Also covers: Academic Standards 1, 2, 5 (Detailed ...

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sections

1 Energy Resources

2 Alternative Energy Resources

3 WaterLab Using Water

4 LandLab Using Land

Virtual Lab How much electricityis used in a house?

Resources You UseWhen you toast a piece of bread for break-fast, do you realize that the bread started outas grains of wheat? What water source isused to irrigate the wheat fields? In thischapter you’ll learn more about Earth’sresources.

Where does the energy used to runthe farm equipment for this farm come from?Science Journal

Resources

Academic Standard—3: Students collect and organize data to identify relationships betweenphysical objects, events, and processes. They use logical reasoning to question their own ideasas new information challenges their conceptions of the natural world.

Also covers: Academic Standards 1, 2, 5 (Detailed standards begin on page IN8.)

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Resources Make the followingFoldable to help you illustratethe advantages and disadvan-tages of renewable and nonre-newable resources.

Fold a verticalsheet of paper inhalf from top tobottom.

Fold in half fromside to side withthe fold at the top.

Unfold the paperonce. Cut only thefold of the top flapto make two tabs.

Turn the papervertically anddraw on the fronttabs as shown.

Illustrate and Label Before you read the chap-ter, write what you know about the advantagesand disadvantages of using nonrenewableresources and renewable resources. As you readthe chapter, list advantages and disadvantagesfor each type of resource discussed in the chapter.

STEP 4

STEP 3

STEP 2

STEP 1

Observe Solar EnergyDo you know that you use resources 24 h perday? Even when you are asleep, resources areused to power streetlights and heat yourhome. Where do humans get the resources tomeet their energy needs? Sometimes peopleharness energy from wind, water, and the Sun.

1. Get two empty tin cans from your teacher.Paint the outside of one can black or wrapit in black construction paper. Paint theoutside of the other can white or wrap itin white construction paper.

2. Fill both cans with cool tap water. Recordthe temperature of the water in each can.Don’t use a mercury thermometer.

3. Tape a piece of black construction paperover the top of the black can. Tape a piece ofwhite construction paper over the top of thewhite can. Place both cans in direct sunlight.

4. After an hour, record the temperature ofthe water in both cans.

5. Think Critically Which had the greaterincrease in temperature—the water inthe black can or the water in the whitecan? How does the color of an object affectthe way it absorbs the Sun’s energy?

Start-Up Activities

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NonrenewableResources

RenewableResources

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Generating EnergyDoes your day start like this? You wake up to the BEEP-BEEP

of the alarm clock. You switch on the light and stumble towardthe bathroom. You take a hot shower, then head back to yourbedroom to dress. You flip on the radio to hear the weatherreport so you know what to wear. Your day has hardly begun andalready you’ve used electricity at least four times. Have you everwondered where your electricity comes from?

Fossil Fuels In the United States, electrical power plants arethe main sources of energy for homes and factories. Energy isthe ability to change things, such as the temperature, speed, ordirection of an object. When energy is used to change things,energy itself often changes from one form to another. Wood, forinstance, contains chemical energy. As wood is burned, itschemical energy is changed into heat and light energy. Mostpower plants produce electricity by burning fossil fuels. A fossilfuel is an energy resource formed from the buried remains ofancient plants and other organisms. Coal, oil, and natural gasare examples of fossil fuels. Next you will take a closer look athow these important energy resources are formed.

■ Describe the advantages and dis-advantages of using fossil fuels.

■ Identify nonrenewable resources.

Energy resources provide theelectricity you use.

Review Vocabularygeologist: scientist who studiesEarth’s surface and interior

New Vocabulary

• fossil fuel

• pollution

• acid rain

• nonrenewable

Energy Resources

Figure 1 Coal is formed fromthe remains of ancient swampvegetation.

Over time, dead vegetation accumulated inswamps and was converted to peat.

The peat was covered by layers of sediment.Heat and pressure caused the peat to form intoa solid layer of lignite coal.

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SECTION 1 Energy Resources 287

Coal The coal people use today began to form millions ofyears ago in swampy regions where huge, fernlike plants grew inabundance. When the plants died and fell into the swamp, theywere covered by sediment such as mud, sand, and other deadplants. Layer upon layer of sediment piled up. Over time,microorganisms changed the plant material into a dark, organicsubstance called peat. The weight of sediment pressed down onthe peat. Burial and decay generated heat. The combination ofheat and pressure changed the buried material into a soft, browncoal called lignite. Over time, more and more layers of sedimentpiled on top of the lignite, and further changes occurred in thecoal, as shown in Figure 1.

Oil and Natural Gas Most geologists agree that oil and nat-ural gas form over millions of years from the partial decay ofalgae and other microscopic ocean organisms called plankton.The process begins when these organisms die and fall to theseafloor. Over long periods of time, these decaying organismsaccumulate in ocean sediment. Eventually, thick layers of sandand mud are deposited over the partially decayed organisms inthe same way that coal is buried by sediment. As with coal, thecombination of pressure and heat causes chemical reactions tooccur. The buried material eventually forms the liquid youknow as oil and the gases known as natural gas.

When layers of bituminous coal were severelycompressed and heated by forces withinEarth, the layers changed into anthracitecoal—the hardest of all coals.

More layers of sediment piled up on top ofthe lignite and compressed it even further.Temperatures increased, and lignite becamebituminous coal.

Black Lung Disease Blacklung, a disease that causesdamage to the lungs,results from long-terminhalation of coal dust.Before the effects of inhal-ing coal dust were known,coal miners worked unpro-tected in mines, breathingin high amounts of dust.Find out more informationabout black lung, theconditions miners used towork in, and what preven-tative measures are usedin coal mines today.Record what you find outin your Science Journal.

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Impermeable rock

Water inpermeable rock

Natural gas Oil

Natural gas

Oil

Impermeable rock

Oil


Finding Oil and Natural Gas Once oil and natural gas haveformed, they will begin to move upward because they are lessdense than both the surrounding rock and the water containedwithin small spaces in the rock, called pores. At some point theoil and natural gas might reach a barrier of impermeable rockand become trapped. Because natural gas is even less dense thanoil, it usually is found above oil, as shown in Figure 2.

Pollution and Fossil FuelsFossil fuels are important resources. However, when they are

burned to produce energy, environmental problems can occur.When fossil fuels are burned in cars, power plants, homes, andfactories, gases such as nitrogen oxide and sulfur oxide and tinybits of soot and dust are released into the air. These substancescontribute to pollution. Pollution is harmful waste products,chemicals, and substances found in the environment.

Air pollution can make your throat feel dry or your eyessting. Many people have trouble breathing when air pollutionlevels are high. For the elderly and people with lung or heartproblems, air pollution can be deadly. In the United States,about 60,000 deaths each year are linked to air pollution.

People aren’t the only living things that are harmed by air pol-lution. Acid rain is produced when gases released by burning oiland coal mix with water in the air to form acidic rain or snow.When acid rain reaches the soil, the growth of plants and trees isaffected and many die. As pollution levels increase, the ability ofthe environment to support different life-forms suffers.

Spare the Air Reducing the number of pollutants releasedinto the air is easier than cleaning pollutants from the air. Today,cars have catalytic converters, shown in Figure 3, that reduce theamount of pollutants released.

Figure 3 Catalytic converterswork by converting pollutants intoless harmful compounds.

