Our Changing EnvirOnmEnt

Our Changing EnvirOnmEnt

Te x T b o o kTe x T b o o k

Our Changing Environment 2nd Edition Textbook

Philippine Copyright 2011 by DIWA LEARNING SYSTEMS INCAll rights reserved. Printed in the Philippines

Editorial, design, and layout by University Press of First Asia

No part of this publication may be reproduced or transmitted in any form or by any means electronic or mechanical, including photocopying, recording, or any information storage and retrieval systems, without permission in writing from the copyright owner.

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ISBN 978-971-46-0189-5

AuthorEdwehna Elinore P. Gayon holds a degree in Bachelor of Secondary Education major inChemistryEducation andMaster ofArts inChemistryEducation from theUniversity of thePhilippines–Diliman(UP–Diliman).SheiscurrentlypursuingherdegreeinDoctorofPhilosophyinChemistryEducationatUP–Diliman.Ms.GayonisanassistantprofessorattheUP–CollegeofEducationandteachesundergraduateandgraduatecoursesingeneralscienceandchemistry.Aspartofherextensionwork,sheconductstrainingsforteachersinthedifferentregionsofthePhilippines.Recently,shehasbeeninvolvedinacollaborativeresearchwith theFacultiesofEducationofUniversitiKebangsaanMalaysiaandSophiaUniversity.Shehasalsopresentedresearchpapersinlocalandinternationalconferencesandhaspublishedarticlesbothineducationandscienceeducationinlocalandinternationaljournals.

Consultant-ReviewerAmelia E. PunzalanhasadegreeinDoctorofPhilosophyinChemistryEducationandMasterofArtsinChemistryfromtheUniversityofthePhilippines–Diliman.Currently,Ms.PunzalanisascienceeducationspecialistoftheUniversityofthePhilippines–NationalInstituteofScienceandMathematicsEducationDevelopment(UP–NISMED).

PrEfaCE

Important changes are happening constantly in our environment. Most of these changes are natural, some are biological, and others are chemical and geological. Some of these changes may involve 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 uses the 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 the capacity of the environment to support and sustain life on Earth. Now, the quality of the environment has deteriorated so badly that the very quality of life has been adversely affected. The deterioration of 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 knowledge necessary to understand fully the many changes in the environment. Unit I talks about the environment you live in. It introduces you to basic concepts about the environment, which will help you understand the 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 concepts presented 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 will be able to establish the links between and among these many changes. You will also have a better understanding on how these changes affect life and the world at large. Furthermore, you will realize how people—you included—have changed the world for the worse. You will become aware of how people have contributed to the deterioration of the environment. More importantly, though, you will learn 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.

Unit I Our Living EnvironmentChapter 1 Introduction

Lesson 1 Introduction to Environmental Science ..............................................................3

Lesson 2 Environmental Equilibrium and the Ecosystem ..................................................8

Chapter 2 The Changing Biosphere

Lesson 1 Characteristics of the Biosphere ......................................................................16

Lesson 2 The Biosphere and the Past ............................................................................20

Chapter 3 Nutrient Cycles in the Biosphere

Lesson 1 Cycles in the Biosphere ...................................................................................32

Lesson 2 Carbon, Hydrogen, and Oxygen Cycles ..........................................................38

Lesson 3 Nitrogen, Sulfur, and Phosphorus Cycles ........................................................44

Chapter 4 Bioelements

Lesson 1 Essential Elements and Their Groupings .........................................................52

Lesson 2 Trace Elements and Bioselection Rules ..........................................................60

Chapter 5 Energy and Life Processes

Lesson 1 Photosynthesis .................................................................................................65

Lesson 2 The Food Chain ...............................................................................................74

Lesson 3 Energy and the Ecosystem ..............................................................................78

Unit II Our Air EnvironmentChapter 6 The Changing Atmosphere

Lesson 1 The Atmosphere ...............................................................................................84

Lesson 2 Atmospheric Phenomena .................................................................................95

tablE Of COntEnts

Chapter 7 The Changing Quality of Air

Lesson 1 Added Substances in Air ................................................................................101

Lesson 2 Air Pollution in the Philippines ........................................................................115

Chapter 8 Global Changes in the Atmosphere

Lesson 1 Revisiting the Greenhouse Effect ..................................................................119

Lesson 2 Global Warming: Possible Scenarios .............................................................127

Lesson 3 Ozone Depletion ............................................................................................132

Unit III Our Water and Land EnvironmentsChapter 9 Earth’s Water Systems

Lesson 1 Water and Life ................................................................................................144

Lesson 2 Water around Us ............................................................................................145

Lesson 3 Properties of Bodies of Water ........................................................................156

Lesson 4 Earth’s Water and Climate .............................................................................159

