Environmental Studies Lecture Notes (3rd Semester) PDF

LECTURE NOTES ON ENVIRONMENTAL STUDIES (Th. 5) Name of the course: Diploma in Electrical Engineering. (3rd Semester) Notes Prepared by: DEBASIS CHOUDHURY. Designation : LECTURER IN ELECTRICAL....

LECTURE NOTES ON ENVIRONMENTAL STUDIES (Th. 5) Name of the course: Diploma in Electrical Engineering. (3rd Semester) Notes Prepared by: DEBASIS CHOUDHURY. Designation : LECTURER IN ELECTRICAL. College : UTKALMANI GOPABANDHU INSTITUTE OF ENGINEERING, ROURKELA.  CONTENTS SL. PAGE TOPICS NO. NO. SYLLABUS ix UNIT - I ENVIRONMENT, ECOSYSTEM AND BIODIVERSITY 1.1 ENVIRONMENT 01 1.1.1 Prerequisite discussions 01 1.1.2 Concepts 01 1.1.3 Scope of environmental science 01 1.1.4 Public awareness 02 1.1.5 Application 02 1.1.6 Risk and hazards in the environment 02 1.2 ECOSYSTEM 02 1.2.1 Prerequisite Discussions 03 1.2.2 Concepts 03 1.2.3 Energy Flow in Ecosystem 03 1.2.4 Food Chain 05 1.2.5 Food Web 05 1.2.6 Ecological Pyramids 06 1.2.7 Nitrogen Cycle 07 1.2.8 Oxygen Cycle 09 1.2.9 Carbon Cycle 09 1.2.10 Phosphorous Cycle 10 1.2.11 Ecological Succession 11 1.2.12 Forest Ecosystem (Terrestrial Ecosystem) 12 1.2.13 Grassland Ecosystem (Terrestrial Ecosystem) 14 1.2.14 Desert Ecosystem 14 1.2.15 Aquatic Ecosystems 14 1.2.16 Lakes & Pond Ecosystem 17 1.2.17 Marine Or Ocean Ecosystem 18 1.2.18 Significance Of Ecosystems 19 1.3 BIODIVERSITY 19 1.3.1 Prerequisite Discussions 19 1.3.2 Concepts : Levels of Biodiversity 19 1.3.3 Biogeographic Classification of India 19 1.3.4 Values of Biodiversity 20 1.3.5 Biodiversity at Global, National and Local Levels 20 1.3.6 India as a Megadiverse Nation 22 1.3.7 Hot- Spots of Biodiversity 24 1.3.8 Threats to Biodiversity 24 1.3.9 Endangered and Endemic Species of India 25 1.3.10 Conservation of Biodiversity 25 1.3.11 Significance of Biodiversity 26 GLOSSARY 26 REVIEW QUESTIONS 26 iii  UNIT - II ENVIRONMENTAL POLLUTION 2.1 ENVIRONMENTAL POLLUTION 27 2.1.1 Prerequisite discussions 27 2.1.2 Concepts 27 2.2 AIR POLLUTION 28 2.2.1 Causes of Air pollution 28 2.2.2 Effects of Air Pollution 28 2.2.3 Control measures 28 2.2.4 Mechanism of Peroxyacyl Nitrates(PAN) Generation 29 2.2.5 Formation of Smog 29 2.2.6 Formation of Oxygen 30 2.2.7 Control of Particulate and Gaseous Emission 31 2.2.8 Mitigation Procedures 32 2.3 WATER POLLUTION 33 2.3.1 Types of pollutions 33 2.3.2 Causes of Water Pollution 33 2.3.3 Effects of Water pollution 33 2.3.4 Control measures of water pollution 34 2.3.5 Physical and Chemical Characteristics of the Marine 34 Water 2.3.6 Physical and Chemical Characteristics of the Terrestrial 35 Water 2.3.7 Water Quality Parameters – Physical, Chemical and 36 Biological 2.3.8 Water Treatment 37 2.4 SOIL POLLUTION 37 2.4.1 Causes of Soil Pollution 37 2.4.2 Effects of Soil Pollution 37 2.4.3 Control measures 37 2.5 SOLID WASTE MANAGEMENT 37 2.5.1 Types 38 2.5.2 Cause 38 2.5.5 Effects 38 2.5.6 Control measures 38 2.5.7 Significance of Solid Waste Management 38 2.6 MARINE POLLUTION 38 2.6.1 Sources 38 2.6.2 Effects of marine pollution 39 2.6.3 Control measures of marine pollution 39 2.7 NOISE POLLUTION 39 2.7.1 Sounds and their decibel scale 39 2.7.2 Sources of noise pollution 40 2.7.3 Effects of noise pollution 40 2.7.4 Control of noise pollution 40 2.8 THERMAL POLLUTION 40 2.8.1 Causes 40 2.8.2 Effects 40 2.8.3 Control measures 40 iv 2.9 NUCLEAR HAZARDS 40 2.9.1 Causes 40 2.9.2 Effects 41 2.9.3 Control measures 41 2.10 ROLE OF AN INDIVIDUAL IN PREVENTION OF 41 POLLUTION 2.11 POLLUTION CASE STUDIES 41 2.11.1 Bhopal gas tragedy 41 2.11.2 Chernobyl Reactor Incident 42 2.11.3 Environmental Impact of Iceland Volcanic Eruption 