Figure 2 Engineers drill throughlayers of rock to reach undergrounddeposits of oil and natural gas.Explain why oil and natural gasmove upward.

Catalyticconverter

Less-harmfulemissions

Vehicleexhausts

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SECTION 1 Energy Resources 289

Are fossil fuels running out?Problems with fossil fuels aren’t limited to pollution alone. If

the population continues to grow or if the average consumptionof energy increases per individual, then the demand for energywill increase. People could find themselves running out of theseenergy resources in the future. Remember that the process offossil fuel formation can take millions of years. The amount offossil fuels that are in Earth now have been there for a long time.Plants and other organisms that die today won’t become fossilfuels for millions of years. Are people using fossil fuels fasterthan they are being replaced? Consider the problem and try todevelop some of your own solutions.

Calculate Savings

1. What would be the savings for each driver if a third driver joined the carpool?

2. What would be the savings for each driver if the cost of gasoline and maintenanceincreased to 25 cents?

CAR POOL BENEFITS Sally and Tania each drive 60 km round-trip to work five days a week,50 weeks a year. Gasoline and maintenance cost 20¢/km. How much money could eachdriver save yearly if they carpooled?

SolutionThis is what we know:

This is what we need to find out:

This is the procedure you need to use:

Check your answer: Divide the cost per year of driving by the cost per kilo-meter. $3,000/year � $0.2/km � 15,000 km

● Total distance per person � 60 km/day �

5 days/week � 50 weeks/year � 15,000 km/year

● Total cost per person � 15,000 km/year �$0.2/km � $3,000/year

● Cost if carpooling � $3,000/year � 2 � $1,500/year

● Savings per person � $3,000/year � $1,500/year �$1,500/year

What is the savings for each person per year if they arecarpooling?

● Distance per person � 60 km per day

● Cost per person � 20¢ or 0.2 dollars per km

For more practice, visit in6.msscience.com/math_practice

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Self Check1. Classify Why is coal a nonrenewable resource?

2. Describe the disadvantages of using fossil fuels.

3. Explain how acid rain forms. Why is it harmful?

4. Explain why coal, oil, and natural gas are called fossilfuels.

5. Think Critically Why are you likely to find natural gasand oil deposits together, but less likely to find coaldeposits at the same location?

SummaryGenerating Energy

• Most power in the United States is generatedby the burning of fossil fuels.

• Coal, natural gas, and oil are types of fossilfuels.

Pollution and Fossil Fuels

• Fossil fuels give off nitrogen oxide, sulfuroxide, soot and dust when they are burned.

• Acid rain forms when fossil fuels are burned.

• Some governments are trying to reduce theamount of pollution from burning fossil fuels.

Are fossil fuels running out?

• Fossil fuels are nonrenewable resources—they aren’t replenished at the same rate asthey are used.

6. Use Proportions The United States has 5,630 carsfor every 10,000 people. The population of the UnitedStates is about 276 million. How many cars are in the United States?

Nonrenewable Resources If you answered yes tothe question on the previous page, you’re right. Someenergy resources are being used faster than naturalprocesses can replace them. Resources that cannot bereplaced by natural processes in less than about 100 yearsare nonrenewable. Fossil fuels are nonrenewable. Thismeans that humans could run out of these importantsources of energy someday. The question is when.

Why are fossil fuels considered to benonrenewable?

How much is left? At current levels of usage, coal providesabout 26 percent of the world’s energy needs, and oil and natu-ral gas provide almost 64 percent. As Figure 4 shows, scientistsestimate that there are enough coal reserves to last 200 to 300years at present rates of usage. The available reserves of oil couldbe used up within 30 to 40 years. It is estimated that natural gasreserves will last about 60 more years.

How can this problem be solved? Conserving electricityhelps reduce the use of fossil fuels. It also helps reduce pollution.Can you think of other ways to help? For example, you can useother energy resources in addition to fossil fuels to meet yourenergy needs. In the next section, you’ll learn about alternativesources of energy that can be used again and again.

Figure 4 This graph showsavailable reserves of coal, oil, andnatural gas.Evaluate What might you do athome to help reduce the use of fossilfuels?

in6.msscience.com/self_check_quiz

Reserves of Coal, Oil,and Natural Gas

200

250

100

50

150

0

300

Natural resource

Tim

e (y

ears

)

Coal Oil Naturalgas

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Other Sources of Energy When you sit in the Sun, walk in the wind, or row against a

river’s current, you are feeling the power of resources that can beused to meet your energy needs. But unlike fossil fuels, the Sun,wind, and water are energy resources that can be used again andagain. They are constant—the Sun has shone for billions ofyears and will shine for billions more. Energy resources that canbe recycled or replaced by natural processes in less than about100 years are considered renewable. Some renewable energyresources include the Sun, wind, water, and geothermal energy.

Solar EnergySuppose you’re a scientist trying to find a single source of

energy to meet all the world’s needs. You might look to the Sun fora solution. Energy from the Sun is renewable, and it doesn’t causepollution. Plus, enough energy from the Sun reaches Earth in anhour to supply all the energy the world uses in one year. Currently,we do not have the technology to harness all of the Sun’s energy.But we do use energy from the Sun, called solar energy, for manythings. One example is shown in Figure 5. This towering structureof flat mirrors is located outside the town of Odeillo, France. Themirrors are positioned to focus energy fromthe Sun on one part of the tower. The heatis used to run a solar furnace inside thetower, where temperatures can reach ashigh as 3,300°C. Figure 6 shows how solarenergy, through the use of solar panels, canbe used to generate electricity.

Alternative EnergyResources

■ List different kinds of renewableresources.

■ Describe the advantages anddisadvantages of using alterna-tive energy resources.

Many alternative sources of energyare renewable.

Review Vocabularytechnology: application ofscience to help people

New Vocabulary

• renewable

• solar energy

• hydroelectric power

• geothermal energy

• nuclear energy

Figure 5 The mirrors on this tower in Francecollect energy from the Sun. The solar furnace pro-vides the high temperatures necessary for sometypes of research.Explain how this building is being used for solarenergy.

291

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VISUALIZING SOLAR POWER PLANTS


Sunlight is a clean, limitless energy source. But it must be converted to another form—such as electricity—to be useful. As shown here,

solar power plants use mirrors to concentrate the Sun’srays to heat a liquid, in this case a molten nitrate salt.The hot liquid, in turn, is used to generate electricity.

Receiver

Liquidbeingheated

Hot liquidstorage

Cold liquidstorage

Pipes fromreceiver

Pipes to receiver

CENTRAL RECEIVING TOWERA liquid then is circu-lated through thereceiver and heatedby the concentratedsolar energy to morethan 500°C.

B

HELIOSTAT ARRAY A solar powerplant such as this one in San BernardinoCounty, California, has a nearly circulararray of curved mirrors called heliostats.The heliostats track the Sun and focusits rays on a central receiver mountedon a tower.

A

HEATED LIQUID The hot liquid then can be used to make steam.The steam drives a turbineconnected to an electricity-producing generator.Alternatively, the liquid can be stored to producesteam—and electricity—at a later time.

