Environmental Science PDF - DIP130EN

ENVIRONMENTAL SCIENCE Subrat Roy KHANNA BOOK PUBLISHING CO. (P) LTD. PUBLISHER OF ENGINEERING AND COMPUTER BOOKS 4C/4344, Ansari Road, Darya Ganj, New Delhi-110002 Phone: 011-23244447-48 Mobile: +91-99109 09320 E-mail: [email protected] Website: www.khannabooks.c...

ENVIRONMENTAL SCIENCE Subrat Roy KHANNA BOOK PUBLISHING CO. (P) LTD. PUBLISHER OF ENGINEERING AND COMPUTER BOOKS 4C/4344, Ansari Road, Darya Ganj, New Delhi-110002 Phone: 011-23244447-48 Mobile: +91-99109 09320 E-mail: [email protected] Website: www.khannabooks.com  Dear Readers, To prevent the piracy, this book is secured with HIGH SECURITY HOLOGRAM on the front title cover. In case you don’t find the hologram on the front cover title, please write us to at [email protected] or whatsapp us at +91-99109 09320 and avail special gift voucher for yourself. Specimen of Hologram on front Cover title: Moreover, there is a SPECIAL DISCOUNT COUPON for you with EVERY HOLOGRAM. How to avail this SPECIAL DISCOUNT: Step 1: Scratch the hologram Step 2: Under the scratch area, your “coupon code” is available Step 3: Logon to www.khannabooks.com Step 4: Use your “coupon code” in the shopping cart and get your copy at a special discount Step 5: Enjoy your reading! Copyright © Reserved ISBN: 978-93-91505-65-3 No part of this publication may be Book Code: DIP130EN reproduced, stored in a retrieval system or transmitted, in any form or by any means, Environmental Science by electronic, mechanical, photocopying, Subrat Roy recording or otherwise without prior [English Edition] permission of the publisher. This book is sold subject to the condition First Edition: 2021 that it shall not, by way of trade, be lent, re-sold, hired out or otherwise disposed of without the publisher’s consent, in any form of binding or cover other than that in Published by: which it is published. Khanna Book Publishing Co. (P) Ltd. Visit us at: www.khannabooks.com Disclaimer: The website links provided by Write us at: [email protected] the author in this book are placed for CIN: U22110DL1998PTC095547 informational, educational & reference purpose only. The Publisher do not endorse these website links or the views of To view complete list of books, the speaker/ content of the said weblinks. Please scan the QR Code: KPH In case of any dispute, all legal matters to be settled under Delhi Jurisdiction only. Printed in India. (ii)  Acknowledgement T he author is grateful to AICTE for their meticulous planning and execution to publish the technical book for Diploma students. I sincerely acknowledge the valuable contributions of the reviewer of the book Prof. S P Mishra, for making it students’ friendly and giving a better shape in an artistic manner. This book is an outcome of various suggestions of AICTE members, experts and authors who shared their opinion and thoughts to further develop the engineering education in our country. It is also with great honour that I state that this book is aligned to the AICTE Model Curriculum and in line with the guidelines of National Education Policy (NEP)-2020. Towards promoting education in regional languages, this book is being translated in scheduled Indian regional languages. Acknowledgements are due to the contributors and different workers in this field whose published books, review articles, papers, photographs, footnotes, references and other valuable information enriched us at the time of writing the book. Finally, I like to express my sincere thanks to the publishing house, M/s. Khanna Book Publishing Company Private Limited, New Delhi, whose entire team was always ready to cooperate on all the aspects of publishing to make it a wonderful experience. Subrat Roy (v)  Preface The book titled “Environmental Science” is an outcome of our experience in the area of environmental engineering & science. The very purpose of writing this book is to develop basic concept of environmental science in the diploma students as well as enable them to get insight into the subject. Keeping in mind the purpose of wide coverage as well as to provide essential supplementary information, we have included the topics recommended by AICTE, in a very systematic and orderly manner throughout the book. Efforts have been made to explain the fundamental concepts of the subject in the simplest possible way. During the process of preparation of the manuscript, I have considered the various standard text books and accordingly, developed sections like subjective and multiple choice questions etc. While preparing the different sections emphasis has also been given on the basic concepts of all the topics. All the topics are supported with relevant photographs to help students understanding the topic in a better way. There are total four units in the book. First unit deals with the ecosystem, second unit is about air and noise pollution, third unit discuss about renewable sources of energy and the fourth topic focuses on solid waste management, ISO 14000 & environmental management. It is important to note that in all the units, we have included the relevant websites and a list of reference books. The present book on “Environmental Science” is meant to provide a thorough grounding on the topics covered. This part of the environmental science will prepare students to apply the concept of various topics covered in the book to tackle the environmental challenges imposed in 21st century and address the related aroused questions. The subject matters are presented in a constructive manner which will certainly help students to guide society to maintain a pollution free eco-system. I sincerely hope that the book will inspire the students to learn and discuss the basic concepts of environmental science and will surely contribute to the development of a solid foundation of the subject. I welcome all beneficial comments and suggestions which will contribute to the improvement of the future editions of the book. It gives me immense pleasure to place this book in the hands of the teachers and students. It was indeed an immense pleasure to work on different aspects covered in the book. Subrat Roy (vii)  Outcome Based Education For the implementation of an outcome based education the first requirement is to develop an outcome based curriculum and incorporate an outcome based assessment in the education system. By going through outcome based assessments, evaluators will be able to evaluate whether the students have achieved the outlined standard, specific and measurable outcomes. With the proper incorporation of outcome based education there will be a definite commitment to achieve a minimum standard for all learners without giving up at any level. At the end of the programme running with the aid of outcome based education, a student will be able to arrive at the following outcomes (as per NBA guidelines): PO-1: Basic and Discipline specific knowledge: Apply knowledge of basic mathematics, science and engineering fundamentals and engineering specialization to solve the engineering problems. PO-2: Problem analysis: Identify and analyse well-defined engineering problems using codified standard methods. PO-3: Design/ development of solutions: Design solutions for well-defined technical problems and assist with the design of systems components or processes to meet specified needs. PO-4: Engineering Tools, Experimentation and Testing: Apply modern engineering tools and appropriate technique to conduct standard tests and measurements. PO-5: Engineering practices for society, sustainability and environment: Apply appropriate technology in context of society, sustainability, environment and ethical practices. PO-6: Project Management: Use engineering management principles individually, as a team member or a leader to manage projects and effectively communicate about well-defined engineering activities. PO-7: Life-long learning: Ability to analyse individual needs and engage in updating in the context of technological changes. (ix)  Course Outcomes After the completion of the course the students will be able to: CO-1: Analyse real life problems associated with the ecosystem. CO-2: Explain various types of pollution sources and its effect. CO-3: Apply various types of pollution control mechanism to curb environmental pollution. CO-4: Explain various sources of renewable energy and process of harnessing. CO-5: Explain solid waste management, ISO 14000 & Environmental management. Expected Mapping with Programme Outcomes Course (1- Weak Correlation; 2- Medium correlation; 3- Strong Correlation) Outcomes PO-1 PO-2 PO-3 PO-4 PO-5 PO-6 PO-7 CO-1 3 3 - - 3 - 2 CO-2 3 - - 1 3 - 2 CO-3 3 1 - 2 3 1 2 CO-4 3 - - 2 3 1 2 CO-5 3 - - - 3 - 2 (xi)  Abbreviations and Symbols List of Abbreviations General Terms Abbreviations Full form Abbreviations Full form Ag Argentum/Silver CFC Chloroflurocarbon As Arsenic CO Course Outcome ATP Adenosine Triphosphate DNA Dioxy-rhibo-nucleic acid Au Aurum/Gold HC Hydrocarbons C Carbon Hg Hydragyrum/Mercury CO Carbon Monoxide Mo Molybdenum CO2 Carbon Dioxide MSW Municipal Solid Waste CH4 Methane Ni Nickel Co Cobalt Pb Plumbum/Lead Cr Chromium UV Ultraviolet Cu Cuprum/Copper VoCs Volatile Organic Carbon Units Used Abbreviations Full form Abbreviations Full form cm Centimetre mm Millimetre µm Micrometer dB Decibels µN/m 2 Micro Newon/meter square Hz Hertz GW Gigawatt KW Kilowatt MW Megawatt TW Terawatt (xii)  List of Photographs and Figures Unit 1 Ecosystem List of Photographs: Photograph 1.1: Ecosystem Photograph 1.2: Ecosystem Photograph 1.3: Aquatic Ecosystem Photograph 1.4: Lentic and Lotic Ecosystem Photograph 1.5: Terrestrial Ecosystem Photograph 1.6: Biotic Components Photograph 1.7: Biotic and Abiotic Components Photograph 1.8: Food Chain Photograph 1.9: Food Web Photograph 1.10: Carbon Cycle Photograph 1.11: Nitrogen Cycle Photograph 1.12: Sulphur Cycle Photograph 1.13: Phosphorous Cycle Unit 2 Air and Noise Pollution List of Photographs: Photograph 2.1: Types of pollution Photograph 2.2: Pollutants Photograph 2.3: Sources of Air Pollution Photograph 2.4: Natural Sources of Air pollution Photograph 2.5: Manmade Sources of Air pollution Photograph 2.6: Catalytic converter Photograph 2.7: Sources of Noise Pollution List of Figures: Fig. 2.1: Typical Shaker Bag Filters Fig. 2.2: Typical