42 2.11.4 Cashew in Kasargod, Kerala Poisonous Nuts 43 2.11.5 Groundwater Pollution in India 43 2.11.6 Marine Pollution in Tamil Nadu: Oceans Not Spared 43 2.11.7 Noise Hits Whales in Hong Kong 44 GLOSSARY 44 REVIEW QUESTIONS 44 UNIT - III NATURAL RESOURCES 3.1 NATURAL RESOURCES 45 3.1.1 Prerequisite Discussions 45 3.2 FOREST RESOURCES 45 3.2.1 Forest Functions 45 3.2.2 Commercial uses 46 3.2.3 Ecological uses 46 3.2.4 Over Exploitation of Forests 46 3.2.5 Ecological Significance of Forests 46 3.3 DEFORESTATION 47 3.3.1 Causes for Deforestation 47 3.3.2 Environmental effects /Consequences of deforestation 47 3.3.3 Conservation 47 3.4 TIMBER EXTRACTION AND MINING 48 3.5 DAMS – BENEFITS AND PROBLEMS 48 3.6 CASE STUDIES 48 3.6.1 Desertification in hilly regions of the Himalayas 48 3.6.2 Disappearing Tea gardens in Chhota Nagpur 48 3.6.3 Waning rain fall in Udhagamandalam 48 3.7 WATER RESOURCES 49 3.7.1 Over Utilization of Ground Water 49 3.7.2 Causes 50 3.7.3 Effects 50 3.7.4 Flood management 50 3.7.5 Drought 50 3.7.6 Causes 50 3.7.7 Effects 51 3.7.8 Control measures 51 3.8 CONFLICTS OVER WATER 51 3.8.1 Causes 51 3.8.2 Conflicts management 51 3.9 DAMS –BENEFITS AND PROBLEMS 51 v 3.10 MINERAL RESOURCES 52 3.10.1 Uses of minerals 52 3.10.2 Environmental impacts of mineral extraction 52 3.10.3 Impacts of mining 53 3.11 CASE STUDIES 53 3.11.1 Mining and quarrying in Udaipur 53 3.11.2 Mining in Sariska and Tiger Reserve in Aravallis 53 3.12 FOOD RESOURCES 54 3.12.1 World Food Problems 54 3.13 CHANGES CAUSED BY OVERGRAZING AND 54 AGRICULTURE 3.13.1 Impacts related to high yielding varieties 55 3.13.2 Problems associated with pesticide use 55 3.13.3 Water logging / salinisation 55 3.14 ENERGY RESOURCES 55 3.14.1 Use of alternate energy sources 55 3.15 LAND RESOURCE 56 3.15.1 Land Degradation 56 3.15.2 Man induced landslides 57 3.15.3 Soil erosion 57 3.16 ROLE OF INDIVIDUAL IN CONSERVATION OF NATURAL 57 RESOURCES 3.16.1 Conserve water 57 3.16.2 Protect soil 57 3.17 EQUITABLE USE OF RESOURCES FOR SUSTAINABLE 58 LIFE STYLE GLOSSARY 58 REVIEW QUESTIONS 58 UNIT - IV SOCIAL ISSUES AND THE ENVIRONMENT 4.1 PREREQUISITE DISCUSSIONS 59 4.2 FROM UNSUSTAINABLE TO SUSTAINABLE 59 DEVELOPMENT 4.2.1 Concept of sustainable development 59 4.2.2 Aim of sustainable development 59 4.2.3 Significance of sustainable development 59 4.3 URBAN PROBLEMS RELATED TO ENERGY 59 4.3.1 Urbanization 59 4.3.2 Causes Urban sprawl Urban energy requirement 4.3.3 Solution 60 4.4 WATER CONSERVATION 60 4.4.1 Water source 60 4.4.2 Need for water conservation 60 4.4.3 Ways of water conservation 60 4.4.4 Water conservation method 60 4.5 RAIN WATER HARVESTING 60 4.5.1 Objective 60 vi  4.5.2 Roof top rainwater harvesting 60 4.5.3 Advantages of rainwater harvesting 60 4.6 WATERSHED MANAGEMENT 61 4.6.1 Advantages of Watershed projects 61 4.6.2 Factors affecting Watershed projects 62 4.7 RESETTLEMENT AND REHABILITATION OF PEOPLE 62 4.7.1 Effects 62 4.8 ENVIRONMENTAL ETHICS 62 4.9 GREEN CHEMISTRY 62 4.10 GREEN HOUSE EFFECT AND GLOBAL WARMING 63 4.10.1 Causes 63 4.10.2 Effects 63 4.11 ACID RAIN 64 4.11.1 Effects of acid rain 65 4.11.2 Control measures 65 4.12 OZONE LAYER DEPLETION 64 4.12.1 Causes for ozone layer depletion 65 4.12.2 Effects 65 4.12.3 Control measures 66 4.13 NUCLEAR ACCIDENTS AND HOLOCAUST 67 4.14 WASTE LAND RECLAMATION 67 Reasons for formation 67 Ways of Wasteland reclaimed 67 4.15 CONSUMERISM AND WASTE PRODUCTS 67 4.16 ENVIRONMENT (PROTECTION) ACT, 1986 68 4.17 AIR (PREVENTION & CONTROL OF POLLUTION) ACT, 68 1981 4.18 WATER (PREVENTION AND CONTROL OF POLLUTION) 69 ACT, 1974 4.19 WILDLIFE [PROTECTION] ACT, 1972 69 4.19.1 Draw Backs