C

Figure 6

(b)James Pacheco, (others)Joe Flores/DOE/NREL

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SECTION 2 Alternative Energy Resources 293

Solar Cells Other types of solar-energy technology aremuch simpler than the example shown in Figure 6. For instance,you might have used a solar calculator to complete your home-work assignments. Solar calculators, such as the one shown inFigure 7, are powered by solar cells, which collect light andchange it into electricity. In a solar cell, thin layers of silicon—ahard, dark-colored element—are sandwiched together andattached to tiny wires. As light strikes the different layers, it pro-duces an electric current. On a larger scale, solar cells are used tosupply electricity to remote areas. They also provide the powerfor the call boxes on the highways of North America. Solar cellsare expensive and, to date, they have not been developed forwidespread use.

Is solar energy the answer? Nonpolluting, renewable,and abundant—solar energy sounds like a wonderful way togenerate energy, doesn’t it? So why don’t people rely on solarenergy to meet all of their energy needs? Solar energy has someserious drawbacks. It’s available only when the Sun is shining, sosolar cells can’t work at night. In addition, different parts ofEarth receive different amounts of solar energy. If you live in anarea that is cloudy much of the time, it’s doubtful that solarenergy can meet all of your energy needs because solar cellswork less efficiently on cloudy days. At this point, scientistsdon’t have the technology to harness and store effectively anadequate amount of the Sun’s vast energy. Until that time, somescientists think that the best solution to energy problems mightbe to use fossil fuels and solar energy in combination with otherenergy sources. You’ll read about these next.

What is one problem with solar energy use?

Figure 7 The panels, car, andcalculator shown here receive theirpower from the Sun.Define What are solar cells?

(l)Martin Bond/Science Photo Library/Photo Researchers, (r)William J. Weber/Visuals Unlimited

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Energy from WindImagine this. Outside, the sky is a clear shade of blue and the

wind scatters fallen leaves across the street. Inside, a kite hangsin your closet. Can you think of a good way to spend the day?

A windy day is perfect for flying a kite. A strong wind can lifta kite high in the sky and whip it all around. When you fly a kite,you use energy from the wind. Energy from wind was and still isused to send sailboats skimming across the ocean. In the pastwindmills used wind energy to grind corn and pump water. Thefirst large-scale use of wind energy was developed in Vermontduring World War II. Today windmills are used to generate elec-tricity worldwide. In the United States, regions of the Northeast,the Midwest, the Great Plains, and the West have been identifiedas having wind conditions best suited to using wind power.European countries such as Denmark and Finland also use windpower to their advantage. When a large number of windmills areplaced in one area for the purpose of generating electricity, thearea is called a wind farm. Figure 8 shows a wind farm inCalifornia.

Like all forms of energy, energy from the wind has advan-tages and disadvantages. Wind is nonpolluting. It does not harmthe environment or produce waste. However, only a few regionsof the world have winds strong enough to generate electricity ona large scale. Also, wind isn’t steady. Sometimes it blows toohard, and sometimes it stops altogether.

Energy Usage at HomeEnergy usually is measuredin units called joules.Another unit used toexpress energy is thekilowatt-hour. One kilo-watt-hour is equal to3,600,000 joules. Find outhow many kilowatt-hoursof energy are used in yourhome in a month’s time.

Figure 8 This wind farmin California uses energyfrom the wind to generateelectricity.Evaluate the pros andcons of energy from winds.

Doug Sokell/Visuals Unlimited

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Figure 9 Water in the reservoiris released through gateways intopipes near the base of the dam.Explain why people have builtdams.

Reservoir

Generator

Dam

Turbine

The pipes lead to the turbines. Because of the weight of thewater in the reservoir, the water in the pipes is under greatpressure as it falls to the turbines.

The pressure of the water turns the turbinesthat drive the electric generators in theplant.

Hydroelectric PowerIf you’ve ever watched a river flow, you’ve seen an energy

resource in action. Energy from moving water also can generateelectricity. The production of electricity using water is calledhydroelectric power. People in southern Canada and the easternUnited States use the water in Niagara Falls to generate hydro-electric power for a number of large cities. In other places thathave no natural waterfalls, people have built concrete dams toproduce hydroelectricity. The Shasta Dam on California’sSacramento River is one of the tallest structures of its type in theworld. What happens to water of the Sacramento River behindthe dam?

The river water that backs up behind a dam creates a reservoir,or large reserve, of water. Many reservoirs are big enough to be con-sidered lakes. Lake Shasta, the reservoir created by the dam on theSacramento River, is 56 km long. Look at Figure 9 to see how a damand a hydroelectric power plant work to generate electricity.

Hydroelectric Power Problems Like solar power andenergy from the wind, hydroelectric power doesn’t cause pollu-tion and it’s renewable. But this energy resource has its prob-lems. When dams are built, the reservoir located behind the damcan fill with sediment, and increased erosion can occur down-stream. Land above the dam is flooded and wildlife habitats aredisturbed. In addition, dams and power plants already havebeen built near most rivers suitable for generating hydroelec-tricity. Other places can’t use hydroelectric power becausethey’re not located near flowing water.

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Figure 10 Geysers, such asthis one in New Zealand, eruptbecause of geothermal energy.Define geothermal energy.

Energy from Earth Another renewable energy resource exists beneath

Earth’s surface near bodies of hot, molten rock called magma.The heat from the magma and hot rock that surrounds it,called geothermal energy, can be used to generate electricity.Figure 10 shows a geyser in New Zealand that erupts because ofgeothermal energy. A geyser forms when groundwater is heatedby hot rocks and turns to steam. The steam, along with hotgroundwater, is forced up in powerful spurts through openingsin Earth’s crust. This is an effect of geothermal energy frommagma that is located close to Earth’s surface. People in Icelandand California use the hot water and steam from geysers to heattheir homes.

Sometimes magma is not found close to Earth’s surface, butengineers can drill wells to reach heated rock. Groundwater orwater injected into the rock then can turn to steam and rise toEarth’s surface. This rising steam is used to generate electricity.

How can geothermal energy be used to generateelectricity?

Geothermal Energy Problems As you’ve been learning, theuse of each type of energy resource has advantages and disadvan-tages. Geothermal energy is no exception. Using geothermalenergy can release hot, salty water at Earth’s surface, which can beharmful to nearby plants and animals. In addition, only a fewplaces have magma near Earth’s surface. To generate geothermalpower elsewhere, deep wells must be drilled. This process isexpensive and can disrupt natural habitats near the well.

Modeling the Effectsof HeatProcedure

1. Fill a glass beaker withcold water.

2. Fill a small, clear-plasticbottle nearly full of coldwater. Add several drops offood coloring to the bottle.

3. Carefully lower the smallbottle into the beaker sothat the bottle is uprightunderwater. Hold the bot-tle in place, if necessary.Observe what happens tothe colored liquid that isinside the bottle.

4. Repeat the experiment, butthis time fill the bottle withhot water. Observe whathappens to the colored liq-uid inside the bottle.

Analysis1. How did heat affect the

movement of the coloredliquid inside the bottle?

2. Changes in heat and pres-sure force hot water underEarth’s surface to rise. Howis the movement of thecolored liquid in the bottlesimilar to the movement ofhot water under Earth?How is it different?

Simon Fraser/Science Photo Library/Photo Researchers

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Nuclear EnergyAtoms are the basic units of matter, and each atom contains

a nucleus. All nuclei (singular, nucleus) have energy. Scientistshave found a way to extract energy from atoms. This is callednuclear energy. Nuclear energy is produced by splitting thenuclei of certain elements. In this process, known as fission,energy is released. The energy is used to change water intosteam. The steam then is used to drive a turbine and generateelectricity for homes and industries, as shown in Figure 11.

