CHAPTER 2: ENVIRONMENT AND ENVIRONMENTAL PROBLEMS
SECTION 1: DETAILED REVISION NOTES
1. Concept and Definition of Environment
- Etymology: The
word "environment" is derived from the French word "environ," meaning "to encircle" or "surroundings."
- General Definition: Environment refers to the total system of physical,
chemical, biological, and social conditions surrounding an organism or a
community of organisms.
- Erich Zimmermann’s Definition: According to economic geographer Erich Zimmermann, environment
is the sum total of all external forces, influences, and conditions that
affect the life, nature, behaviour, growth, and development of living
organisms.
2. The Four Spheres of the Earth's Environment
The
Earth’s natural environment is composed of four interconnected and interacting
spheres:
┌────────────────────────┐
│ ATMOSPHERE │
│ (Gaseous Envelope) │
└───────────┬────────────┘
│
┌────────────────────────┼────────────────────────┐
│ │ │
┌────┴───────────────────┐ │
┌───────────────────┴────┐
│
LITHOSPHERE │ ◄──┼──► │ HYDROSPHERE │
│ (Solid
Earth/Crust) │ │
│ (Water Bodies/Seas) │
└────┬───────────────────┘ │
└───────────────────┬────┘
│ ▼ │
└────────────────► BIOSPHERE ◄──────────────────┘
(Realm of Living Life)
- Lithosphere (Solid Earth):
- Covers approximately 29%
of the Earth's total surface.
- Consists of rocks,
minerals, soil, continents, mountains, plateaus, and plains.
- Provides land for human
settlement, agriculture, and mineral resources.
- Hydrosphere (Water Sphere):
- Covers approximately 71%
of the Earth's total surface.
- Includes oceans, seas,
rivers, lakes, glaciers, polar ice caps, and underground water.
- 97% of the hydrosphere is salty ocean water; only 3%
is fresh water.
- Atmosphere (Gaseous Blanket):
- Extends up to about 10,000
km above the Earth’s surface, though most gas mass is within the
lower 32 km.
- Main gases: Nitrogen (78.08%), Oxygen (20.95%), Argon (0.93%), Carbon
Dioxide (0.036%), water vapour, and trace gases.
- Protects life by
absorbing harmful ultraviolet (UV) solar rays and regulating temperature.
- Biosphere (Zone of Life):
- The narrow interaction
zone where the lithosphere, hydrosphere, and atmosphere meet to support life.
- Includes all living
organisms—plants, animals, microorganisms, and humans.
- Extends from deep ocean
trenches to mountain peaks.
3. Classification of Environment
- Natural (Physical) Environment:
- Created purely by nature
without human modification.
- Divided into:
- Abiotic
(Non-living): Land, water, air,
light, temperature, rocks, soil.
- Biotic
(Living): Plants, animals,
microorganisms.
- Man-Made (Human / Social) Environment:
- Created or altered by
human intellect, labour, science, and technology.
- Includes houses, cities,
transport networks, dams, industries, socio-economic institutions, laws,
culture, and traditions.
4. Environmental Problems and Their Geographical Classification
An environmental
problem arises when the natural balance between living organisms and their
non-living environment is disrupted by natural disasters or excessive,
unscientific human activities.
Classification by Geographical Extent:
|
Spatial Level |
Definition |
Examples |
|
Local Level |
Confined to a small, localised area or specific
community. |
• Bank
erosion of the Brahmaputra River in a specific village.
•
Dumping of municipal solid waste in a locality.
• Noise
pollution from a local market or mill. |
|
Regional
Level |
Spreads across a state, large region, or country. |
•
Annual flood and riverbank erosion across the state of Assam.
• Acid
rain in heavy industrial belts.
•
Interstate river water pollution. |
|
Global
Level |
Affects the entire planet and impacts all living
organisms worldwide. |
• Global
Warming & Climate Change
• Ozone
layer depletion
•
Sea-level rise |
5. Major Global & Regional Environmental Issues
A. Environmental Pollution
Pollution
is the undesirable change in the physical, chemical, or biological
characteristics of air, water, or land that adversely affects human life,
wildlife, and natural resources.
- Air Pollution:
- Major Causes: Burning of fossil fuels (coal, petrol, diesel),
industrial toxic emissions, deforestation, and forest
fires.
- Major Effects: Respiratory illnesses (asthma, bronchitis), acid
rain, smog formation, acceleration of the greenhouse effect.
