Description
Please read and bid only if you understand the attached documents.
final.docx <--Assignment
chpt.9.pdf <--Reading
3 attachmentsSlide 1 of 3attachment_1attachment_1attachment_2attachment_2attachment_3attachment_3
Unformatted Attachment Preview
Read below, I’ve added the PDF of the reading required for
the assignment as a second file.
Cite any outside sources, spell checked and edited, plagiarism
checked, use the attached PDF as your primary source and
post it to the Assignments Link for grading.
Open Book Final Exam: Based on the textbook readings,
Chapters 9 required this week, please respond in 300 - 400
words (excluding the reference section). Try to bring in the
course material you have learned to inform your response.
Please create an academic, researched, critically thought out
response similar to a Discussion Question response.
1. What is a resource? How do political-cultural,
technologic, and economic factors determine whether
substances in the environment become valuable
resources? (Chapter 9)
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
Earth’s Resources and Environmental Protection
Salt flats in Salar de Uyuni, Bolivia. These deposits are the world’s richest known source of lithium.
JJBPhoto / Alamy
A Look Ahead
What Is a Natural Resource?
A natural resource is something created by natural processes that is useful to people. Usefulness is determined by a mix of cultural,
technological, and economic factors in addition to the properties of a given resource. We often substitute one resource for another as our needs
change.
Geologic and Energy Resources
Geologic resources include metals and nonmetals. As geologic resources are depleted, they are usually replaced with substitute materials.
Landfills accumulate used materials and may one day be a source of materials for reuse. Our principal energy resources come from three fossil
fuels—oil, coal, and natural gas. As fossil fuels are depleted, they are likely to be replaced with nuclear and renewable energy.
Air and Water Resources
Pollution results when a substance is discharged into the air or water faster than it can be dispersed or removed by natural processes. Pollution
prevention and recycling are growing in importance as methods for solving pollution problems.
Forests
Forests are an essential and renewable resource for diverse purposes, including fuel, fiber, recreation, biodiversity, and carbon storage. In some
cases, these uses of forests are compatible, but in many they are not, and decisions about forest use are increasingly difficult as remaining
resources dwindle.
Salar de Uyuni, a vast salt flat in Bolivia, is home to the world’s richest untapped deposits of lithium. Interest in, and demand for, this relatively lightweight
metal has risen dramatically with the development of lithium ion batteries, which are used in a wide range of electronic devices, including cell phones and
laptop computers. Interest is especially high because lithium ion batteries are the best technology at present for powering electric and hybrid vehicles.
Bolivia, with about half the world’s lithium resource, is looking to perhaps dominate or even control world lithium markets. The current president, Evo Morales,
has asserted Bolivian control over natural resources by nationalizing natural gas and some mining companies, antagonizing foreign investors. Many imagine
the lithium deposits forming a major export market that can boost the Bolivian economy, but there is always a risk that at some point, some other technology
is likely to replace lithium as a power storage medium, and at that point, world demand for this metal will probably drop. In addition, high lithium prices have
stimulated searches for resources elsewhere and substantial lithium resources were recently discovered in Afghanistan. Wealth generated from exploiting
such deposits may be great, but is likely fleeting.
Everything we consume is extracted from our planet and returned to it in one form or another. As we use Earth’s resources of air, water, minerals, energy,
plants, and animals, we simultaneously discharge our waste into the environment. As Earth’s human population of 6.8 billion approaches 9 to10 billion, likely
late in the twenty-first century, consumption of resources will increase. This expanded population will place tremendous stress on Earth’s remaining
1 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
resources and the ability of the planet’s air, water, and land to accommodate human waste.
Consumption and waste vary among cultures and over time. Different cultures at different times have obtained energy from wood, coal, petroleum, natural
gas, running water, nuclear energy, the wind, and the Sun. Issues of natural resource use and environmental quality must be understood in both their
physical and human dimensions.
Resource management is exceedingly complex, because each resource varies geographically and physically. Resources also vary in value, depending on
human factors: culture, technology, beliefs, politics, economics, and government style. Many resources are publicly controlled, so resource management is a
political process.
The issue of lithium in Bolivia illustrates this complexity. Bolivia is a very poor country, and its economy is heavily dependent on natural resources.
Struggles over resource issues have dominated Bolivian politics in recent years, especially issues of ownership and control of water and fossil fuels.
Development of lithium offers an opportunity to generate income but also carries the risk of tying economic development to a very specialized technology,
and world demand for lithium is both highly uncertain and beyond Bolivia’s control. Similarly, development of mineral resources in Afghanistan would offer the
opportunity of significant foreign exchange earnings, but would come at the risk of economic dependency on a limited number of resources and customers,
and might not generate comparable income for farmers as they have historically earned from producing opium.
