Environment
The sum total of all surroundings of a living organism,
including natural
forces and other living
things, which provide conditions for development and growth as well as of danger and damage. A person’s environment is made up of everything that
surrounds him or her. It encompasses all living and non-living
things occurring naturally
on Earth or some region
thereof.
At
the very fundamental level, the planet Earth is our environment.
Major components of the environment
The environment may broadly be considered to
comprise the following five segments:
(1) Lithosphere, (2) Hydrosphere, (3) Atmosphere,
(4) Biosphere, and (5) Anthrosphere.
Lithosphere
The
Lithosphere, or solid Earth, is that
part of the Earth upon which humans live and from which they extract most of
their food, minerals, and fuels.
The most important part of the lithosphere
for life on Earth is soil formed by the disintegrating weathering action of
physical, geochemical, and biological processes on rocks. It is the medium upon which all plants grow,
and virtually all terrestrial organisms depend upon it for their existence. Good soil – and a climate
conducive to its productivity – is the most valuable asset a nation can have. The
productivity of soil is strongly affected by environmental conditions and
pollutants.
Hydrosphere
The
hydrosphere contains Earth’s water.
It is a vitally important substance and occurs in all parts of the environment.
A
fragile resource—water is perhaps
the most fundamental of the resources we require. It is
unquestionably the lifeblood of the
Earth—no animal or plant life would exist without it. Water is essential part of all living systems
and is the medium from which life evolved and in which life exists. Energy and
matter are carried through various sphere of the environment by water.
Water covers about 70% of Earth’s surface.
So the total amount of water on our planet is immense—more than 1.4 billion km3. If the Earth had a
perfectly smooth surface, an ocean about 3
km deep would cover everything.
Over 97% of Earth’s water is in oceans and most of the remaining
fresh water is in the form of ice.
·
All water
(100%): Oceans and saline lakes =
97.5%;
·
Fresh
water = 2.5%
Ice caps and glaciers
= 1.97%;
Groundwater = 0.5%;
Other water (lakes,
rivers, soil moisture, atmosphere, etc)
= 0.03%.
Thus, not even 1% of the total world’s
water resources is available for
exploitation by man for
domestic, agricultural and industrial purposes. It is a critical, limited,
renewable resource in many regions on Earth.
Atmosphere
The
atmosphere is the thin layer of gases that envelopes earth is a great resource to all living things on
the planet. It is composed of gas molecules held close to Earth’s surface by a
balance between gravitation and thermal movement of air molecules. It is the source of carbon dioxide for plant photosynthesis
and of oxygen for respiration. It
provides the nitrogen that
nitrogen-fixing bacteria and ammonia-manufacturing industrial plants use to
produce chemically-bound nitrogen. As a
basic part of the hydrologic cycle, the
atmosphere transports water from the oceans to land. The atmosphere
serves a vital protective function, absorbing harmful ultraviolet (UV)
radiation from the sun and stabilizing Earth’s temperature.
The
atmosphere is a dynamic system,
changing continuously. Many complex chemical reactions take place in the
atmosphere; changing from day to night and with chemical elements available.
Biosphere
Biosphere
is the life zone of the earth, including the lower part of the atmosphere, the
hydrosphere, soil, and the lithosphere to a depth of about 2 kilometers. The biosphere
covers the entire realm of living organisms and their interactions with other
segments of the environment, namely lithosphere, atmosphere, and hydrosphere.
The
biosphere strongly influences, and is strongly influenced by the other parts of
the environment. Ecosphere is the regions of the universe, especially
on the earth, that are capable of supporting life; the biosphere.
Anthrosphere
The
anthrosphere may be defined as that part of the environment made or modified by
humans and used for their activities.
The
anthrosphere consists of a number of different parts. These may be categorized
by considering where humans live; how they move; how they make or provide the
things or services they need or they want; how they produce food, fiber and
wood; how they obtain, distribute, and use energy; how they communicate; how
they extract and process nonrenewable minerals; how they collect, treat and
dispose of wastes. It is obvious that the anthrosphere is very complex with an
enormous potential to affect the environment.