Reverse air bag filter Fig. 2.3: Typical pulse jet bag filters (xiii)  Fig. 2.4: Typical cyclone separators Fig. 2.5: Packed bed counter flow scrubber Fig. 2.6: A schematic diagram of catalytic converter Unit 3 Renewable Sources of Energy List of Photographs: Photograph 3.1: Uses of Solar Energy Photograph 3.2: Flat Plate Collector and Its Working Principle Photograph 3.3: Schematic of Solar Pond Photograph 3.4: Solar Dryer Photograph 3.5: Solar Stills Photograph 3.6: Sources of Biomass Photograph 3.7: Utilization of Biogas Photograph 3.8: Wind Energy (Windmills) Photograph 3.9: Wind Energy in India Photograph 3.10: Hydrogen Energy Photograph 3.11: Geothermal Energy List of Figures: Fig. 3.1: Solar Water Heater Unit 4 Solid Waste Management, ISO 14000 and Environmental Management List of Photographs: Photograph 4.1: Solid Waste Generation Photograph 4.2: Biodegradable and Non- biodegradable Solid Waste Photograph 4.3: e-wastes Photograph 4.4: Biomedical Waste Photograph 4.5: Infectious Waste Photograph 4.6: Non-metallic Waste Photograph 4.7: Collection and Disposal of Solid Waste Photograph 4.8: Hazardous Waste Photograph 4.9: Concepts of Carbon Credit and Carbon Footprint (xiv)  Guidelines for Teachers To implement Outcome Based Education (OBE) knowledge level and skill set of the students should be enhanced. Teachers should take a major responsibility for the proper implementation of OBE. Some of the responsibilities (not limited to) for the teachers in OBE system may be as follows: Within reasonable constraint, they should manipulate time to the best advantage of all students. They should assess the students only upon certain defined criterion without considering any other potential ineligibility to discriminate them. They should try to grow the learning abilities of the students to a certain level before they leave the institute. They should try to ensure that all the students are equipped with the quality knowledge as well as competence after they finish their education. They should always encourage the students to develop their ultimate performance capabilities. They should facilitate and encourage group work and team work to consolidate newer approach. They should follow Blooms taxonomy in every part of the assessment. Bloom’s Taxonomy Teacher should Student should be Possible Mode of Level Check able to Assessment Students ability to Creating Design or Create Mini project create Students ability to Evaluating Argue or Defend Assignment Justify Students ability to Differentiate or Project/Lab Analysing distinguish Distinguish Methodology Students ability to use Operate or Technical Presentation/ Applying information Demonstrate Demonstration Students ability to Understanding Explain or Classify Presentation/Seminar explain the ideas Students ability to Remembering Define or Recall Quiz recall (or remember) (xv)  Guidelines for Students Students should take equal responsibility for implementing the OBE. Some of the responsibilities (not limited to) for the students in OBE system are as follows: Students should be well aware of each UO before the start of a unit in each and every course. Students should be well aware of each CO before the start of the course. Students should be well aware of each PO before the start of the programme. Students should think critically and reasonably with proper reflection and action. Learning of the students should be connected and integrated with practical and real life consequences. Students should be well aware of their competency at every level of OBE. (xvi)  Contents Foreword  iii Acknowledgment v Preface  vii Outcome Based Education ix Course Outcomes xi Abbreviations and Symbols xii List of Photographs and Figures xiii Guidelines for Teachers xv Guidelines for Students xvi Unit 1: Ecosystem 1-23 Unit specifics 1 Rationale 1 Pre-requisites 2 Unit outcomes 2 1.1 Introduction 3 1.2 Aquatic and terrestrial ecosystem 4 1.2.1 Natural ecosystem 4 1.2.2 Artificial ecosystems 7 1.3 Structure of ecosystem 7 1.3.1 Biotic (living) components 7 1.3.2 Abiotic (non-living) components 9 1.4 Food chain and food web 10 1.4.1 Food Chain 10 1.4.2 Food Web 11 1.5 Carbon, Nitrogen, Sulphur, Phosphorus cycle 12 1.5.1 Carbon Cycle 12 1.5.2 Nitrogen Cycle 13 1.5.3 Sulphur Cycle 15 1.5.4 Phosphorus Cycle 16 1.6 Global Warming 17 1.6.1 Ozone Depletion 18 1.7 Unit Summary 19 1.8 Interesting Facts 20 (xvii) 1.9 Innovative Activities 21 1.10 Exercises 21 1.11 Suggested Learning Resources 22 a) Reference Books 22 b) Open source software and website 22 c) Video Resources 22 Unit 2: Air and Noise Pollution 23-44 Unit specifics 23 Rationale 23 Pre-requisites 24 Unit outcomes 24 2.1 Introduction 25 2.2 Definition of pollution and pollutant 25 2.2.1 Natural and manmade sources of air pollution 28 2.3 Air Pollutants 29 2.3.1 Particulate pollutant 30 2.4 Gaseous Pollution Control 34 2.4.1 Absorber 34 2.4.2 Catalytic converter 35 2.4.3 Effects of air pollution due to Refrigerants, I.C., Boiler 36 2.5 Noise pollution 37 2.5.1 Sources of noise pollution 37 2.5.2 Measurement of noise pollution level 38 2.5.3 Effects of Noise pollution 38 2.5.4 Noise pollution (Regulation and Control) Rules, 2000 39 2.6 Unit Summary 40 2.7 Innovative Activities 41 2.8 Interesting Facts 42 2.9 Exercises 42 2.10 Suggested Learning Resources 44 a) Reference Books 44 b) Open source software and website 44 c) Video Resources 44 Unit 3: Renewable sources of Energy 45-72 Unit specifics 45 Rationale 45 (xviii) Pre-requisites 46 Unit outcomes 46 3.1 Introduction 47 3.2 Solar Energy 47 3.2.1 Flat Plate Collector (liquid and air) 48 3.2.2 Theory of flat plate collector 48 3.2.3 Importance of coating and Advanced collector 49 3.2.4 Solar pond, Solar water heater, Solar dryer and Solar stills 49 3.3 Biomass 53 3.3.1 Thermal characteristics of biomass as fuel 54 3.3.2 Anaerobic digestion 55 3.3.3 Biogas production mechanism 56 3.3.4 Utilization and storage of biogas 57 3.4 Wind energy 59 3.4.1 Current status and future prospects of wind energy 59 3.4.2 Wind energy in India 60 3.4.3 Environmental benefits and problem of wind energy 62 3.5 New Energy Sources 62 3.5.1 Different types new energy sources 62 3.5.2 Applications of Hydrogen energy 63 3.5.3 Applications of Ocean energy resources 64 3.5.4 Concept, origin and power plants of geothermal energy 64 3.6 Unit Summary 66 3.7 Innovative Activities 67 3.8 Interesting Facts 68 3.9 Exercises 69 3.10 Suggested Learning Resources 71 a) Reference Books 71 b) Open source software and website 71 c) Video Resources 72 Unit 4: Solid Waste Management, ISO 14000 & Environmental Management 73-100 Unit specifics 73 Rationale 73 Pre-requisites 74 Unit outcomes 74 4.1 Introduction 75 (xix) 4.2 Solid waste generation 75 4.2.1 Sources and characteristics of Municipal solid waste 76 4.2.2 Sources and Characteristics of e-wastes 77 4.2.3 Sources and Characteristics of Biomedical waste 79 4.3 Metallic wastes and Non-Metallic wastes 80 4.3.1 Non-metallic wastes from industries 80 4.4 Collection and disposal of MSW 82 4.4.1 Collection of Municipal Solid Waste (MSW) 82 4.4.2 Disposal of Municipal Solid Waste (MSW) 83 4.4.3 3R Principles 83 4.4.4 Energy recovery 84 4.4.5 Sanitary landfill 84 4.4.6 Hazardous waste 85 4.5 Air quality act 2004 86 4.5.1 Air pollution control act 1981 87 4.5.2 The Water (Prevention and Control of Pollution) act 1974 87 4.6 Structure and role of Central and State Pollution Control Board 88 4.6.1 Organisation of Central Pollution control Board 88 4.6.2 Functions of the Central Board at the National Level 88 4.6.3 Structure and Role of State Pollution Control Board 89 4.6.4 Functions of the Central Board as State Boards for the Union Territories 89 4.7 Carbon Footprint and Carbon Credit 90 4.7.1 Concept of Carbon Credit 91 4.8 Environmental management in fabrication industry 91 4.9 ISO14000 92 4.10 Unit Summary 92 4.11 Interesting Facts 94 4.12 Innovative Activities 95 4.13 Exercises 95 4.14 Suggested Learning Resources 96 a) Reference Books 96 b) Open source software and website 97 c) Video Resources 97 Important Day Related to Environment 98 CO and PO Attainment Table 98 Index 99-100 (xx)  1 Ecosystem UNIT SPECIFICS This unit deals with the following main aspects: Aquatic (Lentic and Lotic) and terrestrial ecosystem Structure of ecosystem, Biotic & Abiotic components Food chain and food web Carbon, Nitrogen, Sulphur, Phosphorus cycle Global Warming-Causes, effects, process, Green House Effect, Ozone depletion All the topics are well supported with relevant photographs for generating curiosity and creativity among the user of this book. A number of multiple choice as well as subjective type questions are given so that one can go through and solve them for practice. Learning resources like reference books, open resource software & website, video resources etc. are also given in the unit for further clarifications of concepts and doubts (if any). It may also be noted that for getting more information on various topics of interest, some QR codes have been provided in different sections which can be scanned for relevant supportive knowledge. RATIONALE Every creature depends on nature for their survival. It is therefore, not only essential but also moral responsibility of all of us to keep our environment clean and in a good condition. This unit deals with many important aspects related to the environment such as ecosystem, carbon, nitrogen, Sulphur & phosphorus cycles, global warming - cases & its effect. All these are directly related to the living organism including human beings. Like all other living beings, humans are dependent on natural ecosystem services for its survival. We need it to get the food we eat, the water we drink and to transform raw materials into our everyday products. So in order to keep our living environment in good conditions, it’s important that we preserve natural ecosystems. Similarly, global warming is also a matter of deep concern as it affects the life of human beings, plants and animals in many ways. It is a serious public health and environmental concern. Therefore, study of this unit will help diploma students to look insight into all the important aspects mentioned above and appreciate its importance. 