In this chapter, we explore the factors that affect the value of resources. These factors include the physical characteristics of resources and the natural
systems in which they exist, the changing technology of resource use, and human value systems. We then consider how changing resource values affect
what and how much of our resources we use. Finally, we look at environmental pollution and resource conflict and management.
What Is a Natural Resource?
A natural resource is anything created through natural processes that people use and value. Examples include plants, animals, coal, water, air, land,
metals, sunlight, and wilderness. Natural resources are especially important to geographers, because they are the specific elements of the atmosphere,
biosphere, hydrosphere, and lithosphere with which people interact. Natural resources can be distinguished from human-made resources, which are human
creations or inventions such as money, factories, computers, information, and labor.
We often use natural resources without considering the broader consequences of doing so. For example, burning oil to generate heat or to power an
automobile engine pollutes the atmosphere with exhaust gases. The nitrogen oxides emitted into the atmosphere contribute to acid rain, which then pollutes
streams. Oil consumption also weighs heavily on international economic and political relations.
Characteristics of Resources
A substance is merely part of nature until a society has a use for it. Consequently, a natural resource is defined by the three elements of society:
A society’s cultural values influence people’s decision that a commodity is desirable and acceptable to use.
A society’s level of technology must be high enough to use the resource.
A society’s economic system affects whether a resource is affordable and accessible.
Consider petroleum as an example of a natural resource in North America:
Cultural values. North Americans want to drive private automobiles rather than use public transport such as trains.
Technology. Petroleum is the preferred fuel in private automobiles because autos are easily powered by gasoline engines.
Economic system. North Americans are willing to pay high enough prices for gasoline to justify removing petroleum from beneath the seafloor and
importing it from distant places (Figure 9-1).
Figure 9-1 Net oil imports and exports.
2 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
The largest oil importers are the wealthy nations of North America and Europe. Many developing nations are also net importers, and although
the quantities they import are much smaller, the cost may be a higher percentage of the total national income for poor countries.
Data from U.S. Energy Information Administration
The same elements of society apply to the study of any example of a natural resource: rice to the Japanese, diamonds to South Africans, forests to
Brazilians, and clean air to residents of Los Angeles. In every case, a combination of the three factors is necessary for a substance to be valued as a natural
resource. Differences among societies in cultural values, the level of technology, and economic systems help geographers understand why a resource may
be valuable in one place and ignored elsewhere.
Cultural values and natural resources
To survive, humans need shelter, food, and clothing, and make use of a variety of resources to meet these needs. We can build homes of grass, wood, mud,
stone, or brick. We can eat the flesh of fish, cattle, pigs, fish, or mice—or we can consume grains, fruit, and vegetables. We can make clothing from animal
skins, cotton, silk, or polyester. Cultural values guide a process of identifying substances as resources to sustain life.
A swamp is a good example of how shifting cultural values can turn an unused feature into a resource. A century ago, swamps were seen in the United
States as noxious, humid, buggy places where diseases thrived instead of a place that provides usable commodities. Swamps were valued only as places to
dump waste or to convert into agricultural land. Eliminating swamps was good, because it removed the breeding ground for mosquitoes while simultaneously
creating productive and valuable land.
During the twentieth century, cultural values changed in the United States. Scientists and environmentalists praised the value of swamps and documented
their importance in controlling floods, providing habitat for wildlife, and reducing water pollution. Philosophers increasingly regarded nature as beautiful and
praiseworthy. Changing public attitudes toward swamps is reflected in our vocabulary: instead of calling them swamps, now we use a more positive term,
wetlands.
As a consequence of cultural change, wetlands now are a valued land resource, protected by law (Figure 9-2). We restore damaged wetlands, create new
ones, and restrict activities that might harm them. Even in the Netherlands, where deep-rooted cultural and landscape traditions are based on draining
wetlands to convert them into farmland, some of these same farmlands are now being converted back to wetlands to improve water quality and enhance
species diversity.
Figure 9-2 Wetlands in southern Louisiana.
Louisiana is losing wetlands at a rate of about 75 square kilometers (29 square miles) per year. In addition to providing important water quality and
ecological functions, these wetlands help protect cities such as New Orleans from flooding.