Chapter 10 Meeting Water Needs

Lesson 1 Water Distribution and Uses ..........................................................................166

Lesson 2 Water Quality and Water Pollution .................................................................175

Lesson 3 Measuring and Improving Water Quality ........................................................187

Chapter 11 Making Soil Productive

Lesson 1 What Is Soil? ..................................................................................................194

Lesson 2 Soil Productivity .............................................................................................204

Chapter 12 Land Use and Misuse

Lesson 1 Land Use in the Philippines ...........................................................................213

Lesson 2 Deforestation ..................................................................................................219

Lesson 3 Farming Practices ..........................................................................................225

Lesson 4 Mining Lands ..................................................................................................227

Lesson 5 Solid Waste Problem......................................................................................230

Unit IV Energy, Society, Technology, and the EnvironmentChapter 13 Burning Fuels

Lesson 1 Energy Conversions .......................................................................................235

Lesson 2 Energy Options ..............................................................................................246

Chapter 14 Energy Alternatives

Lesson 1 Solar Energy ..................................................................................................262

Lesson 2 Nuclear Energy ..............................................................................................264

Lesson 3 Geothermal Energy ........................................................................................278

Lesson 4 Nonconventional Energy Sources ..................................................................281

Chapter 15 Sustainable Development

Lesson 1 Aspects of Sustainable Development ............................................................288

Lesson 2 Managing Resources and Population ............................................................299

Glossary .......................................................................................................................305Bibliography .......................................................................................................................309Index .......................................................................................................................313

Our Living EnvironmentOur Living EnvironmentIIUNIT

OUR CHANGING ENVIRONMENT 2ND EDITION2

Introduction CHAPTER 1

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?

Plants, animals, air, water, and soil are around us; they form part of the environment we live in. We

also 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. As

such, science has played a major role in activities that provide more food, more materials, more energy

supply, and more livable space for people. However, the many applications of science have also played

a role in the environmental problems we face today. Despite this, science can still provide solutions to

these environmental problems. In fact, many scientists today are actively involved in developing clean

technologies and environment friendly materials.

Through the years, the growing concern for changes in both local and global environments

has been the focus of several environmental endeavors. One of these was the 1992 Earth Summit

or 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 the

Fig. 1.1 Environment-friendly products and inventions

OUR LIVING ENVIRONMENT 3

governments who participated in the event. Agenda 21 emphasizes the need to change economic

activities based on a new understanding of the impact of certain activities on the environment. It

advocates the use of science in the sustainable development of Earth. The Earth Summit defined

sustainable development as the wise use of resources to meet the needs and wants of the present

without exhausting the limits of the ecosystem’s capability to support the living community and

without sacrificing Earth’s natural resources. In short, the Earth Summit emphasized resources

conservation and environmental protection.

A 10-year review of Agenda 21 during the World Summit on Sustainable Development was held

in Johannesburg, South Africa on September 2002. The review revealed that despite the efforts to

address 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 for

empowering 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 for

Sustainable Development, with UNESCO as the lead agency in its implementation.

In May 2009, the 5th World Environmental Education Congress was held in Montreal, Canada with

the 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 resources

is now generally accepted. Systematic environmental management requires balancing the use of

Earth’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 water

resources.

This book aims to give you a deeper understanding of the science of the environment. Knowing

about 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 Science

What 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. The

science that investigates the total relationships among living things and their nonliving environment

is known as ecology. Ecology was first defined in 1866 by German scientist Ernst Haeckel (1834–1919). The

OUR CHANGING ENVIRONMENT 2ND EDITION4

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

subject that applies knowledge from many scientific

disciplines. As you study ecological relationships,

you may have to recall relevant concepts you have

learned in other science courses, notably, biology,

chemistry, physics, geology, and meteorology. Also

integrated are information from other fields such as

agriculture, forestry, mathematics, engineering, and

resource conservation and management. Furthermore,

environmental science involves the social sciences such

as sociology, economics, political science, demography,

geography, psychology, and ethics.

word ecology is derived from the Greek word oikos, meaning “a place to live.” Corollary, the application

of the knowledge of ecology to the management of the environment is called environmental

science.

Scientific principles that are relevant to the study of the environment are not as straightforward

as 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 of

all relationships. We study the conditions, events, and influences that affect life and how life in turn

responds to these aspects. We are concerned with conditions that limit life, the use of resources by

living things, and the interaction of living things with their environment.

But what exactly comprises the environment of an organism? The total environment of an

organism includes all other forms of life on Earth and its nonliving environment. The nonliving

environment is made up of substances such as nitrogen, oxygen, water, carbon dioxide, calcium

carbonate, phosphates, and the organic by-products of the organism’s activities. It also includes

physical factors such as moisture, wind, tides, ocean currents, temperature, light, and topographical

factors such as altitude and slope.