2 Environmental Science PRE-REQUISITES High School Chemistry UNIT OUTCOMES Students will be able to: U1-O1: Explain ecosystem and its component. U1-O2: Compare food chain and food web. U1-O3: Differentiate aquatic and terrestrial ecosystems. U1-O4: Describe carbon, nitrogen, sulphur and phosphorus cycle. U1-O5: Explain causes and effect of global warning. U1-O6: Distinguish between greenhouse effect and ozone depletion. MAPPING OF UNIT OUTCOMES WITH THE COURSE OUTCOMES EXPECTED MAPPING WITH COURSE OUTCOMES Unit-1 (1-Weak Correlation; 2-Medium correlation; 3-Strong Correlation) Outcome CO-1 CO-2 CO-3 CO-4 CO-5 U1-O1 3 - - - - U1-O2 3 - - - - U1-O3 3 - - - - U1-O4 3 - - - - U1-O5 3 - - - - U1-O6 3 - - - - UNIT OVERVIEW 1.1 Introduction 1.2 Aquatic (Lentic and Lotic) and terrestrial ecosystem 1.3 Structure of ecosystem, Biotic & Abiotic components 1.4 Food chain and food web 1.5 Carbon, Nitrogen, Sulphur, Phosphorus cycle 1.6 Global Warming-Causes, effects, process, Green House Effect, Ozone depletion 1.7 Unit Summary 1.8 Interesting Facts 1.9 Innovative Activities 1.10 Exercises 1.11 Suggested Learning Resources  Ecosystem 3 1.1 INTRODUCTION The term “ecosystem” was first introduced by A.G.Tensley in 1935. He was an English Botanist and one of the pioneers in the field of ecology. Prof A.G.Tensley was educated at University College, and Trinity College, Cambridge, and taught at these universities including Oxford, where he served as a Professor of Botany until his retirement in 1937. Ecology is the study of organism, its surrounding environment, interaction of organism with each other and its surrounding environment. The environment refers to the things and conditions around the organism which directly or indirectly influence the life and development of the organism and their populations. Organism and environment are two non-separable factors in the ecology. Photograph 1.1: Ecosystem The ecosystem is the structural and functional unit of ecology where the living organisms interact with each other and with the surrounding environment. In other words, an ecosystem is a chain of interaction between organisms and their environment. An organism is mostly in the state of perfect balance with the environment. In any given area, all living organisms (such as algae, fungi, plants, microorganisms, animals and human beings) regularly and continuously interact among each other and also with non-living physical surroundings to maintain a balance in the nature. Photograph 1.2: Ecosystem 4 Environmental Science Among all the living organisms, human beings are the only organism who create imbalance in the nature to fulfil their needs such as food, shelter, clothing etc. Various developmental projects under taken in the recent past and also increase in the population have damaged the healthy and balanced nature. This imbalance nature created by uncontrolled human activities, has given rise to various environmental problems such as waste accumulation, depletion of ozone layer, global warming etc. 1.2 AQUATIC AND TERRESTRIAL ECOSYSTEM An ecosystem can be very small in size like an oasis in a desert, or very big like an ocean, spanning thousands of kilometers. There are two types of ecosystems: Natural ecosystem Artificial ecosystem 1.2.1 Natural ecosystem These ecosystems exist and operates in the nature by themselves without any human support and interference. It is a naturally produced biological environment found in nature. Few examples of natural ecosystems are: an ocean, a lake, a pond, a desert, a forest etc. Natural ecosystem can be of two types: Aquatic ecosystem Terrestrial ecosystem 1.2.1.1 Aquatic ecosystem Water supports many lives. Organisms which survive in water are called aquatic organisms. These organisms are dependent on water for their food, shelter, reproduction and all other life activities. An aquatic ecosystem includes a group of interacting organisms which are dependent on one another and their water environment for nutrients and shelter. Examples of aquatic ecosystem include oceans, lakes and rivers. It can be further divided into two types: Freshwater ecosystem Marine ecosystem Freshwater ecosystem: Freshwater ecosystem includes lakes, ponds, rivers and streams, wetlands, swamp, bog and temporary pools. They cover only a small portion of earth, nearly 0.8 per cent. These ecosystem provide habitat for 41% of the world`s fish species. Freshwater ecosystems are classified into two categories namely, lentic and lotic ecosystems. Lotic ecosystems represent flowing water bodies such as rivers, streams etc. Photograph 1.3: Aquatic Ecosystem  Ecosystem 5 Whereas standing water bodies such as lakes, ponds, pools, bogs, and other reservoirs are known as lentic ecosystem. Photograph 1.4: Lentic Ecosystem (Left) and Lotic Ecosystem (Right) Lentic Ecosystem Lentic ecosystem refers to all standing water bodies. Lakes and ponds are the main examples of Lentic Ecosystem. The word lentic (from latin word lentus meaning slow or motionless) mainly refers to stationary or relatively still water. These ecosystems are home for algae, crabs, shrimps, amphibians such as frogs and salamanders, for both rooted and floating leaved plants and reptiles including alligators and other water snakes. Lotic Ecosystem They mainly refer to the rapidly flowing water bodies which moves in a unidirectional way such as rivers and streams. The word lotic (from latin word lotus meaning washing) mainly refers to flowing water. These ecosystems harbour numerous species of insects such as beetles, mayflies, stoneflies and several species of fishes including trout, Eels, minnow, etc. Apart from these aquatic species, these ecosystems also include various mammals such as beavers, river dolphins and otters. Marine ecosystem: Marine ecosystems can be defined as the interaction of plants, animals, and the marine environment. The term “marine ecosystem” encompasses the salty waters of the earth, and is also known simply as a salt water ecosystem. It includes seas and oceans. Marine ecosystems have more salt content and greater biodiversity in comparison to the freshwater ecosystems. It covers the largest surface area of the earth. Two third of earth is covered by water and they include oceans, seas, intertidal zone, reefs, seabed, hydrothermal vents and rock pools. As the marine ecosystem is more concentrated with salts it makes difficult for freshwater organisms to live in. Similarly, marine animals cannot survive in freshwater. Their body is adapted to live in saltwater; if they are placed in less salty water, their body may swell. Marine ecosystem can be classified mainly into following two categories: Ocean ecosystem Coastal ecosystem Ocean ecosystem Our planet, earth is gifted with the five major oceans, namely Pacific, Indian, Arctic, Antarctic and the Atlantic Ocean. Among all these five oceans, the Pacific and the Atlantic are the largest and deepest 6 Environmental Science ocean. These oceans serve as a home to many aquatic species. Few creatures of these ecosystems include shellfish, shark, tube worms, crab, small and large ocean fishes, turtles, crustaceans, blue whale, reptiles, marine mammals, seabirds, plankton, corals and other ocean plants. Coastal ecosystem Coastal ecosystem comprises of open systems of land and water which are joined together to form the coastal ecosystems. The coastal ecosystems have a different kind of structure, and diversity. A wide variety of species of aquatic plants and algae are found at the bottom of the coastal ecosystem. The fauna is also found in coastal region and it mainly consists of crabs, fish, insects, lobsters, snails, shrimps, etc. 1.2.1.2 Terrestrial ecosystem Terrestrial ecosystems are exclusively land-based ecosystems. It comprises a community of organism and their environment that occurs on the land masses of earth surface. Terrestrial ecosystem occupies about 28% of the earth surface. Terrestrial ecosystem is different from aquatic ecosystem with lower water availability. There are different types of terrestrial ecosystems distributed around various geological zones. They are as follows: Forest Ecosystem Grassland Ecosystem Tundra Ecosystem Desert Ecosystem Forest Ecosystem A forest ecosystem consists of various types of microorganisms, plants and animals and all these components live in coordination with each other. Forests help in maintaining the temperature of the earth and plays a major role in carbon sink. They are of great importance in maintaining the ecological balances. Grassland Ecosystem The grassland ecosystem is dominated by grasses and herbs. It occupies about 19% of the earth surface and usually occurs in the interior parts of the continent. Temperate grasslands and savanna grasslands are some of the examples of grassland ecosystems. Tundra Ecosystem Tundra is known for large stretches of bare ground and rock. Tundra ecosystems are devoid of trees and it is also known for patchy mantles of low vegetation such as mosses, lichens, herbs and small shrubs. These ecosystems are found in cold climates or where rainfall is in scarce. These are covered with snow for most of the year. The Arctic or mountain tops are the examples of tundra type ecosystem. Desert Ecosystem Deserts are found throughout the world. It covers about 14 percent of the earth surface. These ecosystems are usually covered with cloudless sky and therefore, the sun radiation heats up the desert quickly, resulting in the highest air temperature on the earth. Sky In contrast, nights are very cold as the temperature goes down fast due to loss of heat into the atmosphere through radiation. These are the regions with very little rainfall and thus produces sparse perennial vegetation of widely spaced shrubs.  Ecosystem 7 Photograph 1.5: Terrestrial Ecosystem 1.2.2 Artificial ecosystems Ecosystems that are made and maintained by man is called artificial ecosystem. These ecosystems are made and modified for commercial or other benefits. These can either be aquatic or terrestrial type. Few examples may include park, dam, garden etc. The zoos, aquariums and botanical gardens are examples of artificial ecosystems which are maintained with the aim of conserving biodiversity. In this ecosystem, the plants and animals are placed in well-protected areas similar to their natural habitats and requirements. 