01_ Introduction to Environmental Science (Video Lecture) Video Lecture - Class 9

Friends what comes to your mind when you hear
the word
environment?
The simplest thing which one can say about
our environment is our
surrounding.
Here let us just assume that we are all sitting
in a park.
Anything and everything we can see in this
park are all part of our
environment.
now let us just list down few things that
we see here in this
park:
- People sitting or walking around.
- Children playing
- The lush green grasses, plants, trees.
- The tiny insects, birds .
Benches
Swings
- Play ground
- Slide
? These are few objects which are placed near
or around us and they
are all part of our surrounding.
Our surrounding can also be like
? Your locality like some place where the
park is located.
? Our country
? On a broader term planet earth itself
Now that We have already listed the things
we see in the park.
If we
observe, the things
to our left all have something in common i.e
they have LIFE in them or
they perform various LIFE PROCESSES like eating,
breathing,
reproduction.
So we call them all as living organisms; which
in other terms are called
as BIOTIC COMPONENT.
BIOTIC because Bios mean life.
And , the things we listed down to our right
does not have life in them,
so we call them as nonliving organisms or
the ABIOTIC
COMPONENT.
ABIOTIC because it has no life.
Since now we know what our environment consists
of we can easily define
what Environmental Science is�
Learning about Environmental Science actually
means :
? To understand how nature works.
? To understand the various interactions of
different components of our
environment.
? Also to find how we Humans affect our environment.
To understand it further,
Here we shall look at how plants grow?
plants take in carbon dioxide CO2 from the
AIR, WATER from the SOIL
and SUNLIGHT to make their food through chemical
process and the
process is known as photosynthesis and further
the plants also serve as
food for higher animals.
Now imagine if these plants were in isolation,
i.e without sunlight, carbon
dioxide, water, soil.. will the process of
photosynthesis be complete or
will the plant be able to serve as food for
higher animals????????
The answer is NO �
Also if you consider the example of humans�
will we be able to survive
without air water and food??????
The answer is again NO�
So we can say all the BIOTIC components constantly
interact or
exchange things with each other as well as
the ABIOTIC components for
their survival or existence.
the plants are just a small aspect of our
environment but if we consider a
much larger or broader aspect like our planet
earth lets see how the
various components work on a broader scale?
Iam sure that you all have seen the picture
of our planet EARTH.
Although it looks like one large structure,
it has many different features.
If we take the entire land surface on the
earth and club it together we get a
separate sphere called lithosphere.
Similarly The air surrounding our earth surface
can be taken as one sphere called
atmosphere
The bluish part on our globe which indicates
the water surfaces would form
another sphere are called hydrosphere.
And also The various life forms on the earth
like plants, animals, microorganisms
and we humans are all part of another sphere
called biosphere.
When these four spheres combine it gives us
the entire large sphere which is our planet
earth.
From these four spheres itself man gets all
useful things that satisfy many of
his day to day requirements.
like the lithosphere which is the land component
is useful to man for carrying
out agricultural activities, constructing
houses, we get many useful minerals
from the soil.
Similarly hydrosphere provides us with water
in different forms which we use
for drinking, washing, cleaning, for agriculture,
for industries etc.
The air which we breathe, sunlight, weather,
wind etc are obtained from the
atmosphere.
The food which we eat, fire wood from the
forests are obtained from the
biosphere.
All these things are obtained from our nature
and are very much useful to us.
And hence we call it all as NATURAL RESOURCES.
Here if you split the
term the meaning is very simple.
Natural means from nature and resource
means something which is of use to us.
But for satisfying his increasing demands
man is continuously using these
resources and hence they are depleting at
a much faster rate.
Our planet
earth has its own way to replenish many of
these resources i.e earth can get
back many of these resources into existence.
But this replenishing rate is slow
as compared to the speed in which it is getting
consumed.
so various activities which man does affects
the balance between the four
spheres (atmosphere, lithosphere, hydrosphere,
biosphere)..
Like forest is an
important resource and we are cutting them
down for land and for the various
forest products.
And when the forest cover is destroyed it
would affect rainfall
which in turn will affect agricultural production.
So when in this way balance is disturbed it
directly or indirectly affects all living
and non living components.
And some these consequences arising out of
man�s activities are what we hear in our
present day life like pollution, global
warming, ozone depletion, climate change.
we also hear about natural
disasters like the very recent incidence of
earthquake and tsunami in Japan,
A very severe cyclonic storm�Hudhud�hit
the states of
Andhra�Pradesh�and�Odisha in India,
powerful Typhoon Hagupit that hit
central Philippines what does all these indicate?
Is it the mother earth who�s
changed or is it we humans?
Here we ,must think on what our mother earth
is providing us and what are we
giving her in return
Friends, the four spheres which we learnt
just nw are the basis of all
environmental processes.
And they all have unique properties which
we will
know in details in our coming sessions.
I hope you liked this session
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till we meet the next time keep watching keep
learning.
Thank you.