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INTRODUCTION TO ENVIORNMENTAL STUDIES:

Multi-disciplinary nature of environmental studies

An environmental study is a ‘multi-disciplinary academic field which systematically studies human

interaction with its environment. Environmental studies have a broader canvas. It includes not only
the study of physical, chemical and biological characters of the environment but also social,
economic, cultural and even political aspects of the environment which makes it a very dynamic
academic field.

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 COMPONANTS OF ENVIORNMENTAL

1. Atmosphere: Generally found in gages

2. Lithosphere: Generally found in rocks

3. Hydrosphere: Generally found in water

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Atmosphere:

It is the air blanket which surrounds the planet and upheld by the gravity of that planet. The atmosphere
of earth has highest density as it is composed of different gases. The most abundant gas in the
atmosphere is nitrogen, with oxygen second. Argon, an inert gas, is the third most abundant gas in the
atmosphere. The atmosphere is composed of a mix of several different gases in differing amounts. The
permanent gases whose percentages do not change from day to day are nitrogen, oxygen and argon.
Nitrogen accounts for 78% of the atmosphere, oxygen 21% and argon 0.9%. Gases like carbon dioxide,
nitrous oxides, methane, and ozone are trace gases that account for about a tenth of one percent of the
atmosphere. Water vapor is unique in that its concentration varies from 0-4% of the atmosphere
depending on where you are and what time of the day it is. In the cold, dry artic regions water vapor
usually accounts for less than 1% of the atmosphere, while in humid, tropical regions water vapor can
account for almost 4% of the atmosphere. Water vapor content is very important in predicting weather.

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The atmosphere is comprised of layers based on temperature. These layers are the troposphere,
stratosphere, mesosphere and thermosphere. A further region at about 500 km above the Earth's
surface is called the exosphere.

Troposphere

This is the lowest part of the atmosphere - the part we live in. It contains most of our weather - clouds,
rain, snow etc. In this part of the atmosphere the temperature gets colder as the distance above the
earth increases, by about 6.5°C per kilometre. The actual change of temperature with height varies
from day to day, depending on the weather. The troposphere contains about 75% of all of the air in the
atmosphere, and almost all of the water vapour (which forms clouds and rain). The decrease in
temperature with height is a result of the decreasing pressure. The top of the troposphere is called the
tropopause. This is lowest at the poles, where it is about 7 - 10 km above the Earth's surface. It is
highest (about 17 - 18 km) near the equator.

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Lithosphere
Lithosphere is the rigid, rocky outer
layer of the Earth, consisting of the
crust and the solid outermost layer
of the upper mantle. It extends to a
depth of about 60 miles (100 km). It
is broken into about a dozen
separate, rigid blocks, or plates (see
plate tectonics). Slow convection
currents deep within the mantle,
generated by radioactive heating of
the interior, are believed to cause
the lateral movements of the plates
(and the continents that rest on top
of them) at a rate of several inches
per year. There are two types of
lithosphere: Oceanic lithosphere-
which is associated with oceanic
crust and exists in the ocean basins.
Continental lithosphere- which is
associated with continental crust.
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Hydrosphere

A hydrosphere is the total amount of

water on a planet. The hydrosphere
includes water that is on the surface
of the planet, underground, and in the
air. Water is a basic necessity of life.
Since 2/3 of the Earth is covered by
water, the Earth is also called the blue
planet and the watery planet.[notes 1]
The hydrosphere plays an important
role in the existence of the
atmosphere in its present form.
Oceans are important in this regard.
When the Earth was formed it had
only a very thin atmosphere rich in
hydrogen and helium similar to the
present atmosphere of Mercury.

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Biosphere

The biosphere is made up of the parts of

Earth where life exists. The biosphere
extends from the deepest root systems of
trees to the dark environment of ocean
trenches, to lush rain forests and high
mountaintops. Biosphere is relatively thin
life-supporting stratum of Earth’s surface,
extending from a few kilometres into the
atmosphere to the deep-sea vents of the
ocean. The biosphere is a global ecosystem
composed of living organisms (biota) and
the abiotic (nonliving) factors from which
they derive energy and nutrients.
Biosphere is the universal sum of total
ecosystem or the zone of life for plants,
animals and microbes on the Earth's crust
controlled by natural self-regulating
system.

