science and the environment chapter · 2020-03-31 · many fields of study environmental science is...

Science and the EnvironmentC H A P T E R 1

1 Understanding OurEnvironment

2 The Environment andSociety

More than 2,700 m (9,000 ft)above sea level, a forest ecologistis studying biodiversity in a CostaRican rain forest. To ascend to thetreetops, he shoots an arrow over abranch and hauls himself up withthe attached rope.

Before you read this chapter,take a few minutes toanswer the following questions in your EcoLog.

1. How do you define theterm environment? Arehumans part of the environment?

2. How can science help usunderstand and solve environmental problems?

READING WARM-UP

4 Chapter 1 Science and the EnvironmentCopyright© by Holt, Rinehart and Winston. All rights reserved.

Section 1 Understanding Our Environment 5

When someone mentions the term environment, some peoplethink of a beautiful scene, such as a stream flowing through awilderness area or a rain-forest canopy alive with bloomingflowers and howling monkeys. You might not think of yourbackyard or neighborhood as part of your environment. In fact,the environment is everything around us. It includes the naturalworld as well as things produced by humans. But the environ-ment is also more than what you can see—it is a complex webof relationships that connects us with the world we live in.

What Is Environmental Science?The students from Keene High School in Figure 1 are searchingthe Ashuelot River in New Hampshire for dwarf wedge mussels.The mussels, which were once abundant in the river, are now indanger of disappearing completely—and the students want toknow why. To find out more, the students test water samplesfrom different parts of the river and conduct experiments. Couldthe problem be that sewage is contaminating the water? Or couldfertilizer from a nearby golf course be causing algae in the riverto grow rapidly and use up the oxygen that the mussels need tosurvive? Another possible explanation might be that a small damon the river is disrupting the mussels’ reproduction.

The students’ efforts have been highly praised and widelyrecognized. Yet they hope for a more meaningful reward—thepreservation of an endangered species. The students’ work is justone example of a relatively new field— thestudy of how humans interact with the environment.

environmental science,

Objectives� Define environmental science, and

compare environmental sciencewith ecology.

� List the five major fields of studythat contribute to environmentalscience.

� Describe the major environmentaleffects of hunter-gatherers, theagricultural revolution, and theIndustrial Revolution.

� Distinguish between renewableand nonrenewable resources.

� Classify environmental problemsinto three major categories.

Key Termsenvironmental scienceecologyagriculturenatural resourcepollutionbiodiversity

S E C T I O N 1

Understanding Our Environment

Figure 1 � These students arecounting the number of dwarfwedge mussels in part of theAshuelot River. They hope that thedata they collect will help preservethis endangered species.

Copyright© by Holt, Rinehart and Winston. All rights reserved.

The Goals of Environmental Science One of the major goals ofenvironmental science is to understand and solve environmentalproblems. To accomplish this goal, environmental scientists studytwo main types of interactions between humans and their envi-ronment. One area of study focuses on how we use naturalresources, such as water and plants. The other area of studyfocuses on how our actions alter our environment. To study theseinteractions, environmental scientists must gather and analyzeinformation from many different disciplines.

Many Fields of Study Environmental science is an interdiscipli-nary science, which means that it involves many fields of study.One important foundation of environmental science is ecology.

is the study of how living things interact with each otherand with their nonliving environment. For example, an ecologistmight study the relationship between bees and the plants beespollinate. However, an environmental scientist might investigatehow the nesting behavior of bees is influenced by human activi-ties such as the planting of suburban landscaping.

Many sciences other than ecology also contribute to environ-mental science. For example, chemistry helps us understand thenature of pollutants. Geology helps us model how pollutantstravel underground. Botany and zoology can provide informationneeded to preserve species. Paleontology, the study of fossils, canhelp us understand how Earth’s climate has changed in the past.Using such information about the past can help us predict howfuture climate changes could affect life on Earth. At any giventime, an environmental scientist may use information provided byother sciences. Figure 2 shows a few examples of disciplines thatcontribute to environmental science.