of Wild Life (Protection) Act 69 4.20 FOREST (CONSERVATION) ACT, 1980 69 4.20.1 Draw Backs of the Forest (Conservation) Act 1980 69 4.21 THE BIOMEDICAL WASTE (MANAGEMENT AND 70 HANDLING) RULES; 1998 AND AMENDMENTS 4.22 SCHEME OF LABELING OF ENVIRONMENTALLY 71 FRIENDLY PRODUCTS (ECOMARK) 4.22.1 Objectives of the Scheme 71 4.22.2 Eco-Mark Logo 71 4.22.3 Scope of Eco-Mark 71 4.22.4 Unique feature of the Eco-Mark vis-a-vis other Eco- 72 Labels 4.22.5 Three Committees set-up for the Eco-Mark Scheme 72 4.22.6 Association with International Bodies 72 4.23 ENVIRONMENTAL LEGISLATION 72 4.23.1 Enforcement Of Environmental Legislation – Major 72 Issues 4.24 CENTRAL POLLUTION CONTROL BOARD (CPCB) 72 4.25 STATE POLLUTION CONTROL BOARD (SPCB) 73 4.26 PUBLIC AWARENESS 73 vii 4.27 DISASTER MANAGEMENT 73 4.27.1 Flood 73 4.27.2 Earthquake 73 4.27.3 Cyclone 74 4.27.4 Landslide 74 4.28 SIGNIFICANCE OF DISASTER MANAGEMENT 74 GLOSSARY 75 REVIEW QUESTIONS 75 UNIT – V HUMAN POULATION AND THE ENVIRONMENT 5.1 PREREQUISITE DISCUSSIONS 76 5.2 POPULATION GROWTH 76 5.2.1 Population characteristics and variation among nations 76 5.3 POPULATION EXPLOSION 76 5.4 FAMILY WELFARE PROGRAMME 77 5.5 ENVIRONMENT AND HUMAN HEALTH 77 5.6 HUMAN RIGHTS 77 5.7 VALUE EDUCATION 78 5.8 HIV/AIDS 79 5.8.1 HIV Test 79 5.8.2 Transmission of HIV 80 5.8.3 Prevention 80 5.9 WOMEN AND CHILD WELFARE 80 5.9.1 Poverty-environment-malnutrition 81 5.9.2 Child Development 81 5.10 ENVIRONMENTAL IMPACT ANALYSIS (EIA) 81 5.11 ROLE OF INFORMATION TECHNOLOGY IN 82 ENVIRONMENT AND HUMAN HEALTH 5.12 APPLICATION OF COMPUTERS IN THE FIELD OF 83 ENVIRONMENT & HUMAN HEALTH GLOSSARY 83 REVIEW QUESTIONS 84 REFERENCE BOOKS 85 QUESTION BANK 86-100 UNIVERSITY QUESTION PAPERS 101-106 viii  SYLLABUS GE6351 ENVIRONMENTAL SCIENCE AND ENGINEERING LTPC 3003 OBJECTIVES: To the study of nature and the facts about environment.  To finding and implementing scientific, technological, economic and political solutions to environmental problems.  To study the interrelationship between living organism and environment.  To appreciate the importance of environment by assessing its impact on the human world; envision the surrounding environment, its functions and its value.  To study the dynamic processes and understand the features of the earth‟s interior and surface.  To study the integrated themes and biodiversity, natural resources, pollution control and waste management. UNIT I ENVIRONMENT, ECOSYSTEMS AND BIODIVERSITY 12 Definition, scope and importance of Risk and hazards; Chemical hazards, Physical hazards, Biological hazards in the environment – concept of an ecosystem – structure and function of an ecosystem – producers, consumers and decomposers – Oxygen cycle and Nitrogen cycle – energy flow in the ecosystem – ecological succession processes – Introduction, types, characteristic features, structure and function of the (a) forest ecosystem (b) grassland ecosystem (c) desert ecosystem (d) aquatic ecosystems (ponds, streams, lakes, rivers, oceans, estuaries) – Introduction to biodiversity definition: genetic, species and ecosystem diversity – biogeographical classification of India – value of biodiversity: consumptive use, productive use, social, ethical, aesthetic and option values – Biodiversity at global, national and local levels – India as a mega-diversity nation – hot-spots of biodiversity – threats to biodiversity: habitat loss, poaching of wildlife, man-wildlife conflicts – endangered and endemic species of India – conservation of biodiversity: In-situ and ex-situ conservation of biodiversity. Field study of common plants, insects, birds Field study of simple ecosystems – pond, river, hill slopes, etc. UNIT II ENVIRONMENTAL POLLUTION 10 Definition – causes, effects and control measures of: (a) Air pollution (Atmospheric chemistry- Chemical composition of the atmosphere; Chemical and photochemical reactions in the atmosphere - formation of smog, PAN, acid rain, oxygen and ozone chemistry;- Mitigation procedures- Control of particulate and gaseous emission, Control of SO2, NOX, CO and HC) (b) Water pollution : Physical and chemical properties of terrestrial and marine water and their environmental significance; Water quality parameters – physical, chemical and biological; absorption of heavy metals - Water treatment processes. (c) Soil pollution - soil waste management: causes, effects and control measures of municipal solid wastes – (d) Marine pollution (e) Noise pollution (f) Thermal pollution (g) Nuclear hazards–role of an individual in prevention of pollution – pollution case studies – Field study of local polluted site – Urban / Rural / Industrial / Agricultural. UNIT III NATURAL RESOURCES 10 Forest resources: Use and over-exploitation, deforestation, case studies- timber extraction, mining, dams and their effects on forests and tribal people – Water resources: Use and overutilization of surface and ground water, dams-benefits and problems – Mineral resources: Use and exploitation, environmental effects of extracting and using mineral resources, case studies – Food resources: World food problems, changes caused by agriculture and overgrazing, effects of modern agriculture, fertilizer-pesticide problems, water logging, salinity, case studies – Energy resources: Growing energy needs, renewable and non renewable energy sources, use of alternate energy sources. Energy Conversion ix processes – Biogas – production and uses, anaerobic digestion; case studies – Land resources: Land as a resource, land degradation, man induced landslides, soil erosion and desertification – role of an individual in conservation of natural resources – Equitable use of resources for sustainable lifestyles. Introduction to Environmental Biochemistry: Proteins –Biochemical degradation of pollutants, Bioconversion of pollutants. Field study of local area to document environmental assets – river / forest / grassland / hill / mountain. UNIT IV SOCIAL ISSUES AND THE ENVIRONMENT 7 From unsustainable to sustainable development – urban problems related to energy – water conservation, rain water harvesting, watershed management – resettlement and rehabilitation of people; its problems and concerns, case studies – role of non-governmental organization- environmental ethics: Issues and possible solutions – 12 Principles of green chemistry- nuclear accidents and holocaust, case studies. – wasteland reclamation – consumerism and waste products – environment production act – Air act – Water act – Wildlife protection act – Forest conservation act –The Biomedical Waste (Management and Handling) Rules; 1998 and amendments- scheme of labeling of environmentally friendly products (Ecomark). enforcement machinery involved in environmental legislation- central and state pollution control boards- disaster management: floods, earthquake, cyclone and landslides. Public awareness. UNIT V HUMAN POPULATION AND THE ENVIRONMENT 6 Population growth, variation among nations – population explosion – family welfare programme – environment and human health – human rights – value education – HIV / AIDS – women and child welfare –Environmental impact analysis (EIA)- -GIS-remote sensing-role of information technology in environment and human health – Case studies. TOTAL : 45 PERIODS OUTCOMES: Environmental Pollution or problems cannot be solved by mere laws. Public participation is an important aspect which serves the environmental Protection. One will obtain knowledge on the following after completing the course.  