The most commonly used fuel in nuclear power plants isuranium. Uranium has a nucleus that can be split easily. Onceuranium ore is mined, it’s refined and placed in long, metalpipes called fuel rods. The fuel rods sit in a pool of cooling waterwithin a nuclear reactor. Energy is released when neutrons givenoff by the uranium split the nuclei of other uranium atoms,which in turn release more neutrons and more energy. Thisprocess is known as a chain reaction.

Nuclear Energy Problems Nuclear energy produces morethan electricity. It also produces highly radioactive nuclearwaste. This waste contains materials that can cause cancer orhave other harmful effects on living things. Some of the wastewill remain radioactive for more than 10,000 years. Nuclearwaste must be handled and stored carefully to keep it fromharming living things and from entering the environment.Nuclear fuels are also nonrenewable. As you might have guessed,these are major drawbacks in using nuclear power.

Figure 11 Heat energy is gen-erated by fission within the nuclearreactor. This heat is used to changewater into steam. The steammoves the turbine, which is con-nected to a generator that pro-duces electrical energy.

Containment building

Nonradioactive waterTurbine

Steamgenerator

Pump

Radioactive water Steam condenser

Coolingwater

Reactor

Topic: Nuclear energyVisit in6.msscience.com for Weblinks to information about nuclearenergy.

Activity Generate a list of prosand cons about the use of nuclearenergy.

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Self Check1. Compare and contrast a renewable resource and a

nonrenewable resource.

2. Summarize some advantages and disadvantagesof solar energy, wind energy, and hydroelectricenergy.

3. Infer What are some disadvantages of geothermalenergy and nuclear energy?

4. Think Critically A well is drilled into hot rock to pro-duce electricity. Describe the different steps in thisprocess and explain how energy changes from one formto another during this process.

SummarySolar Energy

• Solar energy is a renewable resource.

• Solar cells already are in use in some technology.

Energy from Wind

• Windmills generate electricity in some areas.

Hydroelectric Power

• Energy from moving water can generateelectricity.

• Dams are built to establish a reservoir of water.

Energy from Earth

• Geothermal energy comes from the heat ofmagma within Earth.

Nuclear Energy

• Nuclear energy is created during fissionreactions.

• Nuclear waste also is generated during fission.

5. Predict The world’s energy demands are increasing.Oil could be depleted within 50 years. How do youthink the use of alternative energy resources will change in your lifetime?

Nuclear Energy Use Because of potential problemsin storing nuclear waste, nuclear energy has seen limiteduse in the United States. Electricity generated fromnuclear power makes up only eight percent of the totalenergy used in the United States. Worldwide, about 30countries use nuclear energy to generate electricity.Countries such as France and Japan lead the world innuclear energy use. Almost 80 percent of France’s energyneeds are met by nuclear power.

Currently, the use of nuclear energy and renewableenergy resources is limited. But improvements in tech-nology might enable these resources, particularly theSun, to be major sources of energy in the future.

Energy Use In 1998, the United States met eighty-fivepercent of its energy needs using fossil fuels. Figure 12 shows thepercentage of energy obtained from different sources in the UnitedStates. These numbers closely match global percentages of usage ofnonrenewable and renewable energy resources. Ninety percent ofthe world’s energy is supplied by fossil fuels. Nuclear and hydroelec-tric power provide seven percent and three percent of world energyneeds, respectively. That leaves less than one percent for the remain-ing sources of energy—solar, geothermal, and wind combined.


Energy Use in the United States, 1998

Geothermal,wind, and solar

0.5%

Other3%

Coal23%

Oil39%

Naturalgas

23%

Nuclear8%

Hydroelectricpower3.5%

Figure 12 The use of differentenergy sources in the United Statesis shown above.Interpret Data What percentageof energy came from fossil fuels?

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SECTION 3 Water 299

Water—A Vital ResourceEarth has a vast amount of water. In fact, about 70 percent of

Earth is covered by water. This water continually moves throughthe water cycle, which is shown in Figure 13. Water helps shapeEarth’s surface through the processes of erosion and deposition.Most importantly, water is needed by all living organisms to stayalive. Without water, living organisms could not carry outimportant life processes, such as growth and waste removal.Water could be Earth’s most valuable resource. That’s why it’simportant to know how much water is available and where itcomes from.

Usable Water Only a small portion of Earth’s water is avail-able for use by humans. Approximately 97 percent of the world’stotal water supply is salt water in the oceans. That leaves onlythree percent in the form of freshwater, and more than three-fourths of that is frozen in glaciers and ice caps. Thus, lessthan one percent of Earth’s total water supply is available forhumans to use. This small percentage is found underground orin lakes, streams, and rivers.

Water

■ Explain how important water isto living things.

■ Identify different sources ofwater.

■ Describe how the location ofwater affects where humans live.

When water becomes polluted, itaffects all living things.

Review Vocabularymicroorganisms: a many- orone-celled organism too small tobe seen without magnification

New Vocabulary

• groundwater

• point source pollution

• nonpoint source pollution

Runoff

Groundwater

Evaporation

Precipitation

Condensation

Figure 13 All living things needclean water to survive.

The water cycle shows how watermoves through the atmosphere andreturns to Earth’s surface.

Standard—6.3.8: Explain that fresh water, limited in supply and uneven in distribution, is essential for life andalso for most industrial processes. Understand that this resource can be depleted or polluted, making itunavailable or unsuitable for life.

Also covers: 6.1.7, 6.2.6, 6.2.7, 6.3.7 (Detailed standards begin on page IN8.)

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GroundwaterWhen you turn on a faucet, water

flows out. Where does this water comefrom? One major source of freshwater isgroundwater that lies under Earth’s sur-face. Groundwater is water that soaksinto the ground and collects in smallspaces between bits of soil and rock, asshown in Figure 14. If the small spacesare connected, the water can flowthrough layers of rock and soil. Peopledrill down into these layers to makewells. They then pump the water to thesurface for use as drinking water, in fac-tories, and in agriculture.

What is ground-water?

In the United States, groundwater provides 40 percent ofpublic water supplies. Industries and farms also use groundwa-ter. In many agricultural areas, groundwater is the only source ofwater available. Is this important resource renewable or nonre-newable? Some people consider groundwater renewable becauseit is part of the water cycle, which recycles water constantly.However, it takes a long time for groundwater to move throughrock layers. Therefore, it can take a long time to clean ground-water if it becomes polluted. Because of this, clean, usablegroundwater should be considered a nonrenewable resource.

Surface Water Not all places get their water from under-ground. Surface water comes from streams, rivers, ponds, lakes,and reservoirs—it’s the water you can see easily on Earth’s sur-face. Do you use surface water or groundwater to meet yourwater needs? If you don’t know, find out. Ask your teacher oranother adult, or check with your city water department.

Water Use Your body needs water to survive, but people alsodepend on water for recreational uses such as swimming andfishing. People also need water to bathe and cook food.

Water is used by industries to manufacture products. Boatsare used to transport these products and people across oceans oralong rivers. Farmers use water to irrigate crops.

Many plants and animals live in oceans, lakes, or rivers. Theyspend their entire lives in water. What do you think would hap-pen to these living things if the water they live in were polluted?

