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    • Our Changing ur hangingEnvirOnmEnt nvirOnmEnt TexTbook exTbook
    • Our Changing Environment 2nd Edition TextbookPhilippine Copyright 2011 by DIWA LEARNING SYSTEMS INCAll rights reserved. Printed in the PhilippinesEditorial, design, and layout by University Press of First AsiaNo part of this publication may be reproduced or transmitted in any form or by any means electronicor mechanical, including photocopying, recording, or any information storage and retrieval systems,without permission in writing from the copyright owner. Exclusively distributed by DIWA LEARNING SYSTEMS INC 4/F SEDCCO 1 Bldg. 120 Thailand corner Legazpi Streets Legaspi Village, 1229 Makati City, Philippines Tel. No.: (632) 893-8501 * Fax: (632) 817-8700 ISBN 978-971-46-0189-5AuthorEdwehna Elinore P. Gayon holds a degree in Bachelor of Secondary Education major in Chemistry Education and Master of Arts in Chemistry Education from the University of the Philippines–Diliman (UP–Diliman). She is currently pursuing her degree in Doctor of Philosophy in Chemistry Education at UP–Diliman. Ms. Gayon is an assistant professor at the UP–College of Education and teaches undergraduate and graduate courses in general science and chemistry. As part of her extension work, she conducts trainings for teachers in the different regions of the Philippines. Recently, she has been involved in a collaborative research with the Faculties of Education of Universiti Kebangsaan Malaysia and Sophia University. She has also presented research papers in local and international conferences and has published articles both in education and science education in local and international journals.Consultant-ReviewerAmelia E. Punzalan has a degree in Doctor of Philosophy in Chemistry Education and Master of Arts in Chemistry from the University of the Philippines–Diliman. Currently, Ms. Punzalan is a science education specialist of the University of the Philippines–National Institute of Science and Mathematics Education Development (UP–NISMED).
    • PrEfaCE Important changes are happening constantly in our environment. Most of these changes arenatural, some are biological, and others are chemical and geological. Some of these changes mayinvolve the exchanges of energy and materials among the different parts of the environment—air, land,water, and life. One thing these changes have in common is that they all serve important purposes. Our Changing Environment 2nd Edition is a book that tackles these constant changes. It usesthe socioecological approach, emphasizing the relationship between life, environment, and society.For so long, natural changes favored life; lately, however, man-made changes have been straining thecapacity of the environment to support and sustain life on Earth. Now, the quality of the environmenthas deteriorated so badly that the very quality of life has been adversely affected. The deteriorationof the environment is a global occurrence, and its effects—acid rain; air, water, and land pollution;enhanced greenhouse effect and global warming; ozone depletion; and changing weather patterns,among others—are life-threatening. This book, which is divided into four units, aims to equip you with the scientific knowledgenecessary to understand fully the many changes in the environment. Unit I talks about the environmentyou live in. It introduces you to basic concepts about the environment, which will help you understandthe succeeding lessons. Unit II deals with the air environment, particularly the air living things breathe.Unit III focuses on concepts related to land and water. Unit IV talks about the interplay of energy, society,technology, and environment. This book also has seven useful components that will help you understand better the conceptspresented in each lesson. These components are the following:• Related Life Experiences. This serves as a springboard for the lesson to be discussed. It lets you reflect on specific situations or questions related to the lesson.• The Helpers. This is a listing of important terms and their corresponding definitions.• Bits and Pieces. This is a collection of facts and trivia relevant to the lesson.• The Connections. This connects concepts tackled in the lesson with other subject areas or fields.• Brain Exercise. This contains exercises and activities that will test your learning. It will also challenge your critical thinking and analytical skills.• Making It Real. This provides a challenging but enjoyable culminating activity.• IT Link. This provides links to online articles that you can read so you can learn more about the concepts discussed in the lesson. At the end of the year, you will learn the many changes that occur in the environment. You willbe able to establish the links between and among these many changes. You will also have a betterunderstanding on how these changes affect life and the world at large. Furthermore, you will realizehow people—you included—have changed the world for the worse. You will become aware of howpeople have contributed to the deterioration of the environment. More importantly, though, you willlearn how you can help stop this continuing deterioration. You will know how to reverse this life-threatening trend so that life can continue to exist here on Earth.
