worldwide importance in the field
of development. At present, the importance of sustainable development has increased in
various development sectors.

Sustainable development is the combination of two words 'sustainable' and 'development'.
'Sustainable' means 'capable of being around for a long time' and 'development' means
'growth.' Therefore, sustainable development is defined as the development that meets
the needs of the present without compromising the ability of future generations to meet
their own needs. In other words, sustainable development is related to those development
activities which do not degrade the environment and can be carried on for a long time.
Thus, sustainable development includes:

i. living within the limits of consumption of natural resources,

ii. realizing the interconnections among various developmental aspects and
environment, and

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 375

iii. equitable distribution of resources and opportunities.

Therefore, sustainable development refers to the use of natural resources at present
without damaging their condition for the future generations.

The main principles of sustainable development are discussed below:

i. Conservation of ecosystem

There are mainly two types of ecosystem on the earth. They are aquatic and terrestrial
ecosystem. When there is conservation of the aquatic and terrestrial ecosystem, there
is conservation of the earth itself. Hence, ecosystem should be conserved.

ii. Development of sustainable society

Healthy habitat, balanced diet, health services, quality education and job opportunities
are some elements of sustainable society. These elements develop positive attitude
towards the nature and motivate people for conservation of environment.

iii. Conservation of biodiversity

Conservation of biodiversity is a must for sustainable development. Conservation
programmes should be conducted at local, national and global level.

iv. Control of population growth

Population growth should be controlled for meeting the goal of sustainable
development. It means that balance should be maintained between population
growth and environmental resources.

v. Development of human resource

There is a need of development of human resource for sustainable development. It
is because only trained, qualified or skilled manpower can implement the principles
of sustainable development in an effective manner.

vi. Increase public participation

Public participation is necessary for sustainable development. With an increase in
public participation, objectives of sustainable development can be easily achieved.
There is a need of joint effort of all the people in conservation programmes.

vii. Conservation of cultural heritages

Cultural heritages are the important aspects of the environment. Conservation of
cultural heritages contributes to implement principles of sustainable development.

viii. limit of carrying capacity

Carrying capacity of the earth means the maximum number of individuals that the
earth can sustain. Human activities should be conducted within the carrying capacity
of the earth. That means, people should understand the regeneration processes of
the mother nature.

alleviate / əˈliːvɪeɪt / - to make sth less severe

376 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

Activity 2

Observe any one of the development works among road, bridge, building, etc. in
your locality. On the basis of your observation, find out the answers to the following
questions:
• What natural resources are used in that development work?

• What are the adverse effects of that development work on the environment?
On the basis of the solutions to above questions, prepare a short report and submit
it to your teacher.

24.5 Global Efforts for Sustainable Development

Late in 1983, the Secretary – General of the United Nations asked Norway's Mrs Gro
Harlem Brundland – the only politician in the world to proceed from the post of
Environment Minister to Prime Minister to put together an independent commission. In
April, 1987 the commission published Our Common Future. Its main task was to come up
with a global agenda for change. Similarly, there was a conference on Environment and
Development in Rio de Generio in 1992. It emphasized sustainable development. World
Food Organization has given priority to conservation and management for fulfilling the
needs of future generations. Globally, following points are considered for sustainable
development:

i. Pollution control

ii. Conservation of biodiversity

iii. Conservation of ecosystem

iv. Promote investment in environmental sector

v. Management of natural resources and protection of nature

vi. Population control and poverty alleviation

vii. Formation of NGOs and community groups

viii. Conservation for future generation

ix. Implementation of policies for sustainable development

24.6 Importance of Sustainable Development

Sustainable development is the development that can be maintained for a long time. Therefore,
human beings can take benefit from sustainable development for a long time. Sustainable
development does not degrade the environment. It helps maintain the natural resources for
a long time. As a result, environment remains in balanced condition. It does not affect the life
cycle of the living beings. Thus, sustainable development is the need of the world. The benefit

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 377

of sustainable development can be achieved in local, national and international level. Some of
the benefits of sustainable development are briefly described below:

i. Proper use of natural resources

Human being is the supreme animal among all living beings. Thus, it is the
responsibility of human beings to protect other living beings. Human beings should
be careful while using other living beings and non-living things for their benefit. It
means that the natural resources should not be used haphazardly. People should
not clear the forest for their benefit alone. It is necessary to conserve forest for the
protection of plants and animals. The protection of the forest helps the protection of
natural environment. Similarly, people should not degrade water sources only for
their benefit. We should use minerals, drinking water, forest resources, etc. wisely
and economically. We should reduce the use of chemical fertilizers and insecticides.