Indiana Academic

Standard Check

6.3.8: Explain that fresh water …can be depleted or polluted, mak-ing it . . . unsuitable for life.

Why is groundwaterdescribed as a nonrenewableresource?

Figure 14 Groundwater is foundunder Earth’s surface in small spacesbetween bits of soil and rock.

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SECTION 3 Water 301

This oil spill, the dark color leaking from the tanker,could threaten marine organisms and nearby beaches.

Water PollutionHave you ever seen water in the same condition as the water

shown in Figure 15? The chemicals found in the water are anexample of water pollution. Water pollution occurs when harm-ful debris, chemicals, or biological materials are added to water.These pollutants lower its quality. Some pollution comes from asingle, identifiable source and is called point source pollution.If an oil tanker such as the one shown in Figure 15 begins leak-ing, a skim of oil is released into the sea and pollutes the waterdirectly. You can see the pollution occurring. Have you ever seenexamples of this type of pollution near your home or school?

Most types of pollution are hard to trace to a single source.Nonpoint source pollution is pollution that cannot be tracedback to an exact location. Nonpoint sources can be industries,homes, or farms. How can a farm pollute water? Chemical fer-tilizers are used to increase crop yields. These fertilizers enterstreams, lakes, and wetlands where they can damage the envi-ronment. Some of these chemicals seep into the ground and canpollute groundwater supplies. Can you think of any way thatyou might cause water pollution? If you spill gasoline in yourdriveway, the gasoline will be carried away by runoff. It can enterthe city sewage system or a stream and eventually make its wayinto a drinking water supply.

Why is the origin of nonpoint source pollutiondifficult to trace?

This water was polluted by the addition ofindustrial wastes.

Figure 15 Water pollution cancause serious problems.

Topic: Water PollutionVisit in6.msscience.com for Weblinks to information about waysto reduce water pollution.

Activity Create a list of specificways your community can protect alocal water source from pollution.

(l)Simon Fraser/Science Photo Library/Photo Researchers, (r)The Telegraph Colour Library/Getty Images

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Cleaning Up WaterMany countries are working together to reduce the amount of

water pollution. For example, the United States and Canada coop-erate to clean up the pollution in Lake Erie, which borders bothcountries. The U.S. government also has passed several laws tokeep water supplies clean. The Safe Drinking Water Act is a set ofgovernment standards designed to ensure safe drinking water. TheClean Water Act gives money to states to build water-treatmentplants, such as the one shown in Figure 16. Water is cleaned atsuch plants before being used for drinking and other purposes.

Water Purification In the first stage of water purification,water is run through a settling basin. Large particles of sedimentsettle out. Smaller particles are filtered out by sand and gravel.Water then is pumped into a tank where chemicals are added tokill microorganisms. In most water-purification plants, chlorineis used to treat the water. Some treatment plants use alternativemethods such as exposing the water to ultraviolet light to dis-infect it. After it has been purified, the clean water is pumped to consumers.

Water DistributionAs you have learned, water is vital to the survival of all living

things. Take a look at the map shown in Figure 17. Do you see arelationship between the location of major centers of popula-tion and major bodies of water? People usually build cities nearshorelines and along large rivers. As you can see from the map,desert areas generally don’t support large populations.

Figure 16 Water is made safefor drinking at water-purificationplants such as the one shown here.Infer what would happen if therewas no safe water to drink.

Storage tanksto consumer

Pumping station

4.Water is pumped toconsumers or stored.

Storage tanks toconsumers

Pumping station

3.Water is chemicallytreated to disinfect it.

2.Water is filtered bysand and gravel.

1.Solids are allowedto settle in a holding tank.

Observing How WaterIs CleanedProcedure

1. Fill a clean, empty glass jartwo-thirds full of water.

2. Add a scoop of soil tothe jar.

3. Put the lid on the jar, closeit tightly, and then shakethe jar until the waterbecomes muddy.

4. Put the jar aside and let itstand for two days.

Analysis1. What happened to the soil

in the jar? What happenedto the water?

2. Which part of the water-purification process didyou model? Which types ofimpurities would not beremoved by the processesmodeled in this activity?

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SECTION 3 Water 303

Self Check1. Explain why water is such a valuable resource. What

would happen if water was not available?

2. Describe how humans use water.

3. Explain What is the difference between point sourceand nonpoint source pollution?

4. Think Critically Some cities are located near desertareas. How do you think they might meet theirdemands for water?

SummaryWater—A Vital Resource

• 70 percent of Earth is covered in water.

• 97 percent of that water is salt water.

• Less than 1 percent is usable to humans.

Groundwater

• One source of freshwater is the water underEarth’s surface.

• Water is used for recreation, survival, indus-try, and farming.

Water Pollution

• Pollution can come from point sources or non-point sources.

Cleaning Up Water

• Laws have been set up to keep water clean.

5. Use a Database Visit in6.msscience.com for Web links toinformation about the Clean Water Act. Write a sum-mary of how this legislation supports water-quality

standards in the United States.

Managing Water Resources Recall that less than one per-cent of Earth’s water is available for human use. In an effort tobetter manage water resources many countries have passed lawsto reduce water pollution and to monitor the quality of thewater supply. Water is a valuable resource, necessary for the sur-vival of organisms as well as for use in everyday life. It is everybit as valuable as the energy resources you studied earlier. Next,you will read about another important resource—land.

Figure 17 This map shows thatmost of the world’s population iscentered around large bodies ofwater. The darker areas indicatedensely populated regions. Thedarker the area is, the more densethe population is.


Los Angeles

Mexico City

São Paulo

Caracas

ChicagoLondon Berlin

RomeMadrid

Kinshasa Jakarta

Sydney

Bangkok

Beijing

Guangzhou

Tehran

Moscow

Delhi

Bombay

Cairo

SingaporePACIFIC OCEAN

PACIFICOCEAN

ATLANTICOCEAN

INDIANOCEAN

Buenos Aires

TokyoSeoulNew York

Densely populated regions

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Water is an important resource that you use every day. The average person in the UnitedStates uses about 626 L of water each day. Dothis lab to see how much water you and yourfamily use.

Real-World QuestionHow much water does your family use inthree days?

Goals■ Calculate the amount of water used in your

household in three days.■ Make a plan to reduce the amount of water

used by your family.■ Describe how people use water.

Materialscalculator

Procedure1. Use the table on this page to calculate how

much water your family uses.

2. For three days, have the people who live inyour house keep a record of when they dothe activities listed in the table. If your fam-ily members forget to mark down theirwater usage, complete the activity usingyour own water-usage record.

3. The numbers in the table describe howmany liters an average person uses in a sin-gle day for the activity listed. Multiply thesenumbers by the number of people in yourhousehold who did these activities.

4. Add up the totals for each day. The final sumwill be the total amount of water used forthese activities in three days.

Conclude and Apply1. Collect Data How much water did your

family use in three days?

2. Study the activities listed in the table. Doyou see any ways to reduce the amount ofwater used?

3. Develop a detailed plan to reduce theamount of water your family uses.

Using Water

Share the results of this activity with yourclassmates. For more help, refer to the Science Skill Handbook.


