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ENVIRONMENTAL SCIENCE AND ENGINEERING
UNIT-I: ENVIRONMENT, ECOSYSTEMS AND BIODIVERSITY
Introduction of environment:
Environment means different things to different people. To some it means home: to others it may
refer to a village, a city a country or the whole world. It is formed by combining two words, viz.,
‘environ’ and ‘ment’ meaning ‘encircle’ or ‘all round’.
Definitions of Environment
Environment is defined as, “the sum of total of all the living and non – living things around us
influencing one another”.
TYPES OF ENVIRONMENT
Environment can be divided into two categories
1. Natural environment
2. Man – environment
1. Natural environment
Natural environment is characterized by natural components. All biotic (living) and abiotic
components (non-living) are created through a natural process. Creation of these biotic and abiotic
components do not require any human support.
Example: soil, water, air, tree, radiations, noise, etc.,
2. Man – environment
Man is the most powerful environmental agent. He modifies the environment using
modern technologies, according to his needs to a great extent. Thus the man-made environment
is created by man.
Example: House, road, schools, railway lines, parks, etc.,
SCOPE AND IMPORTANCE OF ENVIRONMENT
Environmental studies discipline has multiple and multilevel scopes. This study is important and
necessary not only for children but also foe everyone: literate or illiterate: employee or non – employee
etc., the scopes are summarized as follows:
1. To get an awareness and sensitivity to the total environment and its related problems
2. To motivate the active participation in environmental protection and improvement.
3. To develop skills for identifying and solving environmental problems
4. To know the necessity of conservation of natural resources
5. To evaluate environmental programmers in terms of social, economic, ecological, and aesthetic
factors
IMPORTANCE OF ENVIRONMENTAL STUDY
Environmental study is based upon a comprehensive view of various environmental systems. It aims to make
the citizens competent to do scientific work to find out practical solutions to current environmental problems.
1. World population is increasing at an alarming rate especially in developing countries.
2. The natural resources endownent in the earth are limited
3. The methods and techniques of exploiting natural resources are advanced
4. The resources are over-exploited and there is no foresight of leaving the resources to the future
generations.
5. The unplanned exploitation of natural resources lead to pollution of all types and at all levels
6. The pollution and degraded environment seriously affect the health of all living things on earth,
including man
7. Education and training are needed to save the biodiversity and species extinction
8. The urban areas, coupled with industries, are the major sources of pollution.
PUBLIC AWARNESS TO ENVIRONMENTAL ISSUES/STUDIES
Need For Public Awareness:
The United Nations Conference on Environment and Development held at Reo de Janeiro in
1992 (popularly known as „Earth Summit‟) and world summit on sustainable development at
Johannesburg in 2002, have highlighted the key issues of global environmental concern. They have
attracted the attention of people.
Any government at its own cannot achieve the goals of clear environment until the public
participate in action. Public participation is possible only when the public is aware about the
ecological and environmental issues. Eg. Ban- the littering of polythene.
Methods to propagate environmental Awareness:
1. Among students through education introducing environmental studies in the curriculum.
2. Among public through mass media- environmental programmmes through TV, radio etc.
3. Among decision makers, planners, leaders etc.
Role of NGOs
1. Advise the government in interacting with ground level people
2. Organize public meetings to create environmental awareness
Eg. Recent report of „centre for science and environment‟ on permissible limits of pesticides in
cola drinks.
Public awareness is needed in the area
1. Study of natural resources-conservation and management
2. Ecology and biodiversity conservation
3. Environmental Pollution and prevention
4. Social issues related to development and environment
5. Human population and environment
CONCEPT OF ECOSYSTEM
Living organisms cannot be isolated from their non-living environment because the later
provides materials and energy for the survival of the farmer. An ecosystem is therefore defined as a
natural functional ecological unit comprising of living organisms and their non-living environment
that interact to form a stable self supporting system.
Eg. Pond, lake, desert, grassland, forest, etc.
ECOSYSTEMS
Ecology – earnest Haeckal- 1869 –derived from “oikos‟ – home , logy – study-deals with the
study of organisms in their natural home interacting with their surroundings.
Ecosystem – Tansley (1935) – self regulating group of biotic communities of species interacting
with one another and with their non- living environment exchanging energy and matter
ECOSYSTEM CHARACTERISTICS
Structural features – composition and organization of biological communities and abiotic
components constitute – Structure of Ecosystem
Biotic structure – Plants, animals, microorganisms – form biotic components – nutritional
behavior and status in the ecosystem – producers or consumers – how do they get their food.
STRUCTURE OF ECOSYSTEM
1. Abiotic or non-living components or physical components
2. Biotic or Living components
3. Energy components.
Abiotic Components:
Abiotic components enter the body of living directly or indirectly take part in metabolic activities
and return to environment.
Abiotic components are as follows
1. Atmosphere – The cover of air that envelopes the earth is known as atmosphere. Compostion –
Nitrogen-78%, oxygen- 2%, other gases- 1%
2. Lithosphere or Interior of Earth – Solid Earth – Radius 6371- density -5.5
3. Hydrosphere – 97% earth is water is in oceans fresh water-3% 97% earth‟s water is in oceans –
Fresh water – 3%.
STRUCTURE OF ATMOSPHERE
Five Layers
1. Troposphere – lower portion – extends from 0-18 kms, temperature-2.
2. Stratosphere -18- 50 kms- Temperature (-2ºC to -56ºC ) - Ozone layer3.
3. Mesosphere- extends from 50-85 kms- Temperature drops to (-95ºC)4.
4. Ionosphere or Thermosphere – extends up to 500 kms. Temperature – raises up to 1200ºC5.
5. Exosphere – extends up to 1600 km- temperature very high due to solar radiation
Functions of Atmosphere:
It maintains heat balance on the earth by absorbing IR radiation.
Oxygen– support life on living organism.
Co2 - essential for photosynthetic activity of plants.
N - essential nutrient for plant growth.
2
Interior of Earth or Lithosphere:
Three major Zones
1. Crust – top most layer- solid thickness 30 – 40 Km in continents and 5– 6 km in oceans.
Rocks of the earth crust– 3 types– Igneous, Sedimentary, Metamorphic.
2. Mantle – average density 3.3 – Thickness – 2860 – density increases with depth.
3. Core – outer core – solid, inner core – liquid). Depth – 2900 km from the surface of the earth –
density -12 – not exact composition.
Functions of Lithosphere:
1. It is home for human beings and wild life
2. It is store house of minerals and organic matter
Functions of Ecosystems - Ecosystem characteristics
Biotic structure – Plants, animals , microorganisms – form biotic components – nutritional behavior
and status in the ecosystem – producers or consumers – how do they get their food.
Producers – Photosynthesis – photoautotroph (auto – self, photo- light) Chemotrops or
Chemosynthetic organisms – Chemicals
Consumers – feeding upon other organisms
Types – Herbivores – Plant eating animals – primary consumers Eg ; rabbit
Carnivores – Feed on consumers – Secondary Consumers - feed on other carnivores – Tertiary/Consumers.
Omnivores – feed on both plants and animals – eg. Humans, rat, fox.
Detritivores - (Detritus feeder or Saprotrophs ) – feed on dead on organisms or decomposed matter eg;
beetles, termites, ants , crabs, earthworms.
Decomposers – nutrition breaking down in to complex organic molecules to simpler organicorganic
compounds – bacteria and fungi.
Abiotic Structure – physical and chemical components of an ecosystem.
Physical factors – sunlight, temperature, annual rainfall, soil type, water availability, water currents etc. –
strong influence on the ecosystem.
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