Ecology

6 Chapter 1

HistoryConnection to

Rachel Carson Alarmed by theincreasing levels of pesticides andother chemicals in the environ-ment, biologist Rachel Carsonpublished Silent Spring in 1962.Carson imagined a spring morn-ing that was silent because thebirds and frogs were dead afterbeing poisoned by pesticides.Carson’s carefully researchedbook was enthusiastically receivedby the public and was read bymany other scientists as well aspolicy makers and politicians.However, many people in thechemical industry saw SilentSpring as a threat to their pesti-cide sales and launched a$250,000 campaign to discreditCarson. Carson’s research pre-vailed, although she died in1964—unaware that the bookshe had written was instrumentalin the birth of the modern envi-ronmental movement.

Figure 2 � Many Fields of Study

� This marine biologist (right) isstudying a marine mammal calleda manatee.

� This ornithologist (above) isstudying the nesting behavior ofseabirds called albatrosses.


But studying the environment also involves studying humanpopulations, so environmental scientists may use information fromthe social sciences, which include economics, law, politics, andgeography. Social sciences can help us answer questions such as,How do cultural attitudes affect the ways that people use the U.S.park system? or How does human migration from rural to urbanareas affect the local environment? Table 1 lists some of the majorfields of study that contribute to the study of environmental science.


Major Fields of Study That Contribute to Environmental Science

Geography is the study of the relationship between human populations and Earth’s features.Anthropology is the study of the interactions of the biological, cultural, geographical,and historical aspects of humankind.Sociology is the study of human population dynamics and statistics.

Social sciences arethe study of humanpopulations.

Biochemistry is the study of the chemistry of living things.Geochemistry, a branch of geology, is the study of the chemistry of materialssuch as rocks, soil, and water.

Chemistry is thestudy of chemicalsand their interactions.

Engineering is the science by which matter and energy are made useful tohumans in structures, machines, and products.

Physics is the study of matter and energy.

Geology is the study of the Earth’s surface, interior processes, and history.Paleontology is the study of fossils and ancient life.Climatology is the study of the Earth’s atmosphere and climate.Hydrology is the study of Earth’s water resources.

Earth science is thestudy of the Earth’snonliving systems andthe planet as a whole.

Zoology is the study of animals.Botany is the study of plants.Microbiology is the study of microorganisms.Ecology is the study of how organisms interact with their environment and each other.

Biology is the studyof living organisms.

Table 1 �

� This geologist is studying a volcano in Hawaii.

� This biologist is examining a plantthat was grown in a lab from just afew cells.

www.scilinks.orgTopic: Careers inEnvironmental ScienceSciLinks code: HE4010


Scientists as Citizens, Citizens as ScientistsGovernments, businesses, and cities recognize that studying ourenvironment is vital to maintaining a healthy and productive soci-ety. Thus, environmental scientists are often asked to share theirresearch with the world. Figure 3 shows scientists at a press con-ference that was held after a meeting on climate change.

Often, the observations of nonscientists are the first steptoward addressing an environmental problem. For example, whendeformed frogs started appearing in lakes in Minnesota, middleschool students noticed the problem first. Likewise, the students atDublin Scioto High School in Ohio, shown in Figure 3, study boxturtle habitats every year. The students want to find out how theseendangered turtles live and what factors affect the turtles’ nestingand hibernation sites. The students track the turtles, measure theatmospheric conditions, analyze soil samples, and map the move-ments of the small reptiles. Why do these efforts matter? Theymatter because the box turtle habitat is threatened. At the end ofthe year, students present their findings to city planners in hopesthat the most sensitive turtle habitats will be protected.

8 Chapter 1 Science and the Environment

1. Describe the two main types of interactions that envi-ronmental scientists study. Give an example of each.

2. Describe the major fields of study that contribute toenvironmental science.

3. Explain why environmental science is an interdisci-plinary science.

CRITICAL THINKING4. Making Comparisons What is the difference

between environmental science and ecology?

5. Making Inferences Read the Ecofact. Propose asolution to prevent the environmental problems ofthe seaport of Troy described in the Ecofact.

READING SKILLS

S E C T I O N 1 Mid-Section Review

Figure 3 � Environmental Scienceand Public Life Scientists hold apress conference on climate change(above). Students (right) are studyingthe movements of box turtles.