© Comstock/Corbis
Technology and natural resources
The utility of a natural substance depends on the technological ability of a society to obtain it and to adapt it to that society’s purposes. Metals are elements
that can be formed into materials that have high strength in relation to their weight, can generally withstand high temperatures, and are good conductors of
heat and electricity. A metal ore is not a resource if the society lacks knowledge of how to recover its metal content and how to shape the metal into a useful
object, such as a tool, structural beam, coin, or automobile fender.
Earth has many substances that we do not use today, because we lack the means to extract them or the knowledge of how to use them. Things that might
become resources in the near future are potential resources. As a result of their high level of biodiversity, tropical rain forests are brimming with plants and
animals that North Americans regard as potential resources. New medicines, pesticides, and foods might be developed from these substances. To the
indigenous peoples of the Amazon rain forest, some of these plants and animals are already resources. But deforestation threatens the availability of these
resources for indigenous peoples and their potential use by others even while it creates economic opportunities for Brazilians. By destroying the rain forest,
we are diminishing Earth’s pool of both current and potential resources.
Human needs can drive technological advances. People living in cold climates invented insulated homes and heating technology. The need to increase the
supply of food drove people to develop new agricultural technology.
Because human need drives many technological advances, new technologies may emerge when a resource becomes scarce. New technology for reusing
materials is being developed in part because space in landfills has become a scarce resource, especially in large urban areas of relatively developed wealthy
countries, where consumption is highest. This space scarcity is stimulating development of new methods for reusing and recycling materials. Most waste
currently is not reusable. But as we deplete the resource of landfill space, we will make more things recyclable and manufacture new products from waste,
and waste materials themselves will become resources.
3 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
Economics and natural resources
Natural resources acquire a monetary value through exchange in a marketplace. The price of a substance in the marketplace, as well as the quantity that is
bought and sold, is determined by supply and demand. Common sense tells us some principles of supply and demand:
A commodity that requires less labor, machinery, and raw material to produce (for example, a bicycle) will sell for less than a commodity that is harder to
produce (for example, an automobile).
The greater the supply, the lower the price (for example, corn). The greater the demand, the higher the price (for example, Superbowl tickets).
Consumers will pay more for a commodity if they strongly desire it (for example, a computer) than if they have only a moderate desire (for example, a
textbook).
If a product’s price is low (for example, beer and hamburgers), consumers will demand more than if the cost is high (for example, champagne and prime
rib).
In general, natural resources are produced, allocated, and consumed according to rules of supply and demand. Water is a good example. In areas where
water is plentiful because of high rainfall and low demand—such as northern Minnesota—consumers pay a low price, little more than the cost of pumping it
from the nearest well, river, or lake. But in the arid southwestern United States, water rights must be purchased, and scarce water must be carried hundreds
of kilometers through pipelines and aqueducts. Thus, prices are generally higher. Because of these high costs, the government may subsidize water
provision, and prices paid by consumers may not reflect the true cost of obtaining the resource.
Many important natural resource problems result from the inability of markets to account for pollution. Externalities are spill-over effects arising from
production and/or consumption of goods and services for which appropriate compensation is not paid. They are external to the marketplace. The people who
buy the electricity pay for the electricity directly. The price they pay reflects their desire to have the electricity and their willingness to pay for it. But people
downwind from the power plant receive the pollution, whether they like it or not. The power plant does not directly pay for the privilege of discharging pollution
to the atmosphere, although it does bear some of the costs of pollution control. This un-priced pollution thus constitutes an externality—a hidden cost. If the
power plant were charged for its pollution and the people who receive it were compensated, perhaps the power plant would emit less pollution and thereby
have less impact on the people exposed to it.
Example: Uranium
In every society, level of technology, economic system, and cultural values interact to determine which elements of the physical environment are resources
and which are not. Uranium is a good example. Until the 1930s, uranium was a resource only because its salts made a pretty yellow glaze for pottery. After
German physicists realized that the great energy stored in uranium atoms might be released by “splitting” their nuclei (nuclear fission), uranium gained value
as weaponry during World War II:
Technology. The United States and its allies, fearing that Germany might develop a nuclear bomb, began what was known as the Manhattan Project, a
crash program to develop the bomb technology first. Germany surrendered before the Manhattan Project achieved its goal, but the technology was
eventually developed and used to win the war against Japan.
Economic system. After World War II, nuclear technology was applied to generating electrical power. Nuclear-generated electricity was slow to gain
acceptance because it was more expensive than alternative power sources, but after Middle East petroleum supplies were threatened during the 1970s,
more nuclear power plants were built. The cost of nuclear power has had little to do with the cost of uranium, which is cheap and abundant. Recent
increases in the price of non-nuclear-generated electricity associated with growing demand, concern about global warming, and rising prices of fossil
fuels have renewed interest in nuclear power.