The word environment comes from the French word environner, which means to “encircle or surround.” It can be defined as• the circumstances and conditions

that surround an organism or a group of organisms; or

• the social and cultural conditions that affect an individual or a community.

OUR LIVING ENVIRONMENT 5

This book will provide you a deeper understanding of the nature of the relationships that exist

between organisms and their environment. You will discover the great order in our environment and

the unforeseen negative impact of our activities on this very same environment. In all likelihood, the

general lack of concern for our environment stems from the lack of understanding of the delicate

relationships that exist in it. Are you aware that manipulating one part of the environment triggers a

series of events that can have serious effects on its other parts?

Studying an Ecosystem

In studying ecological

relationships, you should start by

focusing on a smaller system. A system

is any part of the environment that

is selected for the purpose of study.

You may be interested in studying a

pond, a decaying log, an aquarium,

a terrarium, or a field. Ecologists

may choose to study a grassland, a

forest, a river, or an ocean. These are

some examples of ecosystems. An

ecosystem or ecological system is

the basic functioning unit of nature.

It consists of the nonliving (abiotic)

environment and the living (biotic) community it supports. These two components are intimately

linked by a variety of biological, chemical, and physical processes. The biotic and abiotic components

function together through an exchange of materials (matter) and energy.

There is an assortment of ecosystems to study. Ecosystems may be small or large, terrestrial or

marine, artificial or natural. No two ecosystems are exactly alike in composition, but there would be

ecological equivalents with comparable functions. Ecological equivalents are unrelated organisms

that 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 no

sharp boundaries between ecosystems. A river, for example, exchanges materials and energy with an

adjacent forest.

Fig. 1.2 In an ecosystem, a community of organisms interact with their

environment.

OUR CHANGING ENVIRONMENT 2ND EDITION6

• An organism is any form of life. Organisms are classified into species.

• A species is a group of organisms that resemble one another in appearance, behavior, chemistry, and genetic makeup. They can produce offspring of their own kind.

• The organisms in a given ecosystem form a community. Within the community, organisms are grouped into populations.

• A population is a group of interacting organisms of the same species that occupy a particular space at a particular time.

Consider the field of environmental

chemical analysis. This field poses a major

challenge to chemists for two reasons. First,

the properties of the environment change

with time and in space. Many conditions

operate simultaneously within this complex

natural system. Second, environmentally

significant concentrations of substances are

usually at trace levels—in parts per

million (ppm), sometimes even in parts per

billion (ppb) levels.

Before the development of sensitive

analytical instruments, chemical analyses of

environmental samples were very difficult, if

not impossible, in certain cases. Such analyses

require meticulous preparation of the sample,

Fig. 1.3 Scientists at work on environmental studies

utmost cleanliness of glassware, skillful execution of the analytical procedure, and high sensitivity and

precision of the instruments used.

Other scientists conduct environmental studies in natural settings that require the use of

sophisticated instruments. For example, information about the thinning of the ozone layer has been

gathered using meteorological instruments mounted on airborne balloons. Another example is the

use of satellites to gather data about the surface of Earth and its oceans.

OUR LIVING ENVIRONMENT 7

Environmental scientists can hypothesize about the behavior of environmental systems based on

previous observations and accumulated facts about the environment. They often resort to modeling

to come up with valid information about selected parts of the environment. Modeling of natural

phenomena is done using powerful computers. Modeling is an important tool in scientific studies as it

allows scientists to simulate complex systems.

You can also gather information about the environment from day-to-day observations or from

more formal environmental studies.

Units of Measure

Certain substances in the environment can exert significant effects even at concentrations you

may consider insignificant. To illustrate, just look at the amount of carbon dioxide (CO2) the air contains.

During the Intergovernmental Pa nel on Climate Change held in Fiji, Japan on June 2007, scientists

reported that the air contained 379 ppm CO2, which was based on data gathered in 2005. This means

that there are 379 cubic centimeters (cm3) of CO2 in 1 000 000 cm3 of air. This can be expressed in

percent or parts per hundred:

379 cm3 CO2 x

100 = 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. Sulfur

dioxide 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 CHANGING ENVIRONMENT 2ND EDITION8

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 properties

changed?

Environmental Equilibrium

The environment is constantly changing. These changes occur with time and in space. The

occurrence of change in the properties of an object or system is referred to as an event. Some events

occur very slowly such that the change may not be evident at once. Consider the wearing of rocks into

soil; 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 or

equilibrium. A rice field may look the same each year during the same season when all the changes

taking place in it have reached a state of natural balance. When that happens, such a system has

reached environmental equilibrium.

Is the equilibrium established in a chemical system the same as the equilibrium attained in an

ecosystem?

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 open

system. Steady-state equilibrium means the inputs and outputs to and from the system in terms of

energy or a given material are equal.