❖ All the external factors that affect an organism could be defined as
environment. These factors may be other living organisms or nonliving
variables, such as water, soil, climate, light, and oxygen.
❖ The environment is never static. Physical forces continuously change the
surface of the earth through weather, the action of waves and natural
phenomena such as volcanoes. At the same time they introduce gases, vapor
and dust into the atmosphere.
❖ Living organisms also play a dynamic role through respiration, excretion and
ultimately death and decay, recycling their constituent elements through the
❖ As physical substances are divided into solids, liquids and gases, for
convenience our physical environment can be divided into the atmosphere,
the geosphere, the hydrosphere, the biosphere, the anthroposphere.
3. Environmental Chemistry:
❖ Environmental Chemistry is the science related to the study of various
chemical processes occurring in the environment and includes the study of
various sources and the adverse effects of chemical species and/or substances
formed either by the natural sources or by human activity or alternative on
air, water and soil environment.
❖ “study of chemical processes taking place in the environment or in
❖ Environmental Segments: The environment consists of four segments including
Atmosphere, hydrosphere, lithosphere and biosphere.
5. The Biosphere
❖ The Biosphere is the earth’s relatively thin zone of air, soil, and water that is
capable of supporting life, ranging from about 10 km into the atmosphere to the
deepest ocean floor.
❖ Life in this zone depends on the sun’s energy and on the circulation of heat and
❖ The biosphere is virtually contained by the geosphere and hydrosphere in the very
thin layer where these environmental spheres interface with the atmosphere,
❖ strongly influences, and in turn is strongly influenced by, the other parts of the
❖ strongly influence bodies of water, producing biomass requiredfor life in the
water and mediating oxidation-reduction reactions in the water.
❖ is involved with weatheringprocesses that break down rocks in the geosphere and
convert rock matter to soil.
❖ Simply this denotes the region of living organisms and their interactions with
the environmental segments, viz hydrosphere, atmosphere and lithosphere.
Both the biosphere and environment are influenced considerably by each
❖ Thus oxygen and carbon dioxide levels of atmosphere depend entirely on the
❖ As a matter of fact, green plants alone are responsible for the accumulation
of oxygen in the atmosphere, through photosynthesis and decay, the original
atmosphere having been devoid of oxygen. The biological world, in general is
intimately related with energy flow and water chemistry.
❖ The protective blanket of gases surrounding the earth which sustains life on
the earth and saves it from the hostile environment of outer space.
❖ It has a thickness of more than 1100 km about half its mass is concentrated in
the lower 5.6 km.
❖ It absorbs most of the cosmic rays from outer space and a major portion of
electromagnetic radiation from the sun. It transmits only near ultraviolet,
visible, near infrared radiation (300-500nm) and radio waves while filtering
out tissue, damaging ultraviolet radiation below about 300nm.
❖ The atmosphere plays a major role in maintaining the heat balance of the
earth, through adsorption of infrared radiations emitted from the sun and re-
emitted from the earth.
❖ The major components of the atmosphere are nitrogen and oxygen while the
minor components are argon, carbon dioxide and some trace gases.
8. ❖ The atmosphere is the source of oxygen (essential for life on earth) and
carbon dioxide (essential for plant photosynthesis)
❖ It also supplies nitrogen which N-fixing bacteria and ammonia manufacturing
plants utilize to yield chemically bound nitrogen essential for life.
❖ Furthermore it is vital carrier of water from ocean to land as part of
hydrological cycle thus acting as the condenser in a vast solar powered
❖ Unfortunately with progress in science and technology, man has been dumping
waste material into the atmosphere which is posing problem for the survival
of mankind itself on earth.
❖ Hydrosphere includes all type of water resources, oceans, seas, rivers, lakes
streams, reservoirs, glaciers, polar ice caps and ground water (water below
the earth surface).It covers approximately 70.8 percent of the surface of the
❖ It occurs in all spheres of the environment—About 97% of the earth water
supply in the ocean, where the high salt content does not permit its use for
the human consumption. About 2% of the water resources are locked in the
polar ice and glaciers while only 1% is available as fresh water (surface water,
rivers, lakes, streams and ground water) for human consumption and other
uses. It also occurs in many segments of the anthrosphere such as in boilers or
municipal water distribution systems.
❖ The major uses of water are for irrigation (30%) and thermal power plants
(50%) while other uses are domestic (7%) and industrial consumption (12%).
10. ❖ It is an essential part of all living systems and is the medium from which life
evolved and in which life exists.
❖ It carries energy and matter are through various spheres of the environment.
It leaches soluble constituents from mineral matter and carries them to the
ocean or leaves them as mineral deposits some distance from their sources.
❖ It carries plant nutrients from soil into the bodies of plants by way of plant
❖ It absorbs solar energy in oceans and this energy is carried as latent heat and
released inland when it again evaporates from oceans.
❖ The geosphere, is that part of the Earth upon which humans live and from
which they extract most of their food, minerals, and fuels.
❖ It is divided into layers, which include the solid, iron-rich inner core, molten
outer core, and the lithosphere – which consists of the upper mantle and the
❖ This is outer mantle of the solid earth, consisting of materials occurring in
earth crust and soil. The latter comprises a complex mixture of materials,
organic matter, air and water. The soil is the most important part of
❖ Environmental science is most concerned with the lithosphere.
❖ The lithosphere, extends to depths of 100 km and comprises two shells—the
❖ crust and upper mantle.
❖ The crust (the earth’s outer skin) is the layer that is accessible to humans and
is extremely thin compared to the diameter of the earth, ranging from 5 to 40
13. The Anthroposphere
❖ This is a name given to that part of the environment “made’’ or modified by
humans and used for their activities. Of course, there are some ambiguities
associated with this definition.
❖ The anthroposphere
➢ is a strongly interconnection to the biosphere.
➢ has strongly influenced the biosphere and change it drastically. For example,
destruction of wild life habitat has resulted in the extinction of vast numbers of
species, in some cases even before they are discovered; bioengineering of
organisms with recombinant DNA technology and older techniques of selection and
hybridization are causing great changes in the characteristics of organisms and
promise to result in even more striking alterations in the future.
❖ It is the responsibility of humankind to make such changes intelligently and to
protect and nurture the biosphere.