Water Use

Activity Conditions Water Used

(L/person/day)

Washing dishes Water is running 113

by hand all the time

Washing dishes Sink is filled 19

by hand with water

Washing clothes Small load with 68

in machine high water setting

Washing clothes Full load with 45

in machine high water setting

Taking a shower 10 minutes long 150

Taking a bath Bathtub is full of 113

water

Flushing the Water-saving 23

toilet toilet

Brushing teeth Water is running 17

all the time

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SECTION 4 Land 305

Land as a ResourceHas your neighborhood changed lately? How about the out-

skirts of your town? Perhaps a grassy field has been turned into aparking lot or some nearby farmland has become a place wherenew homes were built. These changes, shown in Figure 18, areexamples of the different ways land is used as a resource. Howelse do people use land?

Land Use Think about where your food comes from. Land isused to raise the crops and animals humans use for food. A sim-ple peanut-butter-and-jelly sandwich requires land to grow thewheat needed to make bread, land to grow peanuts for thepeanut butter, and land to grow the sugarcane and fruit for thejelly. A hamburger? Land is needed to raise cattle and to growthe grain the cattle eat.

Think about your home, your school, and other places you go,like a park or a shopping mall. The things that you buy in theshopping mall come from factories. All these buildings take upspace. This means that every time a house, a mall, or a factory isbuilt, more land is used. Land is a renewable resource because itusually can be used over and over again. But one look at a globewill show you that the amount of usable land is limited. Therefore,wise choices need to be made when it comes to land use.

Land

■ Explain why land is a renewableresource.

■ Explain why trees are renew-able resources but many forestsare not.

■ Describe how mineral resourcesare used.

Resources are used to make some ofthe things you use every day.

Review Vocabularyhabitat: a place where an organ-ism lives that provides the thingsthe organism needs to survive

New Vocabulary

• conservation

• ore

Figure 18 This farmland soonwill be a new housing development.Infer What are some other waysthat land is used?

Standard—6.3.16: Explain that human activities, such as reducing the amount of forest cover, increasing theamount and variety of chemicals released into the atmosphere, and farming intensively, have changed thecapacity of the environment to support some life forms.

Also covers: 6.2.5, 6.2.6, 6.2.7, 6.5.7 (Detailed standards begin on page IN8.)

Kent Knudson/Stock Boston

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Using Land Wisely People need food, clothing,jobs, and a place to live, and each of these things takesspace. But preserving natural habitats, such as the oneshown in Figure 19, is also important. Recall that ahabitat is the place where organisms live. Ponds, wet-lands, and forests are examples of natural habitats. Ifa wetland is filled in to construct an apartment build-ing, an important natural habitat is lost.

Laws help control habitat loss and help people useland wisely. Before major construction can take placein a new area, the land must be studied to determinethe impact construction will have on the livingthings, the soil, and the water in the area. If endan-gered plants or animals live in the area, constructionmight not be allowed.

Problems also can arise when people use land forfarming or grazing animals. If these activities are notdone properly, soil can be eroded, causing its qualityto be reduced. Figure 20 shows how farmers andranchers work to reduce soil erosion problems.

Resources from LandPeople use land to grow crops, to raise animals, and to live on.

In addition to meeting human needs for food and shelter, landprovides two other important resources—forests and minerals.

Figure 19 People are workingto protect natural habitats in manyareas, such as this tropical rain for-est in Costa Rica.

Figure 20 Improper use ofrangeland can cause soil erosion.

Water belts help reduce water runoff and soil erosion byslowing the runoff and trapping soil.

(t)Lynn Stone, (bl)Lily Solmssen/Photo Researchers, (br)Larry Miller/Photo Researchers

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SECTION 4 Land 307

Forests Look around your class-room. Do you see books, paper, desks,and pencils? These products are madeof wood. Wood comes from trees in aforest that were cut down and takento a lumberyard to be processed intoboards and other wooden products.

In addition to providing much-needed wood, forests have an impor-tant effect on Earth’s atmosphere. Inthe process of photosynthesis, treesand other plants use carbon dioxide,water, and sunlight to produce oxy-gen and carbohydrates. As forestsgrow, they take in carbon dioxideand store carbon. If a forest is cutdown, it can no longer take in car-bon dioxide; therefore, more of thisgas is left in the atmosphere.Increases in atmospheric carbondioxide might cause global warming,which is a rise in temperaturesaround the world. Global warming could lead to changes inclimate that would impact natural habitats all over Earth.

Forest ConservationBecause forests are such a valuableresource, they must be used with care.

That’s why many states now have forest conservation laws.Conservation is the careful use of resources with the goal ofreducing damage to the environment. You can compare twomethods of harvesting forests Figure 21.

In select-cutting, shown in the top photo of Figure 21, a lim-ited number of trees are cut, and new trees are planted in theirplace. The young saplings grow among the older trees. By the timeall of the original trees are cut, a new forest has gradually grown.

In clear-cutting, shown in the bottom photo of Figure 21, allthe trees in a specific area are cut down and the cleared area isreplanted with new trees. One advantage of this method is thattrees in a specific area of a forest are of the same age and can beremoved more easily. But this method has drawbacks. Look againat the bottom photo of Figure 21. How do you think clear-cuttingaffected the plants and wildlife that lived in that area of the forest?

How do select-cutting and clear-cutting differ?

Figure 21 Forests are valuable resources that must be usedcarefully.

In select-cutting, certain trees in a forest are cut down and new trees are planted in their place.

Clear-cutting removes trees in aspecific area and the entire area isreplanted with new trees.

(t)J.P. Jackson/Photo Researchers, (b)Christiana Dittman from Rainbow

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Figure 22 Motorcycle parts andsaw blades are two of the manyproducts made from the ironextracted from the ore hematite.

Hematite

Renewable or Nonrenewable? If you’ve ever planted atree, you know that it takes time for a tree to grow. Some treestake many years to mature. However, trees can be viewed as arenewable resource because as one tree is cut, another can beplanted in its place.

Some forests, on the other hand, are nonrenewable. Why?Individual trees can be replanted, but forests are complexecosystems that support countless living things. These ecosys-tems can take a long time to develop. If many or all of the treesare removed from a forest, it could take centuries for the forestecosystem to develop again.

Mineral ResourcesTake a moment to look around the classroom again. List

three or four items that you use every day. Now try to decidewhat resources they were made from. It’s easy if the item is madeof wood. But what about the metal in your desk, in the doorhandle, or surrounding the windows? Metal objects come frommineral resources, which are found in rocks. So minerals areanother type of resource that is obtained from land.

No matter which type of rock you pick up, it’s likely made upof a number of minerals. Generally, it costs more to get thoseminerals out of the rock than the minerals are worth. But some-times large deposits of valuable minerals are found in one place.These minerals can be classified as ores. An ore is a mineralresource that can be mined at a profit. Figure 22 shows commonuses for iron ore.

What is an ore?

Indiana Academic

Standard Check

6.3.16: Explain that human activi-ties, … have changed the capacityof the environment to supportsome life forms.

What needs to be done?

(l)Geoff Butler, (c)Michael Simpson/Getty Images, (r)Ron Whitby/Getty Images

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SECTION 4 Land 309

Self Check1. Explain why Earth has only a limited amount of land,

yet land is a renewable resource.

2. Explain why trees are renewable resources, but someforests are not.

3. Compare and contrast minerals and ores.

4. Infer how using ores could contribute to an increase inair pollution.

5. Think Critically About 117,000 km2 of tropical rainforests are cut down each year. Why should peopleeverywhere be concerned about the loss of forestslocated in the tropics?