Public awareness of environmental is at infant stage.  Ignorance and incomplete knowledge has lead to misconceptions  Development and improvement in std. of living has lead to serious environmental disasters TEXT BOOKS : 1. Gilbert M.Masters, "Introduction to Environmental Engineering and Science", 2nd edition, Pearson Education, 2004. 2. Benny Joseph, "Environmental Science and Engineering", Tata McGraw-Hill, New Delhi, 2006. REFERENCES : 1. Trivedi.R.K., "Handbook of Environmental Laws, Rules, Guidelines, Compliances and Standards", Vol. I and II, Enviro Media, 3rd edition, BPB publications, 2010. 2. Cunningham, W.P. Cooper, T.H. Gorhani, "Environmental Encyclopedia", Jaico Publ., House, Mumbai, 2001. 3. Dharmendra S. Sengar, "Environmental law", Prentice hall of India PVT LTD, New Delhi, 2007. 4. Rajagopalan, R, "Environmental Studies-From Crisis to Cure", Oxford University Press, 2005. x GE6351 ENVIRONMENTAL SCIENCE AND ENGINEERING UNIT - I ENVIRONMENT, ECOSYSTEM AND BIODIVERSITY 1.1 ENVIRONMENT Environmental science is the study of nature and the facts about environment. Environment can be defined as "all the social, economical, physical and chemical factors that surrounds man" or "all abiotic and biotic components around man-all living and non living things surrounds man". 1.1.1 PREREQUISITE DISCUSSIONS The word environment is derived from the French word ‘environ’ which means to ‘encircle or surround’. Objective of this course is to develop concern for our own environment which will lead us to act at our own level to protect the environment we all live in. Ever since people first recognized that their health and well-being were related to the quality of their environment, they have applied thoughtful principles to attempt to improve the quality of their environment. There are three reasons for studying the state of the environment. The first is the need for information that clarifies modern environmental concepts like equitable use of natural resources, more sustainable life styles etc. Second, there is a need to change the way in which we view our own environment, using practical approach based on observation and self learning. Third, there is a need to create a concern for our environment that will trigger pro- environmental action; including simple activities we can do in our daily life to protect it. 1.1.2 CONCEPTS According to ancient man the environment was the Panchaboodhas (i.e.) air, water, land, sky and energy. The human were disciples of nature. They were able to protect themselves from harmful one and protect the others. But according to modern man the environment is only air land and water. Exploitation of various earth resources to satisfy the increasing needs of human population has resulted in 1) depletion of various resources of earth 2) pollution. Principles of environmental education:  Examine the major environmental issues  Discover the root cause  Develop problem solving skills  Promote co-operation in solving problems  Emphasis active participation in prevention and solution to problems 1.1.3 SCOPE OF ENVIRONMENTAL SCIENCE  Studying the interrelationship between the components of environment.  Carrying out impact analysis and Environmental Audit  Preventing pollution from existing and new industries  Stopping the use of biological and nuclear weapons  Managing unpredictable disasters etc. SCE 1 Department of Mechanical Engineering GE6351 ENVIRONMENTAL SCIENCE AND ENGINEERING 1.1.4 PUBLIC AWARENESS Environmental Pollution or problems cannot be solved by mere laws. Public participation is an important aspect which serves the environmental Protection.  