EcofactThe Fall of Troy Environmentalproblems are nothing new. Nearly3,000 years ago, the Greek poetHomer wrote about the ancientseaport of Troy, which was locatedbeneath a wooded hillside. TheTrojans cut down all the trees onthe surrounding hills. Without treesto hold the soil in place, rainwashed the soil into the harbor.So much silt accumulated in theharbor that large ships could notenter and Troy’s economy collapsed.Today, the ruins of Troy are severalmiles from the sea.


Our Environment Through TimeYou may think that environmental change is a modernissue, but wherever humans have hunted, grownfood, or settled, they have changed the environ-ment. For example, the land where New York Citynow stands was once an area where NativeAmericans hunted game and gathered food, asshown in Figure 4. The environmental changethat occurred on Manhattan Island over the last300 years was immense, yet that period of timewas just a “blink” in human history.

Hunter-Gatherers For most of human history, peoplewere hunter-gatherers, or people who obtain food bycollecting plants and by hunting wild animals or scavengingtheir remains. Early hunter-gatherer groups were small, and theymigrated from place to place as different types of food becameavailable at different times of the year. Even today there arehunter-gatherer societies in the Amazon rain forests of SouthAmerica and in New Guinea, as shown in Figure 5.

Hunter-gatherers affect their environment in many ways. Forexample, some Native American tribes hunted bison, which livein grasslands. The tribes set fires to burn the prairies and preventthe growth of trees. In this way, the tribes kept the prairies asopen grassland where they could hunt bison. In addition, hunter-gatherer groups probably helped spread plants to areas where theplants did not originally grow.

In North America, a combination of rapid climate changes andoverhunting by hunter-gatherers may have led to the disappearanceof some large mammal species. These species include giant sloths,giant bison, mastodons, cave bears, and saber-toothed cats. Hugepiles of bones have been found in places where ancient hunter-gatherers drove thousands of animals into pits and killed them.


Figure 5 � This modern hunter-gatherer group lives in New Guinea,a tropical island off the north coast ofAustralia.

Figure 4 � Three hundred years agoManhattan was a much differentplace. This painting shows an areawhere Native Americans hunted and fished.


The Agricultural Revolution Eventually many hunter-gatherergroups began to collect the seeds of the plants they gathered and todomesticate some of the animals in their environment.is the practice of growing, breeding, and caring for plants and ani-mals that are used for food, clothing, housing, transportation, andother purposes. The practice of agriculture started in many differ-ent parts of the world over 10,000 years ago. This change hadsuch a dramatic impact on human societies and their environmentthat it is often called the agricultural revolution.

The agricultural revolution allowed human populations to growat an unprecedented rate. An area of land can support up to 500times as many people by farming as it can by hunting and gathering.As populations grew, they began to concentrate in smaller areas.These changes placed increased pressure on local environments.

The agricultural revolution also changed the food we eat. Theplants we grow and eat today are descended from wild plants.During harvest season, farmers collected seeds from plants thatexhibited the qualities they desired. The seeds of plants with largekernels or sweet and nutritious flesh were planted and harvestedagain. Over the course of many generations, the domesticatedplants became very different from their wild ancestors. For exam-ple, the grass shown in Figure 6 may be related to the grass thatcorn was bred from.

As grasslands, forests, and wetlands were replaced with farm-land, habitat was destroyed. Slash-and-burn agriculture, shown inFigure 7, is one of the earliest ways that land was converted tofarmland. Replacing forest with farmland on a large scale cancause soil loss, floods, and water shortages. In addition, much ofthis converted land was farmed poorly and is no longer fertile. Thedestruction of farmland had far-reaching environmental effects. Forexample, the early civilizations of the Tigris-Euphrates River basincollapsed, in part, because the overworked soil became water-logged and contaminated by salts.

Agriculture

10 Chapter 1

Figure 6 � This grass is thought tobe a relative of the modern corn plant.Native Americans may have selectivelybred a grass like this to produce corn.

Figure 7 � For thousands of yearshumans have burned forests to create fields for agriculture. In thisphoto, a rain forest in Thailand isbeing cleared for farming.

