Download MULTIDISCIPLINARY NATURE OF ENVIRONMENTAL SCIENCE

MULTIDISCIPLINARY
NATURE OF
ENVIRONMENTAL SCIENCE
Prepared by:
Prof. S. K. Sharma
Environment
• Man inhabits two worlds
– natural-world
– built-world
• Environment can be defined as one’s surroundings; which
includes everything around the organism, i.e., abiotic (nonliving) and biotic (living)
• Abiotic environment consists of soil, water and air
• Biotic environment includes all other organisms
– Global environment consists of three segments;
– atmosphere
– hydrosphere
– lithosphere
Atmosphere
• Blanket of gases and suspended liquids and
solids that entirely envelops the earth
• Extends up toSeveral thousand kilometers
• ‘Pure air’ is colourless, odourless, tasteless
• It absorbs most of the cosmic rays from outer
space and a major portion of the
electromagnetic radiation (EMR) from the sun
• Air has the density of 1.208 Kg/m3. At sea
level, the air pressure is 1033.6 g/sq. cm i.e.
76 cm of Hg
• As it is compressible its density decreases with
altitude
• life would be impossible without atmosphere.
• It helps in maintaining habitable temperature
on earth.
Composition Of Atmosphere
• Various gases and water vapour
• In its uppermost reaches it is charged with
subatomic particles
• Amount of water vapour present in the
atmosphere is very small but its importance is
very great
• Water enters the atmosphere by evaporation
from the hydrosphere (and by transpiration), and
leaves the atmosphere by precipitation. It is a
never ending two-way traffic.
Principal Gases of Dry-Air in the Lower Atmosphere (near ground level)
Structure Of The Atmosphere
• Vertical extent of the atmosphere is difficult to
ascertain, as it has no sharp boundary with
extraterrestrial space
• On the basis of temperature profile and other
related phenomena, atmosphere is divided
into four major layers (or shells), viz.,
Troposphere, Stratosphere, Mesosphere and
Thermosphere
Structure of Atmosphere along with Temp. Profile of
Atmosphere and Related Phenomenon.
Troposphere
• lower portion of the atmosphere extending upto
about 8 km at the poles and 16 km at the equator
• This layer is of greatest interest in pollution
control, the air which we breathe is the air in the
troposphere.
• Recent changes in troposphere involves the
phenomenon of Acid Rains
• Uniform decrease in temperature with increase in
altitude (about 6°C/km) to a minimum of – 50° or
– 60°C
Stratosphere
• Temperature is nearly constant upward to
about 20 km and then increases upto a
maximum of 0°C near its outer limit,
Stratopause, due to absorption of ultraviolet
radiation by ozone.
Mesosphere
• The temperature decreases slowly with the
altitude but then sharply to a minimum of
about – 75°C near the Mesopause, at 80 km.
• Meteorites burn and disintegrate, as they
experience increasing friction, in this layer.
Thermosphere
• Temperature again rises to very high values
and at times approaches 2,000°C and even
more at about 500 km depending upon solar
activity
Ionosphere
• Atmospheric layer at 100 to 400 km delimited
on the basis of ionized particles
• Radiowaves are reflected by ionized layers at
great heights
• Boundary layer: closest to the earth’s surface
Hydrosphere
• Oceans, seas, rivers, streams, glaciers, lakes,
reservoirs, polar ice caps and the shallow
groundwater bodies that interflow with the
surface water
• 70.8% of the earth’s surface is covered with water
mainly in the form of oceans
• 97% of total water (1360M Km3) in the oceans
and inland seas
• less than 1% is available as fresh water, for
human consumption
Composition of Natural Waters
• The pure water is the one which contains two
parts of hydrogen and one part of oxygen by
volume
• Tetrahedral arrangement in which each water
molecule is surrounded by four neighbouring
water molecules.
• Water may acquire impurities at the very
moment of condensation.
A Typical Analysis of Precipitation
• The most common dissolved salts are chloride and
sulphate of sodium, magnesium, calcium,
potassium and strontium.
Major Elements of Sea Water
Major Elements of River and Lake Waters
Ground Water
• Ground water generally, is clear but harder
than the surface waters
• Contain dissolved impurities like iron,
magnesium, calcium, chloride, fluoride,
dissolved gases
Lithosphere
• Top crust of the earth
• Thickest in the continental regions where it
has an average thickness of 40 km and thinest
in the oceans where it may have a maximum
thickness of 10 to 12 km
• lithosphere is the soil mantle (that wraps the
core of the earth) in which the biological
activities take place.
Biosphere
• First suggested by an Austrian geologist
Edward Suess, nearly a century ago
• All the life-forms of earth, including man, live
in it
• Waste products in gaseous, liquid and solidwaste forms too are discharged into the
biosphere
Impacts Of Humans Upon The
Environment
• Humans can thrive and flourish beyond natural
constraints
• Anthropogenic (man-induced) pollutants have
overloaded the system and the natural
equilibrium is disturbed.
• With the dawn of the industrial revolution
humans turned their attention to other needs
beyond those associated with survival.
• Automobiles, household appliances, processed
foods and beverages has changed scenario
Impact Of The Environment Upon
Humans
• Very negative impact on the health, aesthetic and
cultural pleasures, and economic opportunities of
humans
• A wide range of communicable diseases can be
spread through the segments of the environment
by human and animal waste products
• High concentrations of SOx, NOx, CO2, CO, SPM,
and other contaminants in the atmosphere pose
direct and indirect threats to human health
• Recent example of chemical toxin that threatens
human health is the chemical dioxin (2, 3, 7, 8tetrachloro-dibenzoparadioxin) which is an
unintentional by-product formed in the
production of some herbicides, disinfectants and
wood-preserving compounds
• Uncontrolled dumps, littered streets and
highways, etc. give aesthetically displeasing effect
of improper solid-waste disposal
• The Taj Mahal, frescoes of Ajanta, Statue of
Liberty, the Dal Lake in Kashmir are now in the
increasing danger of being destroyed by the
constituents of a polluted atmosphere
Environmental Science
• Systematic study of our environment and our proper
place in it
• Require a solid foundation in the natural sciences
(physics, chemistry, biology, mathematics and
engineering), in addition to fields such as anthropology,
sociology, history, art, literature, religion, law,
economics, management, paleantology, ecology,
political science
• Must be aware of the cultural and historical context in
which we make decisions about the environment and
understand ways in which choices are made and
implemented
Need For Public Awareness
• Man has acquired the capacity to change the
environment more than any other organism on
this planet
• Human needs and greeds coupled with shortsightedness have disturbed the delicate
ecological balance
• Humans are depleting and degrading the vital
life-supporting systems including air, water and
land which belong to the entire living world
• We have a special environmental responsibility to
ourselves and to other follow living beings.
• We have to conserve the environment not merely
for the preservation of the rich biological diversity,
natural resources or aesthetic value, but for sheer
survival.
ANY QUESTION??