Cultural values. With the construction of nuclear power plants, the public became increasingly concerned about the risks. Following power-plant
accidents at Three Mile Island in Pennsylvania (1979) and Chernobyl in Ukraine (1986), government agencies regulated nuclear plant safety much more
closely. Higher safety standards increased the cost of nuclear power at a time when conservation efforts had succeeded in reducing demand for
electricity. Fear of the hazards of nuclear power has prevented growth of the industry, even though the hazards are probably less than those routinely
accepted in other aspects of everyday life, such as the risk of death in an automobile or airplane accident. Orders for new power plants ceased in the
United States during the 1980s. Renewed concern about security of radioactive materials may also reduce support for nuclear power.
Substitutability
Many natural resources are valued for specific properties—coal for the heat it releases when burned, wood for its strength and beauty as a building material,
fish as a source of protein, clean water for its healthiness. In most cases, several substances may serve the same purpose, so if one is scarce or expensive,
another can be substituted (Figure 9-3). Copper is an excellent conductor of electricity, but it may be expensive relative to wire made of other metals that can
be substituted. For information transmission, such as in computer networks, using light in a fiberoptic cable is more efficient than using electrons in a copper
wire.
Figure 9-3 House construction in the United States.
4 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
Wood is used in house construction in the United States mostly because it is relatively inexpensive and easy to work with. Here, oriented strand board,
a manufactured wood product, is being used in exterior walls in new construction. This board is much cheaper than sawn lumber but has ample
strength for covering exterior walls, floors, and roofs. The cost of this wood product is competitive with that of foam board made from petroleum that is
an alternative to wood-based board.
Montej/iStockphoto
The substitutability of one substance for another is important in stabilizing resource prices and limiting problems caused by resource scarcity. If one
commodity becomes scarce and expensive, cheaper alternatives usually are found. Such substitution is central to our ability to use resources over extended
periods without exhausting them and without decline in our standard of living.
However, many resources have no substitutes. There is only one Old Faithful Geyser and only one species of sperm whale, so if we destroy Old Faithful or
force extinction of the sperm whale, we have no substitutes waiting to be tapped. Other geysers and whales exist, but they are not the same as those we
now know. The uniqueness of these resources is the essence of their value.
Renewable and Nonrenewable Resources
In thinking about Earth’s resources, we distinguish between those that are renewable and those that are not:
Nonrenewable resources form so slowly that for practical purposes, they cannot be replaced when used. Examples include coal, oil, gas, and ores of
uranium, aluminum, lead, copper, and iron.
Renewable resources are replaced continually, at least within a human life span. Examples include solar energy, air, wind, water, trees, grain,
livestock, and medicines made from plants.
Even a renewable resource can be depleted, or used to a point at which it can no longer be economically used. The only ones we cannot deplete are solar
energy and its derivatives: wind and precipitation.
Geologic and Energy Resources
Geologic resources are substances that we derive from the lithosphere. They are basic materials that we use to construct roads and buildings, manufacture
goods, and power transportation. They include rocks and minerals such as limestone and metal ores, as well as fossil fuels. Without these resources,
modern industrial societies could not function. Our use of geologic resources in industry and commerce is governed primarily by technology and economics.
We value most minerals for their properties of strength, malleability (ability to be shaped), weight, and chemical reactivity rather than for their aesthetic
characteristics. Few car owners care if the engine is made from aluminum or iron; what matters is that it is powerful, durable, and efficient. Few people care
very much whether the roof of their house is made from slate or asphalt shingles, as long as the roof keeps out the rain and doesn’t cost too much. Gold is
the rare exception of a mineral valued mostly for its beauty (more than three-quarters of gold use is in jewelry), although even gold is increasingly demanded
for industrial uses, especially electronics.
Because we value a mineral primarily for its mechanical or chemical properties, our use of mineral resources is continually changing as our technology and
economy change. As new technological processes and products are invented, demand can suddenly increase for materials that had little use in the past.
When these new processes and products replace older ones, demand for minerals that were previously important may be reduced. As a result of changes in
consumer demand, remaining supplies, and prices, one mineral may become more favored while another is less desired.
Mineral Resources
The terms Stone Age, Iron Age, and Bronze Age indicate the importance of particular minerals at various times in the past. Minerals are as essential to
civilization as plant, animal, water, and energy resources. They are present in virtually every product we manufacture, and though their value may be a small
part of the total value of a finished good, those products could not be made without minerals (Figure 9-4).
Figure 9-4 Annual per capita consumption of nonenergy minerals in the United States, 2007.