Public awareness of environmental issue is at infant stage  30-40% of public of developing country are aware of environmental. Problems but they do not bother about it.  Ignorance and incomplete knowledge has lead to misconceptions.  Development and improvement in std. of living has lead to serious environmental disasters.  Debates on environmental Issues are treated as anti-developmental. 1.1.5 APPLICATION  Environmental science is essentially the application of scientific methods and principles to the study of environmental issues, so it has probably been around in some forms as long as science itself.  Environmental science is often confused with other fields of related interest, especially ecology, environmental studies, environmental education and environmental engineering.  Environmental science is not constrained with any one discipline and it is a comprehensive field. 1.1.6 RISK AND HAZARDS IN THE ENVIRONMENT Environmental risk due to various environmental hazards is an important topic for environmental engineers to recognise and understand in order to protect human society and ecosystems from harms or damages at local, regional or global scales. For example, to deal with contaminated soil and ground water at a brown field, risk and exposure assessment help engineers choose an optimal solution to either treat the hazard (e.g., to remove the contaminants from the soil and water) or reduce the exposure (e.g., to cover up the land with a barrier). A hazard is a threat to life, health, property, or ecosystems, i.e., it involves something that could potentially be harmful. Therefore, when a dormant hazard comes to fruition, it will cause physical damage or destruction, loss of life, or drastic change to the environment, and result in an incident, accident, emergency event, or disaster. Hazards may be classified into:  Chemical hazards – Combustion of Fossil fuels, industrial effluence, pesticides heavy metals.  Physical hazards – Radioactive and UV radiations, Global warming, Chlorofluro carbons, Noise etc.  Biological hazards – Bacteria, Viruses, Parasites. 1.2 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. SCE 2 Department of Mechanical Engineering GE6351 ENVIRONMENTAL SCIENCE AND ENGINEERING 1.2.1 PREREQUISITE DISCUSSIONS EO Wilson is an entomologist who envisioned that biological diversity was a key to human survival on Earth. He wrote ‘Diversity of life’ in 1993, which was awarded a prize for the best book published on environmental issues. He emphasised the risks to mankind due to manmade disturbances in natural ecosystems that are leading to the rapid extinction of species at the global level. An Indian ornithologist and naturalist, Salim Ali known as the "birdman of India", was among the first Indians to conduct systematic bird surveys across India. He was instrumental in creating the Bharatpur bird sanctuary (Keoladeo National Park) and prevented the destruction of what is now the Silent Valley National Park. He was awarded India's second highest civilian honour, the Padma Vibhushan in 1976. His autobiography, Fall of a sparrow, should be read by every nature enthusiast. He was our country’s leading conservation scientist and influenced environmental policies in our country for over 50 years. 