FIELD ACTIVITY FIELD ACTIVITY Germinating Corn Many peo-ple do not realize how easy it is togrow corn plants from unpoppedpopcorn kernels. This ancient grasswill sprout in a matter of days if itis watered frequently. Place a fewpopcorn kernels on a wet papertowel, and place the paper towelin a clear plastic cup so that thekernels are visible from the outside.Leave the cup on a windowsillfor several days and water it fre-quently. As your plant grows, see if you can observe any grasslikefeatures. Record your observationsin your EcoLog.


The Industrial Revolution For almost 10,000 years the tools ofhuman societies were powered mainly by humans or animals.However, this pattern changed dramatically in the middle of the1700s with the Industrial Revolution. The Industrial Revolutioninvolved a shift from energy sources such as animal muscle andrunning water, to fossil fuels, such as coal and oil. The increaseduse of fossil fuels and machines, such as the steam engines shownin Figure 8, changed society and greatly increased the efficiencyof agriculture, industry, and transportation.

During the Industrial Revolution, the large-scale productionof goods in factories became less expensive than the local pro-duction of handmade goods. On the farm, machinery furtherreduced the amount of land and human labor needed to producefood. As fewer people grew their own food, populations inurban areas steadily grew. Fossil fuels and motorized vehiclesalso allowed food and other goods to be transported cheaplyacross great distances.

Improving Quality of Life The Industrial Revolution introducedmany positive changes. Inventions such as the light bulb greatlyimproved our quality of life. Agricultural productivity increased,and sanitation, nutrition, and medical care vastly improved. Yetwith all of these advances, the Industrial Revolution introducedmany new environmental problems. As the human populationgrew, many environmental problems such as pollution and habi-tat loss became more common.

In the 1900s, modern societies increasingly began to use arti-ficial substances in place of raw animal and plant products.Plastics, artificial pesticides and fertilizers, and many other ma-terials are the result of this change. While many of these productshave made life easier, we are now beginning to understand someof the environmental problems they present. Much of environ-mental science is concerned with the problems associated with theIndustrial Revolution.


Figure 8 � During much of theIndustrial Revolution, few limits wereplaced on the air pollution caused byburning fossil fuels. Locomotives suchas these are powered by burning coal.

Figure 9 � Modern communicationtechnology, such as radios, TVs, andcomputers characterize the laterstages of the Industrial Revolution.



Lake Washington: An EnvironmentalSuccess Story

Figure 10 � This photograph wastaken from the moon’s surface in1968 by the crew of Apollo 8.Photographs such as this helped people realize the uniqueness of theplanet we share.

Seattle is located on a narrow stripof land between two large bodies ofwater. To the west is the PugetSound, which is part of the PacificOcean, and to the east is Lake Wash-ington, which is a deep freshwaterlake. During the 1940s and early1950s, cities on the east side of LakeWashington built 11 sewer systemsthat emptied into the lake. Unlikeraw sewage, this sewage was treatedand was not a threat to humanhealth. So, people were surprised byresearch in 1955 showing that thetreated sewage was threatening theirlake. Scientists working in Dr. W. T.Edmondson’s lab at the University ofWashington found a bacterium,Oscillatoria rubescens, that had neverbeen seen in the lake before.

Dr. Edmondson knew that inseveral lakes in Europe, pollutionfrom sewage had been followed by

allowing it to build up in anenclosed lake.

Cities around the lake had towork together to connect theirsewage plants to large lines thatwould carry the treated sewage toPuget Sound. Because there was nolegal way for cities to connect plants

the appearance of O. rubescens. Ashort time after, the lakes deterio-rated severely and became cloudy,smelly, and unable to support fish.The scientists studying Lake Wash-ington realized that they were see-ing the beginning of this process.

About this same time, Seattleset up the Metropolitan ProblemsAdvisory Committee, chaired byJames Ellis. Dr. Edmondson wroteEllis a letter that explained whatcould be expected in the future ifaction was not taken. The best solu-tion to the problem seemed to beto pump the sewage around thelake and empty it deep into PugetSound. Although this solution mayseem like it would save one body ofwater by polluting another one, itwas actually a good choice. Dilutingthe sewage in Puget Sound is less ofan environmental problem than

Spaceship EarthEarth has been compared to a ship traveling through space thatcannot dispose of waste or take on new supplies as it travels.Earth is essentially a closed system—the only thing that entersEarth’s atmosphere in large amounts is energy from the sun, andthe only thing that leaves in large amounts is heat. A closed sys-tem of this sort has some potential problems. Some resources arelimited, and as the population grows, the resources will be usedmore rapidly. In a closed system, there is also the chance that wewill produce wastes more quickly than we can dispose of them.