1.3 STRUCTURE OF ECOSYSTEM The structure of an ecosystem describes the organisms and physical features of the environment includ- ing the amount and distribution of nutrients in a particular habitat. It also provides information regard- ing the range of climatic conditions prevailing in the area. The various components of an ecosystem may be grouped into two main types: Biotic (living) components Abiotic (non-living) components 1.3.1 Biotic (living) components The term “biotic” is a combination of two terms, “bio” which means life and “ic” meaning like. Therefore the term means life-like and is related to all the living entities present in an ecosystem. Or in other words, the living organisms present in an ecosystem form the biotic component. Based on their mode of obtaining food, the organisms occurring in an ecosystem are classified into three categories: Producers (autotrophs) Consumers (heterotrophs) Decomposers (saprotrophs) 8 Environmental Science 1.3.1.1 Producers (autotrophs) These include all green plants, blue green algae, some bacteria and free-floating autotrophic micro- organisms called phytoplankton. All these organisms possess photosynthetic pigments (e.g. chlorophyll) and can generate their own energy requirement (food) through photosynthesis in presence of sunlight and chlorophyll. As green plants, blue green algae etc. prepare their food for themselves with the help of sunlight, they are known as photo autotrophs or simply autotrophs (i.e. auto = self, trophos = feeder). 1.3.1.2 Consumers (heterotrophs) These are mainly the animals. They are unable to synthesize food for themselves. Therefore, they are dependent on the consumers for their food & utilise materials and energy stored by them. They are also known as heterotrophs (i.e. hetros = others, trophos = feeder). The consumers are of four types: Primary or first order consumers or herbivores: These are the animals which feed on plants or producers. Cattle, deer, goat, rabbit, rats, grasshoppers etc. are the common herbivores in terrestrial ecosystem and snails, mosquito, tadpoles etc. are the common herbivores in the aquatic ecosystem. Secondary or second order consumers or primary carnivores: The animals which feed on the herbivores are called the pri¬mary carnivores or secondary consumers. Examples: cats, foxes, snakes etc. are secondary consumers in the terrestrial ecosystem and water bugs, water beetles, frogs, small fish etc. are secondary consumers in the aquatic ecosystem. Tertiary or third order consumers: These are the large carnivores which feed on the secondary consumers. Common examples include large fish, water birds etc. in aquatic ecosystems, and wolves, snake etc. in terrestrial ecosystems. Quaternary Consumers or Fourth Order Consumers or Omnivores: These are the largest carnivores which feed on the tertiary consumers and are not eaten up by any other animal. Lions, tigers, eagle etc. are the examples in land ecosystems and shark, crocodiles etc. are the examples in aquatic ecosystems. Tree Bacteria BEE Photograph 1.6: Biotic Components  Ecosystem 9 1.3.1.3 Decomposers or reducers (saprotrophs) Bacteria and fungi belong to this category. They breakdown the dead organic materials of producers (plants) and consumers (animals) for their food. During metabolism process, they release simple inorganic and organic substances as by-products to the environment. These simple substances are reused by the producers resulting in a cyclic exchange of materials between the biotic organism and the abiotic environment of the ecosystem. The decomposers are known as Saprotrophs (i.e., sapros = rotten, trophos = feeder). 1.3.2 Abiotic (non-living) components The non-living factors or the physical environment prevailing in an ecosystem form the abiotic components. They have a strong influence on the structure, distribution, behaviour and inter-relationship of organisms. Abiotic components include: Inorganic substances Organic compounds Climatic factors Bacteria Fungi Air Salinity Soil Plants Archea Temperature Light Water Animals Protists Minerals pH Humidity Photograph 1.7: Biotic and Abiotic Components 1.3.2.1 Inorganic substances Inorganic substances such as carbon, nitrogen, oxygen, calcium, phosphorus etc. and their compounds (water, carbon dioxide etc.) constitute the main abiotic component. These occur either in the form of compounds dissolved in water, in the soil or in the air. 1.3.2.2 Organic substances These include carbohydrates, proteins, lipids etc. These are present in living organism and dead organic matter. The dead organic matter is broken down by the action of decomposers (e.g. bacteria, fungi) into inorganic substances for their recycling. 10 Environmental Science 1.3.2.3 Climatic factors These include light, temperature, humidity, wind, rainfall. Water etc. and also edaphic factors such as soil, substrate, topography, minerals etc. 1.4 FOOD CHAIN AND FOOD WEB For survival in eco-system and to get energy one must eat. Food chain and food web show who eats whom & describe the transfer of energy within an ecosystem, from one organism to another. Infect, food chain and food web are the schematic representation of feeding relationship among the various organisms. 1.4.1 Food Chain The food we eat provide us energy to carry out our day-to-day activity. It is applicable for all other living organism. In ecosystem, all living organisms are interconnected with each other in a systematic chain with respect to their mode of manufacturing food and with their feeding habits. The interactions among various components of the ecosystem involves flow of energy from one component to other component. Food chains regulate and maintain the population size of different animals, thereby maintaining the ecological balance on earth. Let’s take an example of a grassland ecosystem, wherein all green plants (e.g. herbs, shrubs, trees etc.) are producers or autotrophs and they are eaten up by primary consumers i.e. herbivores (e.g. cattle, deer, goat, rabbit, rats, grasshoppers etc.). The herbivores are subsequently eaten up by secondary consumers i.e. primary carnivores (e.g. cats, foxes, snakes etc.). The primary carnivores are eaten up by tertiary consumers i.e. larger carnivores (e.g. Wolves, large fish etc.). Finally, the tertiary consumers are eaten up by quaternary consumers i.e. omnivores. Therefore, it can be seen that beginning with the producers, onward to herbivores, carnivores and next level carnivores, all organism are inter-linked in a definite sequential chain and involve in transfer of energy from the producers onward to the last link in the chain. Therefore, the food chain may be defined as the sequential inter-linking of organisms involving transfer of food energy from the producers, through a series of organism to the last link in the chain i.e.; referred to Omnivores. 1.4.1.1 Length of Food Chain: The distinct sequential steps in the food chain is the transfer of energy occurs at different trophic levels. For example, green plants (producers), form the first trophic level – the producer level; the plant eaters (herbivores), also called primary consumers, belong to second trophic level– the primary consumer level; and the flesh eaters (carnivores), also called secondary consumer, represents the third trophic level – the secondary consumer level and so on. In ecosystem, different food chains may have two, three or four or maximum five trophic levels. A food chain may end at the (i) herbivore (primary consumer) level, (ii) primary carnivore (secondary consumer) level, (iii) secondary carnivore (tertiary consumer) level or (iv) tertiary carnivore (quaternary) level. 1.4.1.2 Characteristics of Food Chain 1. A food chain involves transfer of food energy between the living organisms (biotic components) of an ecosystem. In a food chain, repeated eating occurs i.e. each group eats the other group and subsequently eaten by some other group of the organism. 2. In a food chain, flow of energy is unidirectional from sun to producers and subsequently to series of different types of consumers.  Ecosystem 11 Photograph 1.8: Food Chain 3. Usually, there are 3 to 4 trophic levels in a food chain. In few cases there may be maximum of 5 trophic levels. 4. Omnivores organisms may occupy different trophic positions in different food chain. 1.4.2 Food Web Food web is a network of food chains which are interconnected at various trophic levels so as to form a number of feeding junctions amongst different organisms of a biotic community. In nature, food chain do not operate in isolation as because in natural environment, each organism is gen- erally eaten by two or more kinds of organism which, intern are eaten by several other organism. Thus, instead of straight line food chain, the relationship among organisms forms an in- terlinking pattern called a food web. For example, plant may be eaten up by caterpillar, rat, goat etc. Grasshopper may be eaten away by frog, rat may be eaten away by cat, dear may be eaten away by tiger. A food web, thus, provides alternative pathways of food availability. If a particular species of producer is destroyed by a disease or any other reason in the ecosys- tem, the herbivores of that area can feed on other species of producers. Similarly, if some herbi- vore species is eliminated from the ecosystem, secondary consumers may feed on other species of available herbivores. Availability of the alternatives in a food web make the ecosystem more stable. Hence, the alternative food energy available in the nature form a sort of interlocking pattern called food web. In food webs, any given species may operate simultaneously at more than one tropic levels. 1.4.2.1 Characteristics of Food Web 1. Each food web is formed by interlinking of food chains and it is never straight, like food chain. 2. A food web provides alternative links of food availability. 3. Availability of more alternatives in the food web, make the ecosystem more stable. 4. Food webs help in development of ecosystem. 