1.2.2 CONCEPTS Ecology is the study of the distribution and abundance of organisms, the flows of energy and materials between abiotic and biotic components of ecosystems. Structure of Ecosystem 1. Abiotic or non-living components or physical components 2. Biotic or Living components 3. Energy components Function of organisms in an ecosystem  Producer (autotrophy): make food; plants, algae  Consumer (heterotrophy): eat other organisms  Decomposer: eat dead organic matter; bacteria and fungi Classes of Consumers  Herbivore – primary consumer – eats plants  Carnivores – secondary – meat eaters; eat herbivores  Tertiary – feed on carnivores  Omnivores – eat plants/animals 1.2.3 ENERGY FLOW IN ECOSYSTEM  All organisms must obtain a supply of energy and nutrients from their environment in order to survive.  The transformations of energy in an ecosystem begin first with the input of energy from the sun.  Because, it is the first step in the production of energy for living things, it is called “Primary production”.  Photosynthesis -- Chemical reaction where green plants use water & carbon dioxide to store the sun’s energy in glucose.  ENERGY is stored in glucose.  Glucose is stored as starch in plants  The majority of autotrophs are photoautotrophs that harness the energy of the sun and pass some of this energy onto consumers through feeding pathways.  The energy contained within producers and consumers is ultimately passed to the decomposers that are responsible for the constant recycling of nutrients. SCE 3 Department of Mechanical Engineering GE6351 ENVIRONMENTAL SCIENCE AND ENGINEERING  Thus, there is a one-way flow of energy through the biotic community and a cycling of nutrients between the biotic and abiotic components of the ecosystem  Energy flow cannot occur in reverse direction. Energy Flow  Starts from autotrophs (the producer level, i.e., first trophic level) to Heterotrophs including plant eaters or Herbivores (second trophic level) and so on.  The amount of energy decreases with successive trophic levels.  Only About 1% of energy from the sun is used by green plants & rest remains unutilized.  Similarly, there is loss of energy in each trophic level.  The transfer of food energy between the organisms in an ecosystem can be tracked by constructing food chains, food webs, pyramids of numbers, biomass and energy and energy flow diagrams. 1.2.4 FOOD CHAIN Plants by photosynthesis convert solar energy into protoplasm. Small herbivores consume the vegetable matter and convert into animal matter which in turn eaten by large carnivores.  A food chain may be defined as, “the transfer of energy and nutrients through a series of organisms with repeated process of eating and being eaten”.  In an ecosystem, all the organisms are linked together with one another by food relationship.  Each organism living or dead is potential food for some other organism. SCE 4 Department of Mechanical Engineering GE6351 ENVIRONMENTAL SCIENCE AND ENGINEERING Food Chain 1.2.5 FOOD WEB The food relationship between various organisms is being depicted by linking all the possible prey and predators of different food level. In an ecosystem linking of feeding habit relations will provide a food web or Interlocking pattern of several interlinked food chains is termed as FOOD WEB. SCE 5 Department of Mechanical Engineering GE6351 ENVIRONMENTAL SCIENCE AND ENGINEERING Food web in grassland ecosystem 1.2.6 ECOLOGICAL PYRAMIDS An”Ecological pyramid” is a graphical representation that shows the relative amounts of energy or matter contained within each tropic level in a food chain or food web. An ecological pyramid shows the relationship between consumers and producers at different tropic levels in an ecosystem. Ecological Pyramid SCE 6 Department of Mechanical Engineering GE6351 ENVIRONMENTAL SCIENCE AND ENGINEERING