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Environmental Science (Ce-101) Unit- I

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Environmental Science (Ce-101) Unit- I Lecture Notes of Environmental Science ENVIRONMENTAL SCIENCE (CE-101) UNIT- I Introduction to Environmental Science: The science of Environment studies is a multi-disciplinary science because it comprises various branches of studies like chemistry, physics, medical science, life science, agriculture, public health, sanitary engineering etc. It is the science of physical phenomena in the environment. It studies of the sources, reactions, transport, effect and fate of physical a biological species in the air, water and soil and the effect of from human activity upon these. Environment – The word environment comes from the greek word “environner” meaning surroundings around us. Scope of Environmental studies: The environment consists of four segments as under: 1. Atmosphere: The atmosphere implies the protective blanket of gases, surrounding the earth: It sustains life on the earth. It saves it from the hostile environment of outer space. It absorbs most of the cosmic rays from outer space and a major portion of the electromagnetic radiation from the sun. It transmits only here ultraviolet, visible, near infrared radiation (300 to 2500 nm) and radio waves. (0.14 to 40 m) while filtering out tissue-damaging ultraviolet waves below about 300 nm. The atmosphere is composed of nitrogen and oxygen. Besides, argon, carbon dioxide, and trace gases. 2. Hydrosphere: The Hydrosphere comprises all types of water resources oceans, seas, lakes, rivers, streams, reservoir, polar icecaps, glaciers, and groundwater. Nature 97% of the earth’s water supply is in the oceans, Prepared by: Er. Arshad Abbas Deptt. of Civil Engg. KMCUAF University Lucknow About 2% of the water resources are locked in the polar icecaps and glaciers. Only about 1% is available as fresh surface water-rivers, lakes streams, and ground water fit to be used for human consumption and other uses. 3. Lithosphere: Lithosphere is the outer mantle of the solid earth. It consists of minerals occurring in the earth’s crusts and the soil e.g. minerals, organic matter, air and water. 4. Biosphere: Biosphere indicates the realm of living organisms and their interactions with environment, viz atmosphere, hydrosphere and lithosphere. Indian Scenarios of Natural Resources: What are natural resources ? Soil, water and vegetation are three basic natural resources. The survival of creation depends upon them and nature has provided them as assets to human beings. Natural Resource Management: Natural Resources Management (NRM) refers to the sustainable utilization of major natural resources, such as land, water, air, minerals, forests, fisheries, and wild flora and fauna. Together, these resources provide the ecosystem services that underpin human life. Concern for Natural Resources Management: 1. Over‐exploitation of natural resources by growing population resulted in various severe problems. Destruction of vegetation has resulted in land degradation, denudation (process of removing and breaking of rocks from the surface of earth), soil erosion, landslides, floods, drought and unbalanced ecosystems. 2. Natural resources (land, water, biodiversity and genetic resources, biomass resources, forests, livestock and fisheries) – the very foundation of human survival, progress and prosperity, have been degrading fast, and the unprecedented pace of their erosion is one of the root causes of the agrarian crisis (decline in the price of agriculture commodities) that the country is facing. 3. The downward rush of water has tremendous erosive force and moves millions of tonnes of fertile soil during the rainy season. 4. Denuded hills and other wastelands pose serious problems which adversely affect agriculture and human life in the region. Landslides and landslips block hill roads and Prepared by: Er. Arshad Abbas Deptt. of Civil Engg. KMCUAF University Lucknow charge streams with heavy sediment loads. 5. Due to impacts of climate change like global warming, many adverse changes are taking place in the nature as well as in the natural resources. Conservation of Natural Resources: Conservation is the proper management of a natural resource to prevent its exploitation, destruction or degradation. Conservation is the sum of activities, which can derive benefits from natural resources but at the same time prevent excessive use leading to destruction or degradation. The nature provides us all our basic needs but we tend to overexploit it. If we go on exploiting the nature, there will be no more resources available in future. There is an urgent need to conserve the nature. Some of the needs are: 1. To maintain ecological balance for supporting life. 2. To preserve different kinds of species (biodiversity). 