The degradation of water resources results in degradation of natural environment.
Ultimately, the degradation of natural environment results in depletion of
animals and plants. The degradation and depletion of environment in the name of
development is opposite to the concept of sustainable development. Sustainable
development helps preserve various types of living beings and non-living things.
The conservation and protection of environmental components is advantageous for
human beings for a long time. The proper use of natural resources is closely related
to sustainable development.

ii. Sustainability of natural resources

Natural resources should be conserved for their sustainability. The major goal of
sustainable development is to conserve various natural resources by conserving
natural environment. Development works should not be carried out by destroying
natural environment. According to the concept of sustainable development, land
is used for farming without destroying its condition. Similarly, water resources
are used for the benefit of human beings along with their conservation. Therefore,
sustainable development emphasizes on the conservation of all kinds of natural
resources.

iii. Maintaining the limited capacity of natural resources

Each natural resource has its limited capacity. In other words, natural resources have
limited bearing capacity. Land has limited capacity and it cannot bear the growth of
unlimited plants. If we plant and grow the plants without caring for the capacity of
the land, the plants cannot grow and develop properly. It also degrades the quality
of the land. Similarly, pasture land has its limited capacity. The grazing of cattle in
excess of the capacity of pasture land degrades the condition of that area. The use
of natural resources beyond their capacity results in adverse effects on the entire
environment. Therefore, sustainable development emphasizes on the utilization
of natural resources by maintaining their limited capacity. It helps conserve and
maintain natural resources for a long time and it also sustains development works.

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iv. Growth of mutual cooperation

Sustainable development is the need of the present world. It is beneficial for all the
people in the world. It utilizes natural resources without their degradation. It stops
the rate of destroying and depleting the quality of natural resources. The international
organizations have their keen interest in sustainable development. Therefore,
international cooperation can be achieved for development works. It promotes good
relation among the countries and peoples of the world. The sustainable development
of each nation results in the sustainable development of the whole world. It helps
conserve the earth and creates sustainable society all over the world.

v. Continuation and improvement of 'human living'

Human beings fulfil their demands by using natural resources from the environment.
Human beings produce food on land and irrigate the farm for agricultural production
with water resources. Timbers and medicinal herbs are found in the forest. Human
beings use various raw materials from the environment for the industrial production.
These activities help human beings continue with their life easily and comfortably.
The fluctuation of natural resources results in difficulty in the lives of human beings.
As a result, human beings cannot continue their life smoothly. But sustainable
development stops fluctuation in natural resources by conserving the natural
environment. Sustainable development helps make lives of human beings easier
and comfortable. It improves the quality of life and makes life pattern sustainable.

vi. 'Capacity growth' of local level

The concept of sustainable development should be implemented into practice. This
concept should be spread in villages as well as in cities. It results in development
and environmental conservation simultaneously. It helps generate awareness
regarding importance of sustainable development. As a result, human beings
start understanding the importance of sustainable development. The passion of
sustainable development of human beings results in their involvement in such
activities. It increases the capacity of human beings for the development in local
level. Ultimately, it also conserves natural environment.

vii. Development of 'conservation spirit'

Environmental conservation is the common duty and responsibility of all human
beings. It is not an individual effort. The involvement of all human beings is
necessary in the campaign of environmental conservation. The concept of sustainable
development and its practical implication should be forwarded. It helps develop the
spirit of conservation among human beings. The development of conservation spirit
is a great achievement for the conservation of natural environment. It protects and
conserves all living beings and non-living things in the environment.

passion / ˈ p æ ʃ n / - a very strong feeling of sth Oasis School Science and Environment - 8 379
ENVIRONMENT SCIENCE

viii. Utility for future generation and long lasting thought

There are limited amount of natural resources in the environment. Human beings
should not use these resources in excess. The conservation and protection of the
natural resources is also necessary along with their use. The concept of sustainable
development helps preserve the present resources for the utility of the future
generations. It will not create difficulty in continuation of life in the future. Sustainable
development helps conserve the natural resources for the future generations with
their proper use at present.