    • tablE Of COntEntsUnit I Our Living EnvironmentChapter 1 IntroductionLesson 1 Introduction to Environmental Science ..............................................................3Lesson 2 Environmental Equilibrium and the Ecosystem..................................................8Chapter 2 The Changing BiosphereLesson 1 Characteristics of the Biosphere ......................................................................16Lesson 2 The Biosphere and the Past ............................................................................20Chapter 3 Nutrient Cycles in the BiosphereLesson 1 Cycles in the Biosphere ...................................................................................32Lesson 2 Carbon, Hydrogen, and Oxygen Cycles ..........................................................38Lesson 3 Nitrogen, Sulfur, and Phosphorus Cycles ........................................................44Chapter 4 BioelementsLesson 1 Essential Elements and Their Groupings.........................................................52Lesson 2 Trace Elements and Bioselection Rules ..........................................................60Chapter 5 Energy and Life ProcessesLesson 1 Photosynthesis.................................................................................................65Lesson 2 The Food Chain ...............................................................................................74Lesson 3 Energy and the Ecosystem ..............................................................................78Unit II Our Air EnvironmentChapter 6 The Changing AtmosphereLesson 1 The Atmosphere...............................................................................................84Lesson 2 Atmospheric Phenomena.................................................................................95
    • Chapter 7 The Changing Quality of AirLesson 1 Added Substances in Air ................................................................................101Lesson 2 Air Pollution in the Philippines........................................................................ 115Chapter 8 Global Changes in the AtmosphereLesson 1 Revisiting the Greenhouse Effect .................................................................. 119Lesson 2 Global Warming: Possible Scenarios .............................................................127Lesson 3 Ozone Depletion ............................................................................................132Unit III Our Water and Land EnvironmentsChapter 9 Earth’s Water SystemsLesson 1 Water and Life ................................................................................................144Lesson 2 Water around Us ............................................................................................145Lesson 3 Properties of Bodies of Water ........................................................................156Lesson 4 Earth’s Water and Climate .............................................................................159Chapter 10 Meeting Water NeedsLesson 1 Water Distribution and Uses ..........................................................................166Lesson 2 Water Quality and Water Pollution .................................................................175Lesson 3 Measuring and Improving Water Quality ........................................................187Chapter 11 Making Soil ProductiveLesson 1 What Is Soil? ..................................................................................................194Lesson 2 Soil Productivity .............................................................................................204Chapter 12 Land Use and MisuseLesson 1 Land Use in the Philippines ...........................................................................213Lesson 2 Deforestation..................................................................................................219Lesson 3 Farming Practices ..........................................................................................225Lesson 4 Mining Lands..................................................................................................227Lesson 5 Solid Waste Problem......................................................................................230
    • Unit IV Energy, Society, Technology, and the EnvironmentChapter 13 Burning FuelsLesson 1 Energy Conversions.......................................................................................235Lesson 2 Energy Options ..............................................................................................246Chapter 14 Energy AlternativesLesson 1 Solar Energy ..................................................................................................262Lesson 2 Nuclear Energy ..............................................................................................264Lesson 3 Geothermal Energy ........................................................................................278Lesson 4 Nonconventional Energy Sources..................................................................281Chapter 15 Sustainable DevelopmentLesson 1 Aspects of Sustainable Development ............................................................288Lesson 2 Managing Resources and Population ............................................................299Glossary .......................................................................................................................305Bibliography .......................................................................................................................309Index .......................................................................................................................313
    • UNIT IOur Living Environment
    • C HAPTER 1 Introduction Have you ever experienced extreme flooding in your neighborhood? How about an abrupt rise or fall in temperature? What do you think may have caused these? Why is it important to be aware of what is happening in your environment? Fig. 1.1 Environment-friendly products and inventions Plants, animals, air, water, and soil are around us; they form part of the environment we live in. Wealso live in a world of social institutions, political organizations, and ecological diversity. In other words,we live in a socioecological world, which is an integration of the natural world and the social world. Assuch, science has played a major role in activities that provide more food, more materials, more energysupply, and more livable space for people. However, the many applications of science have also playeda role in the environmental problems we face today. Despite this, science can still provide solutions tothese environmental problems. In fact, many scientists today are actively involved in developing cleantechnologies and environment friendly materials. Through the years, the growing concern for changes in both local and global environmentshas been the focus of several environmental endeavors. One of these was the 1992 Earth Summitor the United Nations Conference on Environment and Development held in Rio de Janeiro, Brazil.The summit’s output, called Agenda 21, is a comprehensive program of actions to be adopted by the2 OUR CHANGING ENVIRONMENT 2ND EDITION