- Water Pollution:
- Major Causes: Industrial effluents, untreated domestic sewage,
agricultural runoff containing chemical pesticides/fertilizers, and oil
spills in oceans.
- Major Effects: Spread of waterborne diseases (cholera, dysentery,
typhoid), loss of marine life, and eutrophication (excessive algae growth that depletes oxygen in water bodies).
- Land / Soil Pollution:
- Major Causes: Non-biodegradable plastics, excessive use of
chemical fertilizers/pesticides, and dumping of electronic and industrial
solid waste.
- Major Effects: Loss of soil fertility, loss of earthworms and
beneficial soil organisms, contamination of groundwater.
- Definition: The
process of land degradation in dry, arid, and semi-arid regions resulting
from natural climatic variations and unsustainable human activities,
turning fertile land into desert-like barren ground.
- Causes:
Overgrazing, deforestation, over-cultivation, and poor irrigation practices
leading to soil salinity.
C. Global Warming & Climate Change
- Greenhouse Effect: The natural process by which greenhouse gases trap
heat radiated from the Earth's surface, keeping the planet warm enough to
support life.
- Global Warming: The excessive, unnatural increase in the Earth’s
average surface temperature due to high concentrations of greenhouse gases
caused by human activities.
- Primary Greenhouse Gases:
- Carbon Dioxide—Major contributor (fossil fuel burning,
deforestation).
- Methane—Released from paddy fields, livestock, and waste
dumps.
- Nitrous Oxide—From agricultural fertilisers and chemical
industries.
- Chlorofluorocarbons—Reeds from refrigeration, air conditioning, and
spray propellants.
SECTION 2: ASSEB HSLC EXAM PATTERN QUESTION BANK
GROUP A: VERY SHORT ANSWER QUESTIONS (1 Mark Each)
Q1. Who
defined environment as "the sum total of all external forces, influences,
and conditions which affect the life, nature, behaviour, growth, and development
of living organisms"?
Answer: Erich Zimmermann.
Q2. What
is the ratio of land and water on the surface of the Earth?
Answer: Land covers approximately 29%, and water covers 71% of the
Earth's surface area.
Q3. Name
the narrow zone where life exists on Earth.
Answer: Biosphere.
Q4. Give
two examples of a local environmental problem.
Answer:
- Soil erosion in a specific agricultural plot.
- Water pollution in a village pond due to
domestic sewage.
Q5.
Mention two major greenhouse gases responsible for Global Warming.
Answer: Carbon Dioxide and Methane.
Q6. Name
the main gas present in the Earth’s atmosphere by volume percentage.
Answer: Nitrogen gas (78.08%).
Q7. Give
an example of a regional environmental problem in Assam.
Answer: The annual flood and riverbank erosion problem along the Brahmaputra and
Barak river valleys.
GROUP B: SHORT ANSWER QUESTIONS (2 or 3 Marks Each)
Q8.
Distinguish between Natural Environment and Man-made Environment.
Answer:
|
Parameter |
Natural Environment |
Man-Made Environment |
|
Definition |
The environment is created entirely by natural
forces without human intervention. |
The environment is created or modified by human
technology, skill, and culture. |
|
Components |
Landforms, water bodies, atmosphere, natural vegetation, and wildlife. |
Buildings, roads, bridges, dams, factories, and urban
settlements. |
|
Governing Laws |
Governed by natural ecological laws and physical
cycles. |
Maintained and regulated by human social and
technological systems. |
Q9. Write
a brief note on the Lithosphere and its importance to human life.
Answer: The Lithosphere is the solid outer crust of the Earth consisting of
rocks, soil, and landforms (mountains, plateaus, and plains).
- Importance:
- It provides the topsoil
necessary for crop cultivation and forestry.
- It contains essential
mineral and energy resources (coal, iron, and petroleum).
- It offers land space for
human settlements, transport infrastructure, and industrial setups.
Q10.
Explain the three spatial levels of environmental problems with suitable
examples.
Answer: Environmental problems are categorised into three levels based on
geographical extent:
- Local Level:
Problems restricted to a small area or community.
- Example: Noise pollution caused by a local factory or
localised soil degradation.
- Regional Level: Problems affecting a whole state, region, or river
basin.
- Example: The severe riverbank erosion caused by the
Brahmaputra River in Assam.
- Global Level: Problems impacting the whole Earth regardless of
national boundaries.
- Example: Global warming and depletion of the stratospheric
ozone layer.