Although the Earth can be thought of as a complete system, envi-ronmental problems can occur on different scales: local, regional, orglobal. For example, your community may be discussing where tobuild a new landfill, or local property owners may be arguing withenvironmentalists about the importance of a rare bird or insect. Thedrinking water in your region may be affected by a polluted riverhundreds of miles away. Other environmental problems are global.For example, ozone-depleting chemicals released in Brazil maydestroy the ozone layer that everyone on Earth depends on.



� Lake Washington is now cleanenough for everyone to enjoy.

Po

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lati

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(in

bill

ion

s)

1600 1700 1800 1900 2000

Year

6.5

5.5

4.5

3.5

2.5

1.5

0.5

World Population: 1600–2000

Figure 11 � The human populationis now more than 10 times largerthan the population of 400 years ago.

at the time, Ellis successfully workedfor the passage of a bill in the statelegislature that set up committees tohandle projects of this kind. News-paper articles and letters to the edi-tor addressed the issue. Public forumsand discussion groups were also held.

The first sewage plant was con-nected in 1963. Today, the lake isclearer than it has been since scien-tists began their studies of the lakein the 1930s. The story of Lake

moving the sewage. Legislators andcivic leaders addressed the legalproblems. Volunteers, local media,and local activists provided publiceducation and pressed to get theproblem solved quickly. The clear,blue waters of Lake Washingtonstand as a monument to citizens’desires to live in a clean, healthyenvironment and to their ability towork together to make it happen.

CRITICAL THINKING

1. Analyzing Processes Explainhow each person and group playeda crucial role in the cleanup of LakeWashington.

2. Analyzing Relationships Howwas the scientists’ work similar tothe work of the Keene High Schoolstudents you read about in thissection?

Washington is an example of howenvironmental science and publicaction work together to solve envi-ronmental problems. Science wasessential to understanding a healthylake ecosystem, to documentingchanges that were beginning tocause problems, and to making pre-dictions about what would happenif changes were made or if nothingwas done. Engineers offered practi-cal solutions to the problem of

Population Growth: A Local Pressure One reason many environ-mental problems are so pressing today is that the agricultural rev-olution and the Industrial Revolution allowed the humanpopulation to grow much faster than it had ever grown before.The development of modern medicine and sanitation also helpedincrease the human population. As shown in Figure 11, thehuman population almost quadrupled during the 20th century.Producing enough food for such a large population has environ-mental consequences. In the past 50 years, nations have used vastamounts of resources to meet the world’s need for food. Many ofthe environmental problems that affect us today such as habitatdestruction and pesticide pollution are the result of feeding theworld in the 20th century.

There are many different predictions of population growth forthe future. But most scientists think that the human populationwill almost double in the 21st century before it begins to stabi-lize. We can expect that the pressure on the environment willcontinue to increase as the human population and its need forfood and resources grows.


What Are Our Main Environmental Problems?You may feel as though the world has an unlimited variety ofenvironmental problems. But we can generally group environ-mental problems into three categories: resource depletion, pollu-tion, or loss of biodiversity.

Resource Depletion Any natural material that is used byhumans is called a Natural resources can beclassified as renewable and nonrenewable as shown in Table 2. Arenewable resource is a resource that can be replaced relativelyquickly by natural processes. Fresh water, air, soil, trees, andcrops are all resources that can be renewed. Energy from the sunis also a renewable resource. A nonrenewable resource is aresource that forms at a much slower rate than the rate that it isconsumed. The most common nonrenewable resources are miner-als and fossil fuels. Once the supply of a nonrenewable resourceis used up, it may take millions of years to replenish it.

Resources are said to be depleted when a large fraction of theresource has been used up. Figure 12 shows a mine where copper,a nonrenewable resource, is removed from the Earth’s crust.Some renewable resources can also be depleted. For example, iftrees are harvested faster than they can grow naturally in an area,deforestation will result.