5 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
U.S. Census Bureau
Earth has 92 naturally occurring chemical elements, but most of Earth’s crust is made up of eight elements: oxygen, silicon, aluminum, iron, calcium,
sodium, magnesium, and potassium. These elements, as well as rarer ones, combine to form thousands of minerals, each with its own properties and
distribution pattern throughout the world. Each mineral is potentially a resource if people find a use for it.
Metallic minerals, such as copper, lead, silicon, tin, aluminum, and iron, usually occur in ores, from which they must be extracted. Nonmetallic minerals,
including building stone, graphite, rubies, sulfur, slate, and quartz, are generally easier to obtain because they are more plentiful and usually require less
processing. Both metallic and nonmetallic minerals must be discovered, mined, transported, refined, and manufactured into useful goods.
Variations in Mineral Use
Historically, the use of particular metals and nonmetals has fluctuated between periods of high demand and price and periods of low demand and price.
Discovery of a new resource could create a “rush” of people to the area of discovery. The “gold rushes” to California, Colorado, and Alaska are nineteenthcentury examples. The period between 1970 and 1985 featured especially volatile mineral prices, as a result of rises and declines of industrial output and
inflation. For instance, the price of copper doubled between 1973 and 1980, and then it fell nearly 40 percent between 1980 and 1985. Prices of most
minerals were relatively stable through the 1990s, but since 2003, prices of some metals have risen dramatically in response to growing industrial production
in China and India. For example, the price of copper tripled between 2003 and 2006, and between 2005 and 2008, the price of steel doubled. The prices of
these commodities plunged in 2008, dropping to their 2004-05 levels in just a few months. Prices remained low in 2009 and 2010 because of the global
economic recession. Historically, such spikes in mineral commodity prices have been short-lived, but sustained industrial growth in China, India, and
elsewhere may prolong these price trends.
Mineral deposits are not uniformly distributed around the world. Most of the world’s supply of particular minerals is concentrated in a handful of countries.
For example, although aluminum is one of the most abundant elements on Earth, in 2009, just six countries—Australia, Brazil, China, Guinea, India, and
Jamaica—produced about 87% of the world’s total aluminum ore (bauxite) (Figure 9-5). Large countries such as the United States, Russia, Canada, China,
and Australia are especially rich in metal and nonmetal mineral resources.
Figure 9-5 Share of production for the major producers of four common minerals: bauxite, nickel, zinc, and copper, 2009.
6 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
Data from the U.S. Geological Survey
The concentration of mineral resources and production in a few countries favors the establishment of cartels. A cartel is a group of countries or firms that
agree to control a particular market by limiting production in order to drive up prices. During the 1970s, when world demand for minerals was strong, a few
cartels were able to control world markets for brief periods. But weak demand, falling prices, and political instability have limited the strength of cartels in
recent years. In addition, the United States—the largest consumer of most minerals—has accumulated a stockpile of important minerals to protect against
short-term reductions in supply caused by high prices, political instability, or hostile foreign governments.
Depletion and Substitution
Fluctuations in the price of a mineral as a result of actions by a cartel, a political dispute, or a limited supply rarely continue for a long period of time. If high
prices persist for several decades, technological innovations usually enable the substitution of cheaper minerals for more expensive ones. When the price of
copper rose rapidly in the 1970s, for instance, plumbers began to substitute polyvinyl chloride (PVC). Today, PVC (a plastic made from petrochemicals) has
largely replaced copper pipe for plumbing in new buildings. The likelihood that substitute products will be developed adds great risk to enterprises of
countries that become dependent on the production and sale of specific mineral commodities.
The substitution of one mineral for another has an important consequence: Even though world supply of a mineral resource may be limited, we will never
run out of it. The reason is that if the supply of a resource dwindles relative to demand, its price will rise. The increase in price has four important
consequences:
1. Demand for the mineral will decrease, slowing its rate of depletion.
2. Mining companies will have added incentive to locate and extract new deposits of the mineral, especially deposits that might have been neglected when
prices were lower.
3. Recycling of the mineral will become more feasible.
4. Research to find substitute materials will intensify, and as use of the substitute increases, demand for the scarce mineral will cease before the supply is
exhausted.
Although at current rates of use, the world would exhaust its remaining supply of lead in 23 years, zinc in 20 years, and copper in 33 years, there should
not be any fear that these minerals will be depleted within your lifetime. However, if you know that a company has just invented a product that will replace
one of these minerals inexpensively, this would be a sound investment!
Disposal and Recycling of Solid Waste
The average American throws away 2.1 kilograms (4.6 pounds) of solid