Q11. What
is desertification? Mention two major human causes of desertification.
Answer: Desertification is the land degradation process in arid, semi-arid,
and dry sub-humid areas resulting from climatic variations and destructive
human practices, converting fertile land into desert.
- Two Major Human Causes:
- Deforestation: Cutting down forests leaves the topsoil exposed to
wind and water erosion.
- Overgrazing: Excessive livestock grazing removes vegetative
cover, leading to soil compaction and desert-like conditions.
GROUP C: LONG ANSWER QUESTIONS (4 or 5 Marks Each)
Q12.
Discuss the four major spheres of the Earth's environment and explain how they
are interconnected.
Answer: The Earth's environment consists of four interconnected spheres:
- Lithosphere: The
solid crust of the Earth made of rocks and soil. It covers about 29%
of the Earth’s surface and provides land for habitats and agriculture.
- Hydrosphere: The
water realm covering nearly 71% of the Earth's surface, including
oceans, rivers, lakes, and glaciers, essential for liquid life support.
- Atmosphere: The
multi-layered gaseous envelope extending up to 10,000 km that supplies
vital gases and regulates Earth's thermal balance.
- Biosphere: The
life-bearing realm where the lithosphere, hydrosphere, and atmosphere
intersect to sustain living organisms.
Interconnectedness:
None of
these spheres operates independently. For example:
- Plants in the Biosphere take nutrients
from the soil (Lithosphere), absorb groundwater (Hydrosphere),
and take in carbon dioxide from the air (Atmosphere) during
photosynthesis.
- Evaporation from water bodies (Hydrosphere)
enters the air (Atmosphere), condenses to form rain, falls onto
land (Lithosphere), and fuels plant growth (Biosphere).
A severe disturbance in any one sphere (e.g., air pollution in the
atmosphere) directly affects all other spheres.
Q13. What
is Global Warming? Explain four major consequences of Global Warming on the
planet.
Answer: Global Warming refers to the continuous, long-term rise in the
average surface temperature of the Earth caused by the accumulation of
anthropogenic greenhouse gases in the atmosphere.
Four
Major Consequences:
- Melting of Polar Glaciers & Sea-Level
Rise: Higher global temperatures accelerate the
melting of glaciers in Greenland and Antarctica. This causes ocean levels
to rise, threatening coastal cities and low-lying island nations with
permanent submergence.
- Shift in Weather & Climate Patterns: Global warming causes extreme and erratic weather
events such as unseasonal rainfall, severe droughts, destructive cyclones,
and prolonged heatwaves.
- Impact on Biodiversity & Ecosystems: Rapid temperature shifts disrupt forest ecosystems
and marine environments (e.g., coral bleaching). Many species unable to
adapt quickly face extinction.
- Adverse Effects on Agriculture: Unpredictable rainfall cycles, soil drying, and
changing temperature regimes lead to crop failures, reducing global food
security.
Q14.
Write short notes on the following environmental problems with reference to
Assam:
(a)
Riverbank Erosion
(b)
Annual Floods
Answer:
(a)
Riverbank Erosion in Assam:
- Riverbank erosion is a major regional
environmental problem in Assam, primarily caused by the dynamic flow
of the Brahmaputra and Barak rivers and their tributaries.
- Heavy monsoon rainfall leads to strong water
currents that wash away thousands of hectares of fertile agricultural
land, homesteads, and villages every year.
- It causes economic loss, renders thousands of
rural families homeless, and creates socio-economic instability in the
state.
(b)
Annual Floods in Assam:
- Flooding is a recurring natural calamity
occurring during the monsoon season in Assam.
- Factors like intense monsoon rains, steep
topography of surrounding hills, deforestation in catchment areas, and
heavy siltation of riverbeds reduce the water-holding capacity of the
rivers.
- Floods damage standing crops, disrupt
transport systems, cause waterborne disease outbreaks, and lead to heavy
loss of human and animal lives (including wild animals in Kaziranga and
Manas National Parks).
EXAM REVISION CHECKLIST
Before
your exam, make sure you can:
- [x] Draw a labelled diagram showing the
interaction of the 4 spheres.
- [x] Define Environment as given by
Zimmermann.
- [x] Differentiate between Local, Regional,
and Global environmental problems with clear examples.
- [x] List the primary sources and effects of
Air, Water, and Soil pollution.
- [x] Explain the mechanism of the Greenhouse
Effect and Global Warming.
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