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 Sustainable Development: History and Concepts
Sustainable development: the needs of the present without compromising the ability of
future generations to meet their own needs. It contains within it two key concepts:
the concept of 'needs', in particular the essential needs of the world's poor, to which
overriding priority should be given.
the idea of limitations imposed by the state of technology and social organization on the
environment's ability to meet present and future needs

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 Ecosystem

The ecosystem term was first coined by an

ecologist Arthur Tansley in 1935. The
ecosystem is a balance or equilibrium between
living and non-living factors of the ecosystem
where they tend to interact with each other. All
living things, including plants, animals, and
microorganisms, depend on non-living
substances to survive and maintain the
equilibrium of the natural environment.

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 What is an Ecosystem?

An ecosystem can be defined as the biological community of living beings, communicating

with their environment and other non-living components. Every living thing, including man,
is involved in these complex networks of interdependent relationships, which are called
ecosystems.

Structure of the Ecosystem:

The structure of an ecosystem is defined by the association of both biotic and abiotic
components of the ecosystem. This encompasses the percentage of energy in our
environment. The structure of an ecosystem can be divided into two main elements, namely:
biotic and abiotic components. Let’s learn about these in detail.

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 Biotic Components

Plants, animals, microorganisms, aquatic plants, and all other living creatures are the biotic
components of the ecosystem. These biotic components can be classified into:
Producers: All autotrophs like plants, phytoplankton, etc. that can produce their food using sources
like sun, water, carbon dioxide, or any other chemical elements belong to this category.

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Consumers: All heterotrophs, primarily animals, that are dependent on the producers or other
organisms are called consumers. These consumers many types
Primary consumers: All herbivores that directly depend on plants, such as cows, goats, rabbits, and
sheep, are considered primary consumers.
Secondary consumers: All that depend on primary consumers for food are considered secondary
consumers. The secondary consumer can be omnivores or carnivores.
Tertiary consumers: All animals that depend on secondary-level organisms for their food are known
as tertiary consumers.
Quaternary consumer: Those animals that depend on the tertiary level organism for their food and
are known as the quaternary consumer. This level is present in some food chains only.

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Decomposers: All microorganisms, such as bacteria and fungi, that depend on decaying and dead
matter for food fall under this category. It contributes to environmental cleanup and ecosystem
nutrient recycling. These nutrients support plant development and subsequently ecosystem
maintenance.

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 Abiotic Components

Abiotic components are chemical or/and physical factors that perform on the living components at any
time of their life. These are known as ecological factors. The chemical and physical factors are features of
an environment. Nutrients, soil, air, and light, etc. form these abiotic factors of the ecosystem.
The abiotic components change from one ecosystem to another ecosystem. The abiotic components may
contain dissolved oxygen, available nutrients salinity, water depth, turbidity, sunlight, and water pH.
Similarly, abiotic components in various terrestrial ecosystems may contain sunlight, nutrients, wind,
altitude, rain, temperature, soil types, soil, etc.

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Edaphic factors: This term arises through the
Greek term 'edaphos' that means floor.
Edaphic factors contain substratum and soil. It
indicates the abiotic components such as land
geography and soil features like mineral
content. The land topography such as slopes,
depressions, valleys, mountains, and
elevations each contribute to the features of
the ecosystem. Similarly, soil features such as
density, structure, texture, and composition
negotiate which plants could grow, and what
creatures could live there.
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Topographic factors: Topographic factors
contain altitude, surface exposure, and slope, etc.
These factors define how the activity of the
human can affect the resources and land in the
area. All humans include affecting on several
ecosystem features. Topographic components are
likely to lead to large-scale modifications. Thus,
they could include profound impacts on various
other biotic factors, abiotic factors, the whole
ecosystem, and whole biomes. Some of the
examples include farming, dam building, mining,
and forest clear-cutting.

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Climatic factors: Climatic factors
contain precipitation, light,
temperature, atmospheric wind, and
humidity. The wind can spread seeds
in the air that helps with
implantation and provides plants an
opportunity to grow. Also, the wind
is an important illustration of abiotic
components such as wind speed and
direction that can impact humidity.

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 Functions of an Ecosystem

The functions of the ecosystem are as follows:

It regulates the essential ecological processes, supports life systems and renders stability.
It is also responsible for the cycling of nutrients between biotic and abiotic components.
It maintains a balance among the various trophic levels in the ecosystem.
It cycles the minerals through the biosphere.
The abiotic components help in the synthesis of organic components that involve the exchange of
energy.