12 Environmental Science Photograph 1.9: Food Web 1.5 CARBON, NITROGEN, SULPHUR, PHOSPHORUS CYCLE Energy in the form of sunlight enters into our eco-system, flows through it and leaving in the form of heat in the atmosphere. However, there are six most common element in the form of Carbon, Nitrogen, Sulphur, Phosphorus, Hydrogen and Oxygen which get recycled by taking variety of chemical forms. All these elements are very much important for the survival of living organisms in the eco-system. By recycling processes, they remain stored for long or short duration in the atmosphere, on land, in water or beneath the earth’s surface as well as in the bodies of living organism. 1.5.1 Carbon cycle Carbon is an essential element for all life forms on earth. Whether these life forms, take carbon to help produce food or release carbon as part of respiration, the intake and output of carbon is a component of all plant and animal life. Carbon is economically important to human life, in the form of fossil fuels. Carbon is in a constant state of movement from one place to another through different processes such as photosynthesis, burning fossil fuels and simply releasing breath from lungs. The movement of carbon through these processes is known as carbon cycle. Following are the major steps involved in the carbon cycle process: Carbon present in the atmosphere is used by plants to build leaves and stems. These plants are then digested by animals and carbon gets accumulated into their bodies. These animals and plants eventually die, and upon decomposing, carbon is released back into the atmosphere and stored in the form of gasses such as carbon dioxide. Some of the carbon that is not released back into the atmosphere eventually become fossil fuel. These fossil fuels are then used for man-made activities, resulting in more carbon emission to the atmosphere in the form of carbon dioxide.  Ecosystem 13 The carbon cycle is vital to life on Earth. Nature tends to keep carbon levels balanced, it means that the amount of carbon produced naturally is equal to the amount of carbon absorbed naturally. Maintaining this carbon balance allows the planet to remain hospitable for life. Scientists believe that humans have upset this balance by burning fossil fuels, which has added more carbon to the atmosphere than usual and led to climate change and global warming. Photograph 1.10: Carbon Cycle 1.5.2 Nitrogen Cycle Nitrogen, or N (scientific abbreviation), is a colourless, odourless element. Nitrogen is present all around us. It is in the soil under our feet, in the water we drink, and in the air we breathe. Nitrogen is important to all living things, including us. It plays a key role in plant growth. Nitrogen is an essential component of DNA, RNA and proteins, the building blocks of life. All organisms require nitrogen to live and grow. Forms of Nitrogen: (a) Organic forms: Ammonium (NH4), Nitrite (NO2), Nitrate (NO3), Nitrous oxide (N2O) and Nitric oxide (NO). (b) Inorganic form: Nitrogen gas (N2). The nitrogen cycle includes movement of nitrogen through both living and non-living things. It moves through the atmosphere, soil, water, plants, animals and bacteria. In order to move through the different parts of the cycle, nitrogen need to change its forms. In the atmosphere, nitrogen exists as a gas (N2), but in the soils it exists as nitrogen oxide (NO) and nitrogen dioxide (NO2). It is used as a fertilizer in other forms, such as ammonia (NH3) and ammonium nitrate (NH4NO3). There are five stages in the nitrogen cycle which include: Nitrogen fixation Nitrogen assimilation Ammonification 14 Environmental Science Nitrification Denitrification. Stage 1: Nitrogen Fixation Nitrogen is the most abundant element in Earth’s atmosphere and approximately 78% of the atmosphere is nitrogen. But plants and other living organisms are not able to use nitrogen in its gaseous form. For nitrogen to be available in the usable form for plant and other living organisms, it must be converted into different chemical forms. The process of converting nitrogen into biologically available nitrogen (organic matter) is called nitrogen fixation. A small amount of nitrogen can be fixed when lightning provides the energy needed for nitrogen to react with oxygen, producing nitrogen oxide (NO) and nitrogen dioxide (NO2). These forms of nitrogen then enter soils through rain or snow. Nitrogen can also be fixed through the industrial process that manufactures fertilizer. This form of fixing occurs under high heat and pressure, during which atmospheric nitrogen and hydrogen are combined to form ammonia (NH3), which may then be processed further, to produce ammonium nitrate (NH4NO3), a form of nitrogen that can be added to soils and used by plants. Most nitrogen fixation occurs naturally, in the soil, by bacteria. Stage 2: Ammonification It is the process of releasing ammonia by certain microorganisms utilising organic compounds derived from the dead organic remains of plants and animals and excrete of animals. The microorganisms specially involved are actinomycetes and bacilli. Photograph 1.11: Nitrogen Cycle  Ecosystem 15 Stage 3: Nitrification In nitrification process the ammonia is converted into compounds called nitrites (NO2) and nitrates (NO3). These nitrates are used by plants and also animals that consume the plants. Although nitrite is not usable by plants and animals directly, other bacteria can change nitrites into nitrates, a form that is usable by plants and animals. Nitrification requires the presence of oxygen, so nitrification can happen only in oxygen rich environment like circulation of flowing water and the surface layers of soil and sediments. The process of nitrification is important to plants, as it produces an extra stash of available nitrogen that can be absorbed by the plants through their root systems. Stage 4: Nitrogen Assimilation In this process inorganic nitrogen in the form of nitrates, nitrites and ammonia is absorbed by the green plants via their roots and then it is converted into nitrogenous organic compounds. Nitrates are first converted into ammonia which combines with organic acids to form amino acids. Amino acids are used in the synthesis of proteins, enzymes, chlorophylls, nucleic acids etc. Stage 5: Denitrification In the fifth stage of the nitrogen cycle, nitrogen returns to the air as nitrates and are converted to atmospheric nitrogen (N2) by bacteria through the process called denitrification. This results in an overall loss of nitrogen from soils, as the gaseous form of nitrogen moves into the atmosphere, back where we began our story. 1.5.3 Sulphur Cycle Sulphur is associated with the foods having high rich protein such as dairy products, eggs, fish, meat and sea food. Sulphur helps to make cell rigid and strong that are found in the hair, nails and skin. Sulphur in plants help to form important enzymes and assist in the formation of plant proteins. Fertilizers, pesticides and manure are the primary source of sulphur for plant. Sulphur cycle describes the movement of sulphur through ocean, land and atmosphere. The sulphur cycle is explained below: In atmosphere sulphur is found in the form of sulphur dioxide (SO2) and enters in three ways, from (i) decomposition of organic molecules, (ii) volcanic and geothermal vents and (iii) burning of fossil fuels by humans. Sulphur is deposited on land in four major ways namely, precipitation, direct fallout from the atmosphere, rock weathering and geothermal vents. Sulphur enters the ocean via runoff from land, from atmospheric fallout and from under water geothermal vents. In atmosphere, sulphur comes in contact with the air and is converted into sulphates. These sulphates are consumed by plants and microbes and are converted into organic forms. Converted organic forms of sulphur is then consumed by animals and thus sulphur moves in the food chain. When animals die, some of the sulphur is released to the atmosphere by their decomposition, thus a sulphur cycle gets completed. Remaining sulphur enters into the tissues of microbes. 16 Environmental Science Photograph 1.12: Sulphur Cycle 1.5.4 Phosphorus Cycle Phosphorus is an essential nutrient for all living organisms like animals and plants. It plays a critical role in cell development and is a key component of molecules that store energy, such as ATP, DNA and lipids (fates and oil). Insufficient phosphorus in the soil may result in the poor crop yield. Since phosphorus and phosphorus containing compounds are present only on land, atmosphere plays no significant role in the phosphorus cycle. Phosphorus cycle is a very slow process which involves three key steps as mentioned below: Weathering Absorption by plant and animal Return to the environment via decomposition Weathering Since the main source of phosphorus is found in rocks, the first step of phosphorus cycle involves extraction of phosphorus as phosphate salts from the rocks by weathering. These salts are washed away into the ground and get mixed in the soil. Absorption by plants and animals Plants, fungi and microorganisms are able to absorb phosphate salts, dissolved in water and grow. Phosphorus can also be washed into the water systems and plant can also directly absorb phosphorus from the water and grow. In addition to plants, animals also get phosphorus from drinking water and eating plants. However, the amount of phosphorus present in the soil is very less and therefore, farmers apply phosphate fertilizer on agricultural land.  