    • governments who participated in the event. Agenda 21 emphasizes the need to change economicactivities based on a new understanding of the impact of certain activities on the environment. Itadvocates the use of science in the sustainable development of Earth. The Earth Summit definedsustainable development as the wise use of resources to meet the needs and wants of the presentwithout exhausting the limits of the ecosystem’s capability to support the living community andwithout sacrificing Earth’s natural resources. In short, the Earth Summit emphasized resourcesconservation and environmental protection. A 10-year review of Agenda 21 during the World Summit on Sustainable Development was heldin Johannesburg, South Africa on September 2002. The review revealed that despite the efforts toaddress environmental concerns, many of the goals laid out in 1992 remained unrealized. As a result,a program called Education for Sustainable Development was emphasized as an essential vehicle forempowering people to preserve the environment and build a sustainable future. In December 2002,the United Nations General Assembly declared the years 2005–2014 as the Decade of Education forSustainable Development, with UNESCO as the lead agency in its implementation. In May 2009, the 5th World Environmental Education Congress was held in Montreal, Canada withthe vision “Earth as our common home.” The event promoted the importance of taking care of Earth.It called for people to change their attitudes and activities to preserve Earth’s natural resources. The link between economic development and the wise management of environmental resourcesis now generally accepted. Systematic environmental management requires balancing the use ofEarth’s resources and preserving them at the same time. These resources include land, water, minerals,timber, and wildlife. Lakes, streams, rivers, seas, oceans, and underground water are examples of waterresources. This book aims to give you a deeper understanding of the science of the environment. Knowingabout the environment using established scientific facts will let you care more about it. It is hoped,therefore, that you will also be able to help protect and sustain Earth’s life-supporting capabilities. Introduction to Environmental ScienceWhat Is Environmental Science? Organisms relate to one another through an array of interactions. These interactions are dynamic,universal, and continuous, where cycles involving both living and nonliving things intersect. Thescience that investigates the total relationships among living things and their nonliving environmentis known as ecology. Ecology was first defined in 1866 by German scientist Ernst Haeckel (1834–1919). The OUR LIVING ENVIRONMENT 3
    • word ecology is derived from the Greek word oikos, meaning “a place to live.” Corollary, the applicationof the knowledge of ecology to the management of the environment is called environmentalscience. The following is a more inclusive and holistic definition of environmental science: It is the systematic study of our environment and our place in it. Environmental science is a multidisciplinary The word environment comes subject that applies knowledge from many scientific from the French word environner, disciplines. As you study ecological relationships, which means to “encircle or you may have to recall relevant concepts you have surround.” It can be defined as learned in other science courses, notably, biology, • the circumstances and conditions chemistry, physics, geology, and meteorology. Also that surround an organism or a integrated are information from other fields such as group of organisms; or agriculture, forestry, mathematics, engineering, and • the social and cultural conditions resource conservation and management. Furthermore, that affect an individual or a environmental science involves the social sciences such community. as sociology, economics, political science, demography, geography, psychology, and ethics. Scientific principles that are relevant to the study of the environment are not as straightforwardas those resulting from scientific investigations conducted in laboratories. Unlike scientific laboratories,where conditions can be controlled and closely monitored, the environment is a complex system. Thus,coming up with simple solutions to environmental problems can be extremely challenging. A study of the environment becomes more meaningful when we place organisms in the core ofall relationships. We study the conditions, events, and influences that affect life and how life in turnresponds to these aspects. We are concerned with conditions that limit life, the use of resources byliving things, and the interaction of living things with their environment. But what exactly comprises the environment of an organism? The total environment of anorganism includes all other forms of life on Earth and its nonliving environment. The nonlivingenvironment is made up of substances such as nitrogen, oxygen, water, carbon dioxide, calciumcarbonate, phosphates, and the organic by-products of the organism’s activities. It also includesphysical factors such as moisture, wind, tides, ocean currents, temperature, light, and topographicalfactors such as altitude and slope.4 OUR CHANGING ENVIRONMENT 2ND EDITION