Types of Ecological Pyramids Pyramid of Numbers Shows the relative number of individual organisms at each tropic level. Pyramid of Numbers Pyramid of Biomass A pyramid of biomass represents the total dry mass (in grams per square meter of area) of all the organisms in each tropic level at a particular time. Pyramid of Biomass Pyramid of Energy A pyramid of biomass represents the rate of energy flow and/or productivity at successive tropic levels. The pyramids of energy are always upright. SCE 7 Department of Mechanical Engineering GE6351 ENVIRONMENTAL SCIENCE AND ENGINEERING Pyramid of Energy 1.2.7 NITROGEN CYCLE  Nitrogen is crucial for all organisms o Nucleic acids o Proteins o Chlorophyll  Nitrogen- 78% in Atmosphere  N2 is very stable and must be broken apart by organisms, combined with other atoms into a usable form. Nitrogen Cycle Nitogen cycle completes in 5 steps: 1) Nitrogen Fixation Conversion of N2 → NH3 Combustion, volcanic action, Lightning, Industrial processes (making fertilizer). Bacteria (Azotobactor, Clostridium, Nostoc etc.) 2) Nitrification Conversion of NH3 → NO3 Soil bacteria convert in a two step process. 3) Assimilation Roots absorb NH3, NH4, or NO3 and incorporate them into nucleic acids and protein. 4) Ammonification Amino acids and nucleotides are broken down into waste products NH3 or NH4 SCE 8 Department of Mechanical Engineering GE6351 ENVIRONMENTAL SCIENCE AND ENGINEERING 5) Denitrification The reduction of NO3 to N2.Denitrifying bacteria return some of the nitrogen to the atmosphere 1.2.8 OXYGEN CYCLE oxygen cycle is the circulation of oxygen in various forms through nature free in the air and dissolved in water. Oxygen is second only to nitrogen in abundance among uncombined elements in the atmosphere. Plants and animals use oxygen to respire and return it to the air and water as carbon dioxide (CO2). CO2 is then taken up by algae and terrestrial green plants and converted into carbohydrates during the process of photosynthesis, oxygen being a by-product. The waters of the world are the main oxygen generators of the biosphere; their algae are estimated to replace about 90 percent of all oxygen used. The generalized oxygen cycle Oxygen is involved to some degree in all the other biogeochemical cycles. For example, over time, detritus from living organisms transfers oxygen-containing compounds such as calcium carbonates into the lithosphere. Despite the burning of fossil fuel and the reduction of natural vegetation (on land and in the sea), the level of atmospheric oxygen appears to be relatively stable because of the increase in plant productivity resulting from agricultural advances worldwide. 1.2.9 CARBON CYCLE  Carbon enters plants, etc., as CO2 o Bacteria process carbon in a fashion that allows it to be recycled. o Obtain energy from the molecules, and convert carbohydrates to carbon dioxide as a result of respiration.  Photosynthesis removes carbon from the abiotic environment (fixes carbon into organic molecules)  Carbon moves through food chain through consumption of one organisms by another SCE 9 Department of Mechanical Engineering GE6351 ENVIRONMENTAL SCIENCE AND ENGINEERING  Cellular respiration, combustion, and erosion of limestone return carbon to the atmosphere, water and abiotic environment. Carbon Cycle The source of atmospheric carbon dioxide is variable but only plants can utilize atmospheric carbon directly. 1.2.10 PHOSPHOROUS CYCLE  The only cycle that does not have a gaseous state.  Inorganic phosphate PO43- is released from rocks and sediments through the action of erosion. Phosphorous Cycle SCE 10 Department of Mechanical Engineering