SummaryResources from Land

• Land provides food and shelter for humans.It also provides two other importantresources—forests and minerals.

• Forests play an important role in ouratmosphere.

Forest Conservation

• Conservation is the careful use of resourceswith the goal of reducing damage to theenvironment.

• Trees are renewable, some forests arenonrenewable.

Mineral Resources

• Valuable minerals found in large quantitiesare called ores.

• Ores are removed by mining, which can beharmful to the environment.

6. Use a Word Processor Compile a list of do’s anddon’ts for forest conservation.

7. Communicate Research one of the resources discussedin this section. Describe an environmental problemassociated with its use. Write a report that includespossible solutions to this problem.

Problems with Using Ores Ores, like fossil fuels, areresources found under Earth’s surface. To get to ores, largequantities of soil and rock often must be moved. This process iscalled mining. Mines can look unsightly, and the waste rockproduced by mines can pollute surface water. Air pollution alsois produced when large industrial plants process the ores, gen-erating dust and soot particles. Thus, the use of ores, like fossilfuels, affects the environment. Care must be taken to mine anduse the ores in ways that do not harm water resources, livingthings, and natural habitats.

Resource Use As you have learned, human activities havechanged the capacity of the environment to support some lifeforms. In addition, the way one resource is used often impactsanother. For instance, burning fossil fuels can cause air and waterpollution, as shown in Figure 23. Trees can be replanted to conservea forest, but the trees might die if they’re exposed to acid raincaused by burning fossil fuels. A farmer can manage a farm care-fully to lessen soil erosion, but if the water supply is polluted fromchemical runoff caused by mines, the crops will suffer regardless.Successful resource management is possible only if everyone usesresources wisely.


Figure 23 Industrial plants, suchas the one shown here in Ohio, cancreate air pollution when they burnfossil fuels to generate electricity orto manufacture products.

C. G. Randall/Getty Images

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Design Your OwnDesign Your Own

Imagine planning a small town. Your job in this lab is to draw up amaster plan to decide how 100 square units of land can be turned intoa town.

Real-World QuestionHow should land resources be used?

Form a HypothesisPeople need homes in which to live, places to work, and stores fromwhich to buy things. Children need to attend schools and have parksin which to play. How can all of these needs be met when planning asmall town?

Test Your HypothesisMake a Plan1. Make a square graph 10 blocks across and 10 blocks down. The

graph represents a 100-square-unit piece of land.

Goals■ Design a plan in which

100 square units ofland can be turned intoa small town.

Possible Materialsgrid paper (10 squares by

10 squares)colored pencils

Using Land

Parts of Your Town Number of Blocks Needed Office buildings 6 blocks in one group

Industrial plant 6 blocks in one group

School 1 block

Landfill for garbage 4 blocks in one group

Houses and apartments 44 blocks–can be broken up

Stores and businesses 19 blocks–can be broken up

Park 20 blocks–can be broken up

310 CHAPTER 10 Resources(l)Yann Arthus-Bertrand/CORBIS, (r)Steve McCutcheon/Visuals Unlimited

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2. The table on the previous page shows the different parts of a town that need tobe included in your plan. The office buildings and industrial plant are each 6blocks in size. These blocks must be treated as one group—they cannot bedivided. The landfill is 4 blocks in size. It, too, cannot be broken up.

3. All other town parts can be broken up as needed. Stores and businesses areareas in which shops are located, as well as medical offices, restaurants, andchurches.

4. As a group, discuss how the different parts of the town might be put together.Should the park be in the center of town or near the edge of town? Should theschool be near the offices or near the houses? Where should the landfill go?

5. How will you show the different town parts on your grid paper?

Follow Your Plan1. Make sure your teacher approves your plan before you start.

2. As a group, plan your town. Check over your plan to make sure that all townparts are accounted for.

Analyze Your Data1. Describe Where did you place the office buildings and the industrial plant?

Why were they placed there? Where did you place the houses, school, and busi-nesses? Explain why you placed each one as you did.

2. Evaluate Did you make one park or many parks? What are the advantages ofthe location(s) of your park(s)?

Conclude and Apply1. Where did you place the landfill? Will any of the townspeople be upset by its

location? To answer this question, it might help to know what direction thewind usually blows from in your town.

2. Where would you put an airport in this town? Keep in mind safetyissues, noise levels, and transportation needs.

LAB 311

Share the results of this lab with yourclassmates. For more help, refer to theScience Skill Handbook.

Mor

rison

Pho

togr

aphy

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A Walk in the Woods:Rediscovering America on the Appalachian Trail

by Bill Bryson

Bill Bryson writes of his attempt to walk the length—more than 3,381 km!—of the Appalachian Trail, andits climatic history.

Imagine it—a wall of ice nearly half a mile high,and beyond it for tens of thousands of square milesnothing but more ice, broken only by the peaks of avery few of the loftiest mountains. What a sight thatmust have been. And here is a thing that most of usfail to appreciate: we are still in an ice age, only nowwe experience it for just part of the year. Snow andice and cold are not really typical features of earth.Taking the long view, Antarctica is actually a jungle.(It’s just having a chilly spell.) At the very peak of thelast ice age 20,000 years ago, 30 percent of the earthwas under ice. Today 10 percent still is. . . .

No one knows much of anything about theearth’s many ice ages . . . One interesting theory given. . . is that the ice ages were caused not by falling tem-

peratures but bywarming ones.Warm weatherwould increaseprecipitation,which wouldincrease cloudcover, which wouldlead to less snowmelt at higherelevations. Youdon’t need a greatdeal of bad weatherto get an ice age.

Respond to the Reading1. When was the peak of the last ice age?

How much of Earth was covered by icethen?

2. What does the author speculate was thecause of the last ice age?

3. Linking Science and Writing Write atravel memoir about a nature walk ortrip you have taken. Use your knowledgeof science to explain some of the featuresyou saw.

The author reportson scientific research

concerning climatic changes that haveaffected the Appalachian Trail. During iceages, temperatures were much colder thanthey are now. The theory Bryson discussessays that to trigger these cold temperatures,the temperatures first had to warm up. Howdoes this theory about global warming differfrom some of the theories that are populartoday?

UnderstandingLiteratureTravel Writing Travel writing is one of theearliest forms of writing. Early travelerssuch as Marco Polo and ChristopherColumbus kept written records of theirexpeditions. Why is scientific researchimportant to travel writing in the form ofguidebooks and adventure tales?


GEORGIA

VIRGINIA

PENNSYLVANIA

NEW YORK

MAINE

VT.

N.H.

MASS.

CONN.

N.J.

R.I.

D.C.

MD.

DEL.

NORTH CAROLINA

SOUTHCAROLINA

OHIO

WESTVIRGINIA

Appalachian Trail

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Energy Resources

1. Fossil fuels such as coal, oil, and gas arenonrenewable energy resources.

2. Fossil fuels provide much-needed energy,but certain problems are associated withtheir use.

Alternative EnergyResources

1. Alternative energy resources, such as solarenergy, energy from the wind, hydroelectricpower, and geothermal energy, are constantand will not run out. They are consideredrenewable.

2. Though some of these resources do notcause pollution, certain drawbacks are asso-ciated with their use.

Water

1. Less than one percent of Earth’s total watersupply is available for people to use. Peopleuse water to meet their basic needs and inindustry and agriculture.