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So the functional units of an ecosystem or functional components that work together in an
ecosystem are:
•Productivity – It refers to the rate of biomass production.
•Energy flow – It is the sequential process through which energy flows from one trophic level to
another. The energy captured from the sun flows from producers to consumers and then to
decomposers and finally back to the environment.
•Decomposition – It is the process of breakdown of dead organic material. The top-soil is the
major site for decomposition.
•Nutrient cycling – In an ecosystem nutrients are consumed and recycled back in various forms
for the utilization by various organisms.

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 What is a Food Chain?

A food chain refers to the order of events in an ecosystem, where one living organism eats another
organism, and later that organism is consumed by another larger organism. The flow of nutrients and
energy from one organism to another at different trophic levels forms a food chain.
The food chain consists of four major parts, namely:
The Sun: The sun is the initial source of energy, which provides energy for everything on the planet.
Producers: The producers in a food chain include all autotrophs such as phytoplankton, cyanobacteria,
algae, and green plants. This is the first stage in a food chain. The producers make up the first level of a
food chain. The producers utilise the energy from the sun to make food. Producers are also known as
autotrophs as they make their own food. Producers are any plant or other organisms that produce their
own nutrients through photosynthesis.

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•Consumers: Consumers are all organisms that are dependent on plants or other organisms
for food. This is the largest part of a food web, as it contains almost all living organisms. It
includes herbivores which are animals that eat plants, carnivores which are animals that eat
other animals, parasites that live on other organisms by harming them and lastly the
scavengers, which are animals that eat dead animals’ carcasses.
Here, herbivores are known as primary consumers and carnivores are secondary
consumers. The second trophic level includes organisms that eat producers. Therefore,
primary consumers or herbivores are organisms in the second trophic level.
•Decomposers: Decomposers are organisms that get energy from dead or waste organic
material. This is the last stage in a food chain. Decomposers are an integral part of a food
chain, as they convert organic waste materials into inorganic materials, which enriches the
soil or land with nutrients.
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 What is a Food Web?

Several interconnected food chains form a food web. A food web is similar to a food chain but the
food web is comparatively larger than a food chain. Occasionally, a single organism is consumed by
many predators or it consumes several other organisms. Due to this, many trophic levels get
interconnected. The food chain fails to showcase the flow of energy in the right way. But, the food
web is able to show the proper representation of energy flow, as it displays the interactions between
different organisms.

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 Ecological succession

“Ecological succession is a series of changes that occur in an ecological community over time.”

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 Types of Ecological Succession

Primary Succession: Primary succession is the succession that starts in lifeless areas such as the
regions devoid of soil or the areas where the soil is unable to sustain life.
When the planet was first formed there was no soil on earth. The earth was only made up of rocks.
These rocks were broken down by microorganisms and eroded to form soil. The soil then becomes the
foundation of plant life. These plants help in the survival of different animals and progress from primary
succession to the climax community. If this primary ecosystem is destroyed, secondary succession
takes place.

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Secondary Succession
Secondary succession occurs when the primary ecosystem gets destroyed. For eg., a climax community gets
destroyed by fire. It gets recolonized after the destruction. This is known as secondary ecological succession.
Small plants emerge first, followed by larger plants. The tall trees block the sunlight and change the structure
of the organisms below the canopy. Finally, the climax community arrives.

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 Biogeochemical (Nutrient cycling) process

“Biogeochemical cycles mainly refer to the movement of

nutrients and other elements between biotic and abiotic
factors.”

The term biogeochemical is derived

from “bio” meaning biosphere, “geo” meaning the geological
components and “chemical” meaning the elements that move
through a cycle.

The earth obtains energy from the sun which is radiated back as
heat, rest all other elements are present in a closed system. The
major elements include:
•Carbon
•Hydrogen
•Nitrogen
•Oxygen
•Phosphorus
•Sulphur

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 Importance of Biogeochemical Cycles

These cycles demonstrate the way in which the energy is used. Through the ecosystem, these cycles
move the essential elements for life to sustain. They are vital as they recycle elements and store them
too, and regulate the vital elements through the physical facets. These cycles depict the association
between living and non-living things in the ecosystems and enable the continuous survival of
ecosystems.
It is important to comprehend these cycles to learn their effect on living entities. Some activities of
humans disturb a few of these natural cycles and thereby affecting related ecosystems. A closer look at
these mechanisms can help us restrict and stop their dangerous impact.

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