Pollution One effect of the Industrial Revolution is that societiesbegan to produce wastes faster than the wastes could be disposedof. These wastes accumulate in the environment and cause pollu-tion. is an undesired change in air, water, or soil thatadversely affects the health, survival, or activities of humans or

Pollution

natural resource.


Figure 12 � More than 12 milliontons of copper have been minedfrom the Bingham mine in Utah.Once all of the copper that can beprofitably extracted is used up, thecopper in this mine will be depleted.

Renewable and Nonrenewable Resources

Renewable Nonrenewable

energy from the sun

water

wood

soil

air

metals such asiron, aluminum,and copper

nonmetallic ma-terials such as salt,sand, and clay

fossil fuels

Table 2 �

QuickLABClassifying ResourcesProcedure1. Create a table similar to Table 2.2. Choose five objects in your

classroom, such as a pencil, anotebook, or a chair.

3. Observe your objects closely,and list the resources that com-prise them. For example, a pen-cil is made of wood, graphite,paint, aluminum, rubber, andpumice.

4. Classify the resources you haveobserved as nonrenewable orrenewable.

Analysis1. What percentage of the resources

you observed are renewable?What percentage of theresources are nonrenewable?

2. Hypothesize the origin of threeof the resources you observed.If time permits, research the ori-gin of the resources you choseto find out if you were correct.


other organisms. Much of the pollution that troublesus today is produced by human activities. Air pollu-tion in Mexico City, as shown in Figure 13, is danger-ously high, mostly because of car exhaust.

There are two main types of pollutants. Biode-gradable pollutants are pollutants that can be brokendown by natural processes. They include materialssuch as human sewage or a stack of newspapers.Degradable pollutants are a problem only when theyaccumulate faster than they can be broken down.Pollutants that cannot be broken down by naturalprocesses, such as mercury, lead, and some types ofplastic, are called nondegradable pollutants. Becausenondegradable pollutants do not break down easily,they can build up to dangerous levels in the environment.

Loss of Biodiversity The term refers to the num-ber and variety of species that live in an area. Earth has beenhome to hundreds of millions of species. Yet only a fraction ofthose species are alive today—the others are extinct. Extinction isa natural process, and several large-scale extinctions, or massextinctions, have occurred throughout Earth’s history. For exam-ple, at the end of the Permian period, 250 million years ago, asmuch as 95 percent of all species became extinct. So why shouldwe be concerned about the modern extinction of an individualspecies such as the Tasmanian tiger shown in Figure 14?

The organisms that share the world with us can be considerednatural resources. We depend on other organisms for food, forthe oxygen we breathe, and for many other things. A species thatis extinct is gone forever, so a species can be considered a nonre-newable resource. We have only limited information about howmodern extinction rates compare with those of other periods inEarth’s history. But many scientists think that if current rates ofextinction continue, it may cause problems for human popula-tions in the future. Many people also argue that all species havepotential economic, ecological, scientific, aesthetic, and recrea-tional value, so it is important to preserve them.

biodiversity


1. Explain how hunter-gatherers affected the environ-ment in which they lived.

2. Describe the major environmental effects of theagricultural revolution and the Industrial Revolution.

3. Explain how environmental problems can be local,regional, or global. Give one example of each.

4. Identify an example of a natural source of pollution.

CRITICAL THINKING5. Analyzing Relationships How did the Industrial

Revolution affect human population growth?

6. Making Inferences Fossil fuels are said to be non-renewable resources, yet they are produced by theEarth over millions of years. By what time frame arethey considered nonrenewable? Write a paragraphthat explains your answer. WRITING SKILLS

S E C T I O N 1 Review

Figure 14 � The Tasmanian tigermay be the only mammal to becomeextinct in the past 200 years on theisland of Tasmania. During the sameperiod of time, on nearby Australia,as much as 50 percent of all mam-mals became extinct.

Figure 13 � The problem of air pol-lution in Mexico City is compoundedbecause the city is located in a valleythat traps air pollutants.


science and the environment chapter · 2020-03-31 · many fields of study environmental science is...

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