2. Clean water can become a nonrenewableresource if water supplies are overusedor polluted.

Land

1. Land is a valuable resource used for food,shelter, and other needs. Wood and miner-als are two other important resources thatcome from land.

2. All of Earth’s resources must be managedwisely. If one resource is polluted or over-used, other resources can be affected as well.

CHAPTER STUDY GUIDE 313in6.msscience.com/interactive_tutor

Copy and complete the following concept map on resources.

ResourcesRenewable

landenergy energy water land

can becan be

Solar Wind Fossil fuels

Some forestsHydroelectric

(l)Jim McDonald/CORBIS, (r)Jeremy Hardie/Getty Images

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http://in6.msscience.com/interactive_tutor

Fill in the blank with the correct vocabularyword or words.

1. is energy that comes fromthe Sun.

2. Careful use of resources with the goal ofreducing damage to the environment iscalled .

3. forms from the remains of deadplants and animals.

4. Water that soaks into the ground and col-lects in the small spaces between bits ofrock and soil is called .

5. Harmful waste products, chemicals, andsubstances found in the environment arecalled .

6. When pollution can be traced directlyto its point of origin, it is referred to as

.

Choose the word or phrase that best answers thequestion.

7. What does nuclear energy produce?A) solar energy C) radioactive wasteB) conservation D) acid rain

8. What is water in rivers, streams, lakes, andreservoirs called? A) peat C) groundwaterB) surface water D) natural gas

9. Which of the following is an example of afossil fuel?A) wind C) natural gasB) water D) uranium

10. Approximately what percentage of theenergy used in the United States isfrom coal?A) 12 C) 32B) 23 D) 52

11. What kind of mineral resource can bemined for a profit?A) solar cell C) damB) wind D) ore

12. What kind of energy is generated by largedams built on rivers?A) wind C) hydroelectricB) nuclear D) solar

13. When many windmills are located in oneplace in order to generate electricity, whatdo they form?A) wind farm C) oil wellB) dam D) nuclear reactor

14. What is the source of energy used bygeothermal power plants? A) water C) heated rocksB) atoms D) wind

15. When gases released by burning coal or oilmix with water that is in the air, what canthey form?A) acid rain C) conservationB) fission D) groundwater

16. A nonrenewable resource can’t be replacedin less than about how many years?A) 5 C) 50B) 10 D) 100

17. What process describes splitting the nucleiof certain elements?A) filtration C) runoffB) fission D) hydroelectricity

314 CHAPTER REVIEW

acid rain p. 288conservation p. 307fossil fuel p. 286geothermal energy p. 296groundwater p. 300hydroelectric power p. 295nonpoint source

pollution p. 301

nonrenewable p. 290nuclear energy p. 297ore p. 308point source

pollution p. 301pollution p. 288renewable p. 291solar energy p. 291

in6.msscience.com/vocabulary_puzzlemaker

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http://in6.msscience.com/vocabulary_puzzlemaker

CHAPTER REVIEW 315in6.msscience.com/chapter_review

18. Explain With all of the paper products thatpeople use every day, why doesn’t Earthrun out of trees?

19. Infer Some heavily populated countriescause less environmental damage thancountries with far fewer people. Why?

20. Infer A shark that lives at sea is founddead. It has chemicals in its body that canbe traced to pesticides used on farms.How can this happen?

21. Draw Conclusions Why shouldn’t nuclearwastes be stored near an area prone toearthquakes?

22. Infer Once a mineral resource is classifiedas an ore, will it always remain an ore?Explain your answer.

23. Predict If a well were drilled into a rocklayer that contains oil, natural gas, andwater, which substance would be encoun-tered first? Explain.

Use the figure below to answer question 24.

24. Interpret Scientific Illustrations The figurebelow shows a water-purification plant. Inyour own words, describe the path watertakes from a stream to your faucet.

25. Communicate Make an outline that explainshow nuclear energy is used to produceelectricity.

26. Make and Use Tables Make a table showingthe different ways water can be used as aresource.

27. Design a Poster Research water sources and how they are used in your area. Makea poster that shows your results. Displaythis poster for your class.

28. Write a Poem Write a poem about land as a resource. Include reasons why land isimportant and the different ways land canbe used as a resource.

Storage tanksto consumer

Pumping station

Use the graph below to answer questions 29 and 30.

29. Calculate What percentage of the electricity inthe United States is generated by nonrenew-able resources?

30. Calculate A small town may use 250,000 kW ofenergy per day. How many kw of energy is fromhydroelectric power?

Other0.3%

Sources of Electricity in the U.S.

Hydroelectric10.7%

Natural gas8.5%

Coal56.4%

Nuclear21.9%

Petroleum2.2%

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The assessed Indiana standard

appears above the question.

Record your answers on the answer sheetprovided by your teacher or on a sheet of paper.

1. The circle graph below shows the use of nat-ural gas in the United States during 2002.

Which uses the most natural gas?

A commercial

B electric power

C industrial

D residential

2. Why are coal, petroleum, and natural gasdefined as fossil fuels?

A They are burned to release energy.

B They are nonrenewable and will run out.

C They cause air pollution when burned.

D They were formed from remains ofancient life.

3. Which is the main source of energy forhomes and factories in the United States?

A fossil fuels

B geothermal

C hydroelectric power

D solar power

The photo below shows a geyser, formed whengroundwater is heated by hot rocks or magma.

4. Which energy source is shown?

A fossil fuels

B geothermal

C hydroelectric

D solar

5. What is a disadvantage of using theresource shown above?

A Deep wells must be dug.

B Land can flood and disturb wildlife.

C Mining can pollute surface water.

D Waste contains cancer-causing materials.

Other0.1%

Commerical14.9%

ElectricPower26.6%

Industrial34.8%

Residential23.6%

Natural Gas Use in theUnited States (2002)

316 INDIANA

IndianaIndianachapter chapter

6.3.17

6.3.17

6.3.17

6.3.17

6.3.16

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ISTEP+ PRACTICE 317

6. Which energy source uses heat frommagma or hot dry rocks?

A geothermal

B hydroelectric

C nuclear

D wind

The illustration below shows how oil and nat-ural gas collect in rock layers.

7. Where does oil collect in rock layers?

A above natural gas and impermeablerock, below water

B above natural gas, below water andimpermeable rock

C above water and natural gas, belowimpermeable rock

D above water, below impermeable rockand natural gas

The circle graph below shows energy use inthe United States.

8. Renewable energy made up 6 percent ofthe total U.S. energy consumption. Whatpercent of the renewable energy consump-tion was provided by hydroelectric energy?

9. Inferring from the graph above, why doyou think that hydroelectric energy wasused more than solar, geothermal, and windsources? What are some disadvantages ofusing hydroelectric energy?

10. Explain how the use of fossil fuels byhumans affects the weather and atmos-phere. What could humans do to avoidthese problems?

Energy Use in the United States, 2002

Nuclear8.3%

Oil39.4%

Coal22.7%

Natural gas23.6%

Hydroelectric2.7%

Biomass2.8%

Geothermal, wind,solar, and other

0.5%

ISTEP+ PracticeISTEP+ Practice

Don’t Rush Stay focused during the test and don’t rush, evenif you notice that other students are finishing the test early.

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6.3.176.3.8

6.3.13

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Water inpermeable rock

Natural gas Oil

Natural gas

Oil

Impermeable rock

Oil

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