Ecosystem 17 Return to the environment via decomposition When the plants and animals die they are decomposed by microorganisms. In this process, the organic form of phosphorus is converted into the inorganic form and return back to the environment via soil or water. Plants and animals can then use this phosphorus, and step 2 of the cycle is repeated. Soil and water also end up in formation of sediments and rocks, which again releases phosphorus by weathering. Hence, phosphorus cycle gets repeated. Photograph 1.13: Phosphorus Cycle 1.6 GLOBAL WARMING Our earth is surrounded by atmosphere which comprises of clouds, dust particles, gases (carbon dioxide, methane, nitrous oxide etc.) and water vapours. These elements, present in the atmosphere, filter and scatter large quantity of solar radiation falling on the earth. Only about 48% of the solar radiation reaches the surface of the earth and only 1% of it is absorbed by the plants. The solar radiation falling on earth surface is reflected back as infra-red radiations into the atmosphere. Part of the infra-red radiations pass through the atmosphere. Most of the remaining infra-red radiations are absorbed by the gasses present in the atmosphere and re-emitted in all directions. These re-emitted infra-red radiations, keep the earth surface warm and the mean annual temperature at150C. Had these re-emitted infra-red radiations not been there, the average temperature on the earth would have been (-)200C, almost same as that of the moon which lacks atmosphere. Warming of earth surface and troposphere caused by the presence of water vapour, carbon dioxide (CO2), methane (CH4), chlorofluorocarbons (CFCs) and nitrous oxide (N2O) in the atmosphere is called Greenhouse Effect. These gases are called greenhouse gasses. Global warming is a term used for the rise in the average temperature of the earth’s climatic system and its related effects. Global warming is caused by increasing concentration of greenhouse gasses and other human caused emissions. Increasing or decreasing amount of greenhouse gasses within the atmosphere act to either hold in or release more of the heat from the sun. 18 Environmental Science The global annual temperature has increased in total by a little more than 1 degree Celsius, between 1880 to 1980. For the last 40 years, we have seen the global annual temperature rise by 0.18 degree Celsius per decade. Now the climate scientist have concluded that we must limit global warming to 1.5 degree Celsius by 2040 to avoid most devastating effects: the extreme droughts, wildfires, floods, tropical storm and other disasters that we refer to collectively as climate change. Man is adding large amount of carbon dioxide (CO2) to the atmosphere every year by burning fossil fuels in homes, industries and automobiles, biomass burning associated with agricultural practices etc. Methane is added to the atmosphere by paddy fields, cattle shades, biogas plant etc. Similarly, chlorofluorocarbons are emitted into the atmosphere by refrigerators, and air conditioners. Nitrous oxide is produced from organic matter and fertilizers by bacteria as well as from automobile exhaust and industries. Thus, increasing amount of greenhouse gasses, consequently resulting in the rise in the global temperature. 1.6.1 Ozone Depletion Ozone is a tri-atomic molecule made up of three atoms of oxygen, O3. Very little quantity of ozone is present in the lower part of atmosphere, called troposphere. However, good amount of ozone is present in the upper part of atmosphere, called stratosphere which is about 18-50 km above the equator. Its maximum concentration is at 23-25 km above equator. This rich zone of ozone in the stratosphere is called ozone layer or ozonosphere. The ozone layer act as a shield for life on earth and it is commonly called ozone shield as this region intercepts high energy ultraviolet (UV) radiations and allows low energy UV radiations to reach the earth’s surface. The thinning of ozone layer is commonly called ozone depletion. Air pollutants and chlorofluorocarbons (CFCs) are mainly responsible for depletion of ozone layer in stratosphere. In addition to this, methane (CH4) and oxides of nitrogen (NOx) also contribute in thinning of ozone layer. Chlorofluorocarbons (CFCs) are synthetic, harmful chemicals, widely used in fire extinguishers, in air conditioners as coolants; in aerosol sprayers and as propellants. Once released in the air, these harmful chemicals produce ‘active chlorine’ (CI and CIO radicals) in the presence of UV radiations. These radicals through chain reactions, then destroy the ozone by converting it into oxygen. Due to this, the ozone layer in the upper atmosphere (i.e. stratosphere) becomes thinner. You will be surprised to know that a single ‘active chlorine’ converts one lakh molecules of ozone into oxygen. Amount of atmospheric ozone is measured by Dobson spectrometer and is expressed in Dobson units (DU). 1.6.1.1 Ozone Depleting Substances (ODS) These are the substances which react with the ozone layer in the stratosphere and destroy it. The main ODS are Chlorofluorocarbons, methane, nitrous oxide, carbon tetrachloride and chlorine. Out of these, Chlorofluorocarbons are the principal ODS. 1.6.1.2 Effect of Ozone Depletion The thinning of ozone layer allows more UV radiations to pass through and strike the earth. These causes harmful effects on man, animals and plants such as skin cancer, herpes, dimming of eye sight, cataract in eyes, lowering the immune system, increased embryos in the mother’s uterus, global warming etc.  Ecosystem 19 1.7 UNIT SUMMARY 1. All living organism interact with each other and also with non-living physical surroundings to maintain a balance in nature. All these interacting organisms, along with non-living physical surroundings form an ecosystem. 2. The various components of any ecosystem may be grouped into two main types: (i) Biotic component (living) (ii) Abiotic (non-living) component 3. Biotic component includes (i) producers (ii) consumers and (iii) decomposers. Abiotic component includes (i) inorganic substances (ii) organic compounds and (iii) climatic factors. 4. All green plants, blue green algae, some bacteria and free-floating autotrophic micro-organisms called phytoplankton comes under the category of producers. Consumers are mainly the animals. Decomposers include bacteria and fungi of decay. 5. In an ecosystem, all living organisms are linked in a systematic chain with respect to their mode of manufacturing food/feeding habits. 6. Food chains are always straight and there is unidirectional flow of energy from sun to producers and subsequently to different types of consumers. 7. Food web is a network of food chains which are interconnected at various trophic levels so as to form a number of feeding connections among living organisms. 8. Carbon is an essential element for all life forms on earth. 9. Carbon is in a constant state of movement from one place to another through different processes such as photosynthesis, burning fossil fuels and simply releasing breath from lungs. The movement of carbon through these processes is known as carbon cycle. 10. Nitrogen, or N (scientific abbreviation), is a colourless, odourless element. Nitrogen is present all round us. 11. Nitrogen is in the soil under our feet, in the water we drink, and in the air we breathe. Nitrogen is important to all living things, including us. 12. The nitrogen cycle includes movement of nitrogen through both living and non-living things. 13. There are five stages in the nitrogen cycle which include: Nitrogen fixation, Nitrogen assimilation, Ammonification, Nitrification, Denitrification. 14. Sulphur is associated with foods having high rich protein such as dairy products, eggs, fish, meat and sea food. 15. Sulphur cycle describes the movement of sulphur through ocean, land and atmosphere. 16. Phosphorus is an essential nutrient for all living organisms like animals and plants. 17. Phosphorus cycle is a very slow process which involves three key steps namely, Weathering, Absorption by plant and animal, Return to the environment via decomposition. 18. The gases in the atmosphere, most responsible for keeping the earth’s surface warm, are carbon dioxide (CO2), methane (CH4), chlorofluorocarbons (CFCs) and nitrous oxide (N2O). These gases are called greenhouse gasses. 19. Global warming is a term used for the rise in the average temperature of the earth’s climatic system and its related effects. 20. For the last 40 years, we have seen the global annual temperature rise by 0.18 degree Celsius per decade. 20 Environmental Science 21. The gases in the atmosphere, most responsible for keeping the earth’s surface warm, are carbon dioxide (CO2), methane (CH4), chlorofluorocarbons (CFCs) and nitrous oxide (N2O). These gases are called greenhouse gasses. 22. This rich zone of ozone in the stratosphere is called ozone layer or ozonosphere. The ozone layer act as a shield for life on earth. 23. The thinning of ozone layer is commonly called ozone depletion. 24. Air pollutants and chlorofluorocarbons (CFCs) are mainly responsible for depletion of ozone layer in stratosphere. 25. The thinning of ozone layer allows more UV radiations to pass through and strike the earth. These causes harmful effects on man, animals and plants. 1.8 INTERESTING FACTS 1. Tropical rainforests are found near the equator wherein the weather always remains in warm and wet condition. Such climatic conditions are the key ingredients for making lots of lush plants and trees. Half of the world’s plants and animals live in the tropical rainforests. It’s a very busy ecosystem with many kinds of plants, animals, fungi, and microscopic organisms. 2. In most of the deserts, there is very little rain. Most of the time the land remains in dry condition. Here, living organisms have creative ways of finding and saving water. Cactuses are very good at storing water. They can live without rain for months. The kangaroo mouse, lives in Nevada desert, rarely drinks water. They get water from the food they eat. 3. There are freshwater ecosystems all over the world. They are home to some amazing creatures. There are many kinds of frogs, fish, insects, and microscopic organisms like amoebas. And there are rare species like river dolphins in Asia and South America, otters in North America, beavers in North America and Europe, and platypuses in Australia. 4. Almost all tundra is located in the Arctic in the Northern Hemisphere. Tundra is a vast and treeless land. It covers about 20% of Earth’s surface. The ground is often permanently frozen therefore trees can’t grow here. In the Arctic tundra, there are polar bears, foxes, and reindeer. 5. At the bottom of the ocean, there are small underwater volcanoes spew scalding hot water, gases, and chemicals like methane and ammonia. They’re called hydrothermal vents. It’s a dark place to live, but some animals such as Giant tube worms over 6 feet (1.8 meters) long, clams, and shrimp lives here. The tube worms have bacteria inside them that make food out of the methane and ammonia from the vents.  Ecosystem 21 1.9 INNOVATIVE ACTIVITIES 1. Seminar: A topic may be divided into sub-topics among 8 to10 students for presentation. 2. Symposium: Paper presentation by students on the topic of their choice. 