    • This book will provide you a deeper understanding of the nature of the relationships that existbetween organisms and their environment. You will discover the great order in our environment andthe unforeseen negative impact of our activities on this very same environment. In all likelihood, thegeneral lack of concern for our environment stems from the lack of understanding of the delicaterelationships that exist in it. Are you aware that manipulating one part of the environment triggers aseries of events that can have serious effects on its other parts?Studying an Ecosystem In studying ecologicalrelationships, you should start byfocusing on a smaller system. A systemis any part of the environment thatis selected for the purpose of study.You may be interested in studying apond, a decaying log, an aquarium,a terrarium, or a field. Ecologistsmay choose to study a grassland, aforest, a river, or an ocean. These aresome examples of ecosystems. Anecosystem or ecological system isthe basic functioning unit of nature. Fig. 1.2 In an ecosystem, a community of organisms interact with their environment.It consists of the nonliving (abiotic)environment and the living (biotic) community it supports. These two components are intimatelylinked by a variety of biological, chemical, and physical processes. The biotic and abiotic componentsfunction together through an exchange of materials (matter) and energy. There is an assortment of ecosystems to study. Ecosystems may be small or large, terrestrial ormarine, artificial or natural. No two ecosystems are exactly alike in composition, but there would beecological equivalents with comparable functions. Ecological equivalents are unrelated organismsthat occupy similar habitats and resemble each other. For instance, sharks (fish) and dolphins(mammals) live in a marine habitat and they specifically resemble one another. Moreover, there are nosharp boundaries between ecosystems. A river, for example, exchanges materials and energy with anadjacent forest. OUR LIVING ENVIRONMENT 5
    • Consider the field of environmental • An organism is any form of life. chemical analysis. This field poses a major Organisms are classified into species. challenge to chemists for two reasons. First, • A species is a group of organisms that the properties of the environment change resemble one another in appearance, with time and in space. Many conditions behavior, chemistry, and genetic operate simultaneously within this complex makeup. They can produce offspring of natural system. Second, environmentally their own kind. significant concentrations of substances are • The organisms in a given ecosystem form usually at trace levels—in parts per a community. Within the community, million (ppm), sometimes even in parts per organisms are grouped into populations. billion (ppb) levels. • A population is a group of interacting Before the development of sensitive organisms of the same species that analytical instruments, chemical analyses of occupy a particular space at a particular environmental samples were very difficult, if time. not impossible, in certain cases. Such analyses require meticulous preparation of the sample,utmost cleanliness of glassware, skillful execution of the analytical procedure, and high sensitivity andprecision of the instruments used. Other scientists conduct environmental studies in natural settings that require the use ofsophisticated instruments. For example, information about the thinning of the ozone layer has beengathered using meteorological instruments mounted on airborne balloons. Another example is theuse of satellites to gather data about the surface of Earth and its oceans. Fig. 1.3 Scientists at work on environmental studies6 OUR CHANGING ENVIRONMENT 2ND EDITION
    • Environmental scientists can hypothesize about the behavior of environmental systems based onprevious observations and accumulated facts about the environment. They often resort to modelingto come up with valid information about selected parts of the environment. Modeling of naturalphenomena is done using powerful computers. Modeling is an important tool in scientific studies as itallows scientists to simulate complex systems. You can also gather information about the environment from day-to-day observations or frommore formal environmental studies.Units of Measure Certain substances in the environment can exert significant effects even at concentrations youmay consider insignificant. To illustrate, just look at the amount of carbon dioxide (CO2) the air contains. During the Intergovernmental Panel on Climate Change held in Fiji, Japan on June 2007, scientistsreported that the air contained 379 ppm CO2, which was based on data gathered in 2005. This meansthat there are 379 cubic centimeters (cm3) of CO2 in 1 000 000 cm3 of air. This can be expressed inpercent or parts per hundred: 100 379 cm3 CO2 x = 0.0379% 1 x 106 cm3 air In terms of mass per unit volume, 1 ppm is equivalent to 1 milligram per liter (mg/L). Some substances have significant effects even at ppb level. Sulfur dioxide (SO2) in air, for example,may be present at 50 ppb. This means that for every 109 cm3 of air, there are 50 cm3 of SO2. Sulfurdioxide at 0.1 to 0.5 ppm can harm plants or cause respiratory illness in humans. Did you know that since the Pre-Industrial Age (1790s–1860s), the amount of CO2 in the air has increased from 280 to 379 ppm (an increase of 35%)? OUR LIVING ENVIRONMENT 7
    • 1. Why is it important to monitor the amount of gases such as CO2 and SO2 in the air? 2. If the concentration of carbon monoxide in the air is 5 ppm, how much is this in a. percent? b. ppb? Environmental Equilibrium and the Ecosystem Observe an object or a portion of the environment such as a piece of rock, a river, or a rice field.Does it look exactly the same today as it was, for instance, a year ago? Do you think its propertieschanged?Environmental Equilibrium The environment is constantly changing. These changes occur with time and in space. Theoccurrence of change in the properties of an object or system is referred to as an event. Some eventsoccur very slowly such that the change may not be evident at once. Consider the wearing of rocks intosoil; this may take centuries to complete. Other changes such as the flash of lightning occur very fast.More measurable changes are those that occur at intermediate rates. All natural changes occur because of the tendency of systems to reach a state of balance orequilibrium. A rice field may look the same each year during the same season when all the changestaking place in it have reached a state of natural balance. When that happens, such a system hasreached environmental equilibrium. Is the equilibrium established in a chemical system the same as the equilibrium attained in anecosystem? Chemical equilibrium is described as dynamic, where opposing reactions occur at equal rates.Environmental equilibrium, on the other hand, is steady state in nature and is established in an opensystem. Steady-state equilibrium means the inputs and outputs to and from the system in terms ofenergy or a given material are equal.8 OUR CHANGING ENVIRONMENT 2ND EDITION