MULTIDISCIPLINARY NATURE OF ENVIRONMENTAL SCIENCE

1. MULTIDISCIPLINARYNATURE OFENVIRONMENTAL SCIENCE Prepared by: Prof. S. K. Sharma

2. 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 (non-living) 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

3. 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

4. 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.

5. Composition Of Atmosphere • Various gases and water vapour • In its uppermost reaches it is charged with subatomic particles • Amount of water vapourpresent 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.

6. Principal Gases of Dry-Air in the Lower Atmosphere (near ground level)

7. 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

8. Structure of Atmosphere along with Temp. Profile ofAtmosphere and Related Phenomenon.

9. 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

10. 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.

11. 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.

12. 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

13. 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

14. 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

15. 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.

16. A Typical Analysis of Precipitation

17. The most common dissolved salts are chloride and sulphate of sodium, magnesium, calcium, potassium and strontium.

18. Major Elements of Sea Water

19. Major Elements of River and Lake Waters

20. Ground Water • Ground water generally, is clear but harder than the surface waters • Contain dissolved impurities like iron, magnesium, calcium, chloride, fluoride, dissolved gases

21. 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.

22. 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 solid-waste forms too are discharged into the biosphere

23. 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

24. 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

25. Recent example of chemical toxin that threatens human health is the chemical dioxin (2, 3, 7, 8-tetrachloro-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 TajMahal, 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

26. 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

27. 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 short-sightedness 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

28. 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.

29. ANY QUESTION??