3. Group discussion: In a group of 10 students with one group leader, one moderator and one recorder. Group leader to ensure participation by all students, moderator to ensure no cross talks and recorder to record the observations including his/her own. 4. Project work: Project work on a suitable topic may be assigned to a group of 3 to 4 students. Project may be experimental or investigation type. 1.10 EXERCISES A- Subjective Questions 1. Who introduced the term ecosystem and when? 2. Explain the structure of ecosystem with flow chart. 3. Define producers, consumers and decomposers. 4. (a) Give two examples of decomposers present in ecosystem. (b) How is the presence of decomposers crucial in the ecosystem? 5. Define omnivores with examples. 6. Give reasons for the following: (a) Food chain consists of 4 or maximum 5 chains (b) In the stratosphere, ozone shield normally has steady concentration of ozone. 7. Explain ozone layer and its importance. How it is being affected? 8. How man’s activities are adding carbon dioxide to the atmosphere? 9. Explain carbon cycle and its importance. 10. Describe component of nitrogen cycle. B- Objective Questions 1. Which of the following is not the scope of Environment? (a) Hydrosphere (b) Lithosphere (c) Biosphere (d) Satellite sphere 2. Which the main reasons for acid rain? (a) Global Warming (b) Reduction in Global warming (c) C F C gases (d) Human Rehabilitation 3. Food chain consists of (a) Carnivorous (b) Producer (c) Herbivorous (d) All the above 4. Which gas is responsible for depletion of Ozone layer? (a) Carbon dioxide (b) Oxygen (c) Sulphur (d) Nitrogen 5. Air is a mixture of various gases. One of the gases is 21% part of the air and is essential for the survival of human beings. This gas is (a) Nitrogen (b) Ozone (c) Oxygen (d) Argon 6. This factor contributes to the carbon cycle (a) Fossil fuel combustion (b) Respiration (c) Photosynthesis (d) Nitrification 22 Environmental Science 7. The source of carbon to plants in the carbon cycle is (a) Fossil fuels (b) Carbonate rocks (c) Atmospheric carbon dioxide (d) Atmospheric sulphur 8. Nitrification is a part of which of the following cycle? (a) Oxygen (b) Nitrogen (c) Phosphorus (d) Sulphur 9. Which is the main reason for depletion of ozone layer? (a) Urbanization (b) Industrialization (c) Excessive use of CFC (d) Global warming 10. In phosphorus cycle, phosphate becomes available by weathering of rocks first to (a) Consumers (b) Producers (c) Decomposers (d) None of these Answer Key 1 (d), 2 (c), 3 (d), 4 (a), 5 (c), 6 (a), 7 (c), 8 (b), 9 (c), 10 (a) 1.11 SUGGESTED LEARNING RESOURCES (a) Reference Books Suresh K. Dhameja, Environmental Studies, S.K. Kataria & Sons, 2012. Surinder Deswal, Energy, Environment Ecology and Society, Dhanpat Rai & Sons, 2014. P.K. Pandey, Environment and Ecology, Sun India Publication, 2009. P.S. Ramakrishnan, Energy and Sustainable Development, National Book Trust, 2014. M.K. Goyal, Our Environment (Hindi text book), Agrawal Publication, Agra, 2013. C.N.R. Rao, Understanding Chemistry, University press (India) Pvt. Ltd., 2011. G.Chopra, Science Biology, Pradeep Publications, New Delhi - 2016 (b) Open source software and website www.nptel.ac.in https://swayam.gov.in www.cpcp.gov.in www. indiaenvironmentportal.org.in Photographs: Courtesy Creative common (C) Video resources Ecosystem Biogeochemi- Global cal cycles Warming  Air and Noise Pollution 23 2 Air and Noise Pollution UNIT SPECIFICS This unit deals with the following main aspects: Definition of pollution and pollutant, Natural and manmade sources of air pollution. Air Pollutants: Types, Particulate Pollutants: effects and control.  Gaseous Pollution Control: Absorber, Catalytic Converter, Effects of air pollution due to Refrigerants, I.C., Boiler.  Noise pollution: sources of pollution, measurement of pollution level, Effects of Noise pollution, Noise pollution (Regulation and Control) Rules, 2000. All the topics are well supported with relevant photographs for generating further curiosity and creativity. A number of multiple choice as well as subjective type questions are given so that one can go through them for practice. Learning resources like reference books, open resource software & website, video resources etc. are also given in the unit for further clarifications of concepts and doubts. It may also be noted that for getting more information on various topics of interest, some QR codes have been provided in different sections which can be scanned for relevant supportive knowledge. RATIONALE Air pollution and excessive noise harm our health and also our environment. Air pollution can mainly cause cardiovascular and respiratory related diseases. It is the leading environmental cause of premature death in many developed and developing countries. Air pollution also has negative impacts on the quality of water and soil. It damages ecosystems through eutrophication (excess nitrogen pollution) and acid rain. Hence, agriculture, forests, buildings etc. are also affected due to air pollution. Air pollution has many sources such as industry, transport, energy production, agriculture etc. In addition to the air pollution, noise pollution also effects our health. Environmental noise levels are rising in urban areas, mainly due to increasing traffic volumes, intensifying industrial and recreational activities. This can lead to increased stress level, sleep disturbance and may adversely affect health and quality of life. Noise also has an impact on wildlife. This unit aims at introducing basic concepts of air and noise pollution with an emphasis on its effect on our health and environment. The unit include types of air pollutants, its effects 24 Environmental Science and control, source of noise pollution, its measurement and effects. After completion of this unit, the students will develop basic concepts of air and noise pollution. The students will also know the pollution control mechanism which will give them an opportunity to protect our health and environment by minimising the air and noise pollution. PRE-REQUISITES High School Chemistry UNIT OUTCOMES Students will be able to: U2-O1: Explain environmental pollution and its sources. U2-O2: Explain various types of air pollutants, its effect and control mechanism. U2-O3: Describe various types of gaseous pollution control mechanism. U2-O4: Identify sources of noise pollution and its effect. U2-O5: Explain Noise pollution rules, 2000. MAPPING OF UNIT OUTCOMES WITH THE COURSE OUTCOMES EXPECTED MAPPING WITH COURSE OUTCOMES Unit-1 (1-Weak Correlation; 2-Medium correlation; 3-Strong Correlation) Outcome CO-1 CO-2 CO-3 CO-4 CO-5 U2-O1 - 3 - - - U2-O2 - 3 2 - - U2-O3 - - 3 - - U2-O4 - 3 - - - U2-O5 - 1 3 - - UNIT OVERVIEW 2.1 Introduction 2.2 Definition of pollution and pollutant, Natural and manmade sources of air pollution (Refrigerants, I.C. Boiler). 2.3 Air Pollutants: Types, Particulate Pollutants: effects and control (Bag filter, Cyclone separators, Electrostatic Precipitators). 2.4 Gaseous Pollution Control: Absorber, Catalytic Converter, Effects of air pollution due to Refrigerants, I.C., Boiler. 2.5 Noise pollution: sources of pollution, measurement of pollution level, Effects of Noise pollution, Noise pollution (Regulation and Control) Rules, 2000.  Air and Noise Pollution 25 2.6 Unit Summary 2.7 Innovative Activities 2.8 Interesting Facts 2.9 Exercises 2.10 Suggested Learning Resources 2.1 INTRODUCTION “We still have too much air and water pollution and we still need to work to reduce it. But we also need to put the problem of pollution into a historical as well as scientific perspective”. Ronald Reagan, Ex-president of United States of America The air is composed of 78% nitrogen, 21% oxygen, and 0.9% argon. The remaining elements include carbon dioxide, water vapour, hydrogen, and other trace elements. The atmosphere is a delicate balance of elements and particles. Air pollution occurs when there is an alteration to the composition of air. The main sources of air pollution are transportation, factory emissions, biomass consumption, agriculture production etc. The air pollution is caused due to excessive concentration of suspended particulate matter (SPM), carbon dioxide, nitrogen oxide in the atmosphere emitted from the sources that burns fuel. Air pollution including noise pollution is a significant risk factor for human health conditions, causing allergies, respiratory and cardiovascular disease as well as lung damage. It is also a major contributors to global warming and climate change. 2.2 DEFINITION OF POLLUTION AND POLLUTANT The word pollution come from Latin word “polluere” that means contamination. Hence in layman terms, the pollution is something that contaminates the environment. It may be defined as the presence of harmful substances in the air, water and soil which can have adverse effect on living beings and on Photograph 2.1: Types of Pollution 26 Environmental Science the environment. Due to pollution, undesirable changes occur in the physical, chemical or biological characteristics of air, water and soil that may be harmful for any living organism. Types of Pollution: There are mainly five types of pollution: Air Pollution    Water pollution Land pollution    Noise pollution Radioactive pollution Air Pollution Air pollution may be defined as the undesirable presence of one or more contaminants such as dust, fumes, gas, mist, odour, smoke, or vapour which are detrimental to human health in particular and the planet as a whole. Air pollution in many cases prevents photosynthesis process in plants which has serious consequences on the purification of air we breathe. It is a major contributor to global warming and climate change. Air pollution is indeed a significant risk factor for human health conditions, causing allergies, respiratory and cardiovascular diseases. Water Pollution Water pollution can be defined as the contamination of a stream, river, lake, ocean or any other water body, degrading water quality and rendering it toxic for the environment and human. The main causes of water pollution include sewage and waste water, urbanisation and deforestation, agriculture, industries, marine dumping and radioactive waste. Water pollution harms biodiversity and ecosystem. It has very negative impacts on human health. Many diseases such as diarrhea, cholera, typhoid, dysentery and skin infection result from drinking or being in contact with contaminated water. Land Pollution Land pollution refers to any physical or chemical changes in soil condition that may adversely affect the human health, plants and animals. Most soil pollutants are agricultural chemical, fertilisers and pesticides. Dumping of waste which may include municipal wastes, untreated sewage, industrial effluents etc. also pollutes the soil when harmful substances from dump leak into it. Noise Pollution Noise pollution can be defined as any unwanted or disturbing sound that effects the health and well- being of humans and other organism. Sound is measured in decibels. Sound that reaches 85 decibels or more is considered harmful for human ear. Noise pollution has its impact on millions of people on daily basis. The most common health problem in human is hearing loss. Exposure to loud noise may also cause high blood pressure, heart disease, sleep disturbances and stress. The main sources of noise pollution include traffic noise, air traffic noise, construction noise, catering and night life, animals etc. Radioactive Pollution Radioactive pollution is defined as increase in the natural radiation level in the environment caused mainly by human activities. The sources of radiation pollution involve any process that emanates radiation in the environment. Causes of radiation pollution include research and medical procedures and waste, nuclear power plants, TVs, computers, radio waves, cell phones, etc. However, the most common ones that can pose moderate to serious health risks are: Nuclear explosions and detonations of nuclear weapons, Defensive weapon production, Nuclear waste handling and disposal, Mining and Nuclear accidents.  Air and Noise Pollution 27 Photograph 2.2: Pollutants Pollutants Pollutants are the harmful substances which brings undesirable and harmful changes in the physical, chemical or biological characteristics of air, water and soil. Smoke from industries and automobiles, domestic and commercial sewage, radioactive substances from nuclear plants and discarded household articles (tins, bottles, broken crockery etc.) comes under the category of pollutants. Types of Pollutants: Pollutants can be categorised into following categories: Water Pollutants: The runoff from industries, agriculture fields and even from urban areas contribute largely to the water pollution. In addition, raw sewage is a major pollutant of water. Soil Pollutants: The main source of soil pollutant include municipal and industrial wastes, overdose of pesticides and herbicides etc. Air Pollutants: The major source of air pollutant is burning fossil fuels and it happens due to factory emission and automobiles. Also acid rain has adverse effect on forests and their inhabitants. Noise Pollutants: Major noise pollutant include horns of automobiles, loudspeakers, fire crackers, electrical appliances, traffic noise etc. Radioactive Pollutants: Radioactive pollutant include radiation released in nuclear power plant accidents, use of nuclear weapons, mining, spillage of radioactive chemicals, cosmic and other natural sources like gamma rays, radiation used for the treatment of diseases like cancer etc. Photograph 2.3: Sources of Air Pollution 28 Environmental Science 2.2.1 Natural and manmade sources of air pollution Air pollution may be caused by various processes and it may be natural or manmade (anthropogenic). Natural sources of air pollution It is caused due to continuous and temporary natural events and it cannot be prevented. Natural sources of air pollution are described below: Volcano Activities: Volcanic eruptions emit a series of toxic gases including sulphur and chlorine. It also emits particulate matter in the form of ash particles. Volcanic eruptions are restricted to localised area. Winds and Air Current: It can mobilise soil and other pollutants and spread it over the large areas. Wild Fires: It emit carbon monoxide and particulate matter into the atmosphere. It may affect significant areas although they can be restricted and contained to small area. Microbial Decaying Process: Microorganisms present in the environment have a major role in natural decaying processes of living organisms. This activity results in the natural release of gases especially methane gas and causes air pollution. Photograph 2.4: Natural Sources of Air Pollution Increasing Temperature: It contribute to an increase in the amounts of contaminants volatilizing from polluted soil and water into the air. Manmade sources of air pollution It is caused due to human activities and it has huge impact on environment and also on all of us. Manmade sources of air pollution are described below: Mining and Smelting: Crushing & processing of mineralogical deposits emits a variety of metals into the atmosphere and creates pollution. Foundry Activities: It emits a variety of metals into atmosphere due to processing of metallic raw materials (including the use of furnaces). Various Industrial Processes: These may emit both organic and inorganic contaminants through accidental spills and leaks of stored chemicals or mis-handling and storage of chemicals–especially inorganic chemicals of volatile nature. Transportation: Vehicles emits a series of air pollutants in the form of gases such as carbon monoxide, sulphur oxides, nitrogen oxides and particulate matter.  Air and Noise Pollution 29 Construction and Demolition Activities: These activities pollute the air with various constructionmaterials, specially demolition of old buildings which may contain a series of banned chemicals such as PCBs, PBDEs, Asbestos etc. Coal Power Plants: Burning of coal in coal power plant may emit a series of gases as well as particulate matter with metals (such as As, Pb, Hg) and organic compounds (especially PAHs). Waste Incineration: In this process, various toxic gases, and particulate matter is emitted into the atmosphere, depending on the composition of waste. Landfill Disposal Practices: Due to the natural microbial decaying activity in the disposal area methane gas is generated and pollute the environment. Agriculture: Agricultural activity pollute the air through emissions of ammonia gas and the application of pesticides/herbicides/insecticides which contain toxic volatile organic compounds. Defence Activities: These activities may pollute the air by emitting toxic gases through practices and training. Smoking: Smoking emits a series of toxic chemicals including a series of organic and inorganic chemicals, some of which may be carcinogenic also. Storage and Use of Household Products: House hold products such as paint, sprays, varnish, etc. that contains organic solvents which volatilize in the air and we feel smell while using them. Refrigerants: It is used in various electronic equipment such as refrigerator, air-conditioner etc. These are mainly responsible for creating greenhouse effect in the atmosphere, that warms the planet. Sources of Air Pollution 7% 8% 9% 45% 14% 17% Dust & Construction Waste Burning Transport Diesel generator Industries Domestic cooking Photograph 2.5: Manmade Sources of Air Pollution I.C. Boilers: These are combustion devices used to heat water or to produce steam. I.C. Boilers creates air pollution by emitting hazardous air pollutants in the atmosphere. 2.3 Air Pollutants “Air pollution is the excessive concentration of foreign matter in the air which adversely affects the well-being of the individual or cause damage to property”. - American Medical Association 30 Environmental Science The foreign matter which causes air pollution are called air pollutants. Air pollutants include gasses, liquid droplets and solid particles. They are classified according to the source of emission into two main groups: (i) Primary Pollutants and (ii) Secondary Pollutants. The Primary Pollutants are emitted from a source directly into the atmosphere. The source can either be a natural processes such as sand storms, volcanic eruption or anthropogenic (by humans) such as industial and vehicle emissions. The major primary pollutants are oxides of Sulphur, Nitrogen, Carbon, Particulate matter, Methane, Ammonia, Chlorofluorocarbons, Toxic metals etc. The Secondary Pollutants are not emitted directly. They are formed in the atmosphere when the primary pollutants react with themselves or with the other components of the atmosphere. Major secondary pollutants include photochemical oxidants and secondary particulate matter. Photochemical oxidants result from the photochemical reactions between sunlight and nitrogen oxides, sulphur dioxide, or volatile organic compounds. They mainly include acids, nitrogen dioxide, sulphur trioxide, and ozone. Ozone is considered as highly dangerous air pollutant. Exposure to ozone can cause many lung diseases such as asthma, emphysema, and bronchitis. Repeated and long exposures to ozone may even permanently scar the lung tissues. 2.3.1 Particulate Pollutant Air quality at any location is determined by the level of pollutants present in the air and it depends on the types and amount of pollutants released into the air. The level of pollutants in the air can vary greatly from one location to the other and from one hour to the next. Particulate pollution is one of the most complicated forms of air pollution. The pollutant responsible for particulate pollution is called particulate pollutant & also known as particulate matter. It is an amalgamation of different particles both sold and liquid, that behave in a similar ways and are of similar size. Particulate matter is sub-divided into different categories based on particle size i.e. PM10, PM2.5 and PM0.1. PM10 also known as coarse particles, is defined as all particles with an aerodynamic diameter of 10 µm or smaller. PM10 also contains PM2.5 and PM0.1. These particles can pose significant health threat as it can penetrate into our lungs. Once these particles get into our lungs, it can irritate the lung tissue and can prompt asthma attacks. It can also irritate our airways, nose, throat and eyes. Its sources may include construction site dust, road dust or natural dust storm, agricultural processes, plant, insects, pollen grains as well as non-combustible materials released during the burning of fossil fuels. PM2.5 also known as fine particles, is defined as all par