Project work

• Observe any two development activities in your locality. What are the adverse
effects of those activities on environment? Also, find out whether these activities
are being conducted on the concept of sustainable development or not? Prepare
a short report and submit to your science teacher.

Reasonable fact-1

The limit of the development should be determined for sustainable development.
Limit of development limits the use of natural resources like minerals, water resources,
forest resources, etc. and reduces the over use of chemical fertilizers and insecticides. It
also protects private property and enables citizens to have more control over their own
lives which helps in environmental conservation. So, limit of development should be
determined for sustainable development.

Reasonable fact-2

‘Long lasting thought’ is required for sustainable development.
There is limited amount of natural resources in the environment. Human beings
should not use these resources in excess. The conservation and protection of the
natural resources is also necessary along with their use. It will not create difficulty in
continuation of life in future. Sustainable development helps to conserve the natural
resources for the future generations with their proper use at present. So, ‘long lasting
thought’ is required for sustainable development.

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SUMMARy

• The physical and biological world where we live is called environment.

• Environment is the totality of physical, biological, natural, social, economic,
chemical and cultural aspects.

• All activities of human beings have a great impact on the environment.

• All the development works are carried out for the benefit of human beings.
These works promote economic, social and cultural aspects of human beings.
Therefore, it is necessary to use the resources available in the environment
for the benefit of human beings.

• Sustainable development is defined as the development that meets the
needs of the present without compromising the ability of future generations
to meet their own needs.

• Sustainable development is the need of the world. The benefit of sustainable
development can be achieved in local, national and international level.

• Human being is the supreme animal among all living beings. Thus, it is the
responsibility of human beings to protect other living beings.

• The proper use of natural resources is closely related to sustainable
development.

• The major goal of sustainable development is to conserve various natural
resources by conserving natural environment.

• Sustainable development emphasizes on the utilization of natural resources
by maintaining their limited capacity.

• The fluctuation of natural resources results in difficulty in the lives of
human beings.

• Sustainable development is beneficial for all the people in the world. It
utilizes natural resources without their degradation. It stops the rate of
destroying and depleting the quality of natural resources.

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Exercise

1. Choose the best answer from the given alternatives.

a. Biodiversity is the short form of .................................... .

i. ecological diversity ii. biological diversity

iii. ecosystem diversity iv. species diversity

b. Presence of different types of plants and animals on the earth is called ............
........................ .

i. ecosystem diversity ii. genetic diversity

iii. ecological diversity iv. species diversity

c. The hereditary unit that transmits characteristics of parents to their offspring
is called .................................... .

i. gene ii. species

iii. genetics iv. reproduction

d. Which of the following is not the principle of sustainable development?

i. Conservation of biodiversity

ii. Conservation of ecosystem

iii. Pollution control

iv. Population growth

2. Fill in the blanks with appropriate words.
a. ..................... ecosystem includes forest, cropfield, desert, etc.
b. Genetic diversity is the variation in ..................... units.
c. Human activities should be conducted within the ..................... capacity of the
earth.
d. Sustainable development is also called ......................
e. ..................... development emphasizes the conservation of cultural resources.

3. Answer the following questions.
a. What is meant by biodiversity? Write with examples.
b. What is ecosystem diversity? Give one example of species diversity.
c. What is genetic diversity? Give an example.

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d. What are genes? Where are they located?
e. Why should we conserve biodiversity?
f. What is meant by sustainability of natural resources?
g. What is sustainable development?
h. What is meant by carrying capacity of the earth?
4. Differentiate between:
a. Ecosystem diversity and Genetic diversity
b. Species diversity and Genetic diversity
c. Development and Sustainable development
5. Explain the types of biodiversity in brief.
6. Explain the principles of sustainable development in brief.
7. What are global efforts for sustainable development? Describe.
8. Explain the importance of sustainable development.



ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 383

Science and Environment

Basic Level Examination
New Specification Grid

S.N. Area and Units No. of No. of Sub Full (K) (U) (A) (HA) Total

Questions questions Marks 30% 40% 20% 10%

Physics Measurement, Force and

Velocity

Simple Machine, Pressure,

Work, Energy and Power 5 10 25 7.5 10 5 2.5

Heat, Light

Sound, Magnetism,

Electricity

Chemistry Matter

Metal and Non-metal 3 6 15 4.5 6 3 1.5
Acid, Base and Salt

Some Useful Chemicals

Biology Living Beings

Cell and Tissue 3 6 15 4.5 6 3 1.5
Life Process

Geology and Structure of the Earth

Astronomy Weather and Climate 1 2 5 1.5 2 0 15
Earth and Space

Environment Environment and Its

Science Balance

Environmental Degradation

and Its Conservation

Environment and

Sustainable Development

Total 15 30 75 22.5 30 14 8.5

Note:
• There will be total 15 questions and each question has two sub-questions. The weighting

of each main question will be 5 and that of each sub-question will be 2 or 3.

• All units should be included while setting the question paper.

• Question based on knowledge, understanding, ability and higher ability should be
included while making question paper.

K = Knowledge, U = Understanding, A = Ability, HA = Higher Ability

384 Oasis School Science and Environment - 8 ENVIRONMENT SCIENCE

New Model Question

Science and Environment

Class : 8 Full marks : 75
Time 2 hrs. 15 mins.

Attempt all the questions.

Group-A

1. (a) What is mass? Write two differences between fundamental and derived

unit. 1K + 2U

(b) What will be the final velocity of vehicle, if it started from rest and accelerates

at 4m/s2 after 5 second? 2HA (Ans: 20 m/s)

2. (a) Define: 1+1+1=3K

i) Mechanical advantage

ii) Velocity ratio

iii) Efficiency

(b) Prove that, liquid pressure (P) = hdg 2HA

3. (a) Define work and power, write the relationship between them. 1K+1K+1U

(b) Write two differences between clinical and simple thermometer. 2U

4. (a) What is refraction of light? Which type of mirror is used as side mirrors in ve-

hicles and why? 1K+0.5K+1A

(b) What is unit of frequency? Write any two differences between echo and rever-

beration. 0.5K + 2U

5. (a) Draw the diagram to show the arrangement of the molecular magnets in a

magnet and magnetic substance. 2A

(b) Why we use dry cell in torch light? Write any three reasons. 3A

Group-B

6. (a) Write the molecular formula of salt. 1k+2U

Write the word equation of the following chemical equation.

Hydrogen + Oxygen → Water

(b) Draw the electronic configuration of Magnesium atom.

7. (a) What is chromatography? Which types of the mixtures are separated from
it? 1K+2U

(b) Write any one use of sulphur and copper each. 1+1=2U

8. (a) What effect do acid, base and salt have on different indicator? Show in a table.
3A

ENVIRONMENT SCIENCE Oasis School Science and Environment - 8 385

(b) How can you detect hardness of water collected from different sources? 2U

Group-C

9. (a) Draw a labelled diagram of virus.

(b) Why does modification of root occur? Write any two causes or uses. 2U

10. (a) Write the relationship between cells, tissues and organs in human body. 3U

(b) Write the name of tissues found in animals. 2K

11. (a) What do you mean by vegetative propagation? Write the name of two plants

which is reproduced by this process. 1K+1U

(b) What is photosynthesis? How can you demonstrate that plant prepares their

food on its leaves? Write with an experiment. 1K+2HA

Group-D

12. (a) What is soil erosion? Which region of Nepal does rain fall more? Why?
1K+1.5U

(b) What is phases of moon? Write any three reasons for the existence of living

beings on the earth. 1K+1.5U

Group-E

13. (a) What can human being get from nature? Write any three examples. 3U

(b) Write the difference between national park and wildlife reserve. 2K

14. (a) Write any four reasons of water pollution. Give any one measure that mitigates

for minimizing water pollution in your region. 2U+1HA

(b) What is climate change? Write two effects of climate change. 1+1=2k+A

15. (a) What is Bio-diversity? Write its types. 1.5+1.5=3K

(b) What can you do in your residential area for protection of environment? Write

any four points. 2

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