3. To make the resources available for present and future generation. 4. To ensure the survival of human race. 5. To preserve and conserve the natural resources. Green Chemistry Green chemistry is the utilization of set of principles that will help reduce the use and generation of hazardous substances during the manufacture and application of chemical products. Green chemistry aims to protect the environment not by cleaning up, but by inventing new chemicals processes that do not pollute the environment. It is rapidly developing and an important area in the chemical science. Principles of Green Chemistry: The principles of green chemistry were given by Anastas and Warner. The Green chemistry is based on twelve principles: 1. Prevention - Hundreds of tonnes of hazardous waste are released into air, water and land by industry everyday and every hour. It is better to prevent waste than to treat or clean up waste after it has been created. Ability of chemistry to redesign chemical transformation to minimize generation of hazardous waste is important step. The chemical process should be designed in Prepared by: Er. Arshad Abbas Deptt. of Civil Engg. KMCUAF University Lucknow such a way that less or no byproducts (HCL, Cl and H2) are formed. 2. Atom Economy - Synthetic methods should be designed to maximize the incorporation of all materials used in the process into the final product. 3. Less Hazardous Chemical Syntheses - Wherever practicable, synthetic methods should be designed to use and generate substances that possess little or no toxicity to human health and environment. 4. Designing Safer Chemicals - Chemical products should be designed in such a way that they have high efficiency and low toxicity. Medical drug to be designed in markets should first put on trials to check their toxic effect on human beings. If toxic, alternatives are prepared such that only toxicity is reduced and not their efficiency. 5. Safer Solvents and Auxiliaries - The use of auxiliary substances like solvents, separation agents should be avoided whenever possible. Solvents such as acetone, benzene, ether are highly inflammable. If solvent is necessary, water is good medium which is eco-friendly solvent that do not form smog or destroy ozone layer. 6. Design for Energy Efficiency Energy –The design processes should be aimed to increase the energy efficiency. Carrying out reactions at ambient temperatures and pressures wherever possible by using catalyst and lesser use of fossil fuels. 7. Use of Renewable Feedstocks - A raw material or feedstock should be renewable rather than depleting whenever technically and economically practicable. 8. Reduce Derivatives - Unnecessary derivatization (use of blocking groups, protection/ deprotection, temporary modification of physical/chemical processes) should be minimized or avoided if possible, because such steps require additional reagents and can generate waste. 9. Catalysis - Catalytic reagents are preferred over stoichiometric reagents to minimize waste. A catalyst is used in small amount to carry single reaction many times while stoichiometric reagent is used in excess and works only once. Also the catalytic reactions are faster as compared to stoichiometric reactions. 10. Design for Degradation - Chemical products should be designed so that at the end of their function they break down into non-hazardous substance and do not accumulate in environment. For example, use of biological insecticides instead of DDT that remain in soil and causes pollution. 11. Real-time analysis for Pollution Prevention- Analytical methods need to be developed to allow online monitoring and control prior to the formation of hazardous substances. For example, in the preparation of ethylene glycol, if reaction condition is not monitored perfectly, toxic substances are produced at high temperatures. 12. Inherently Safer Chemistry for Accident Prevention- Substances and the form of a substance used in a chemical process should be chosen to minimize the potential for chemical Prepared by: Er. Arshad Abbas Deptt. of Civil Engg. KMCUAF University Lucknow accidents, including releases, explosions, and fires. Environmental laws/Acts Environmental laws is the collective term describing the network of treaties, statutes, regulations, and common and customary laws addressing the effects of human activity on the natural environment. The environmental legislation is a collection of many laws and regulations aimed at protecting the environment from harmful actions. Environment Protection Act (EPA), 1986 This is an umbrella legislation designed to provide a framework for the co-ordination of central and state authorities established under the water prevention and control act, 1974 and air prevention and control act, 1981. Under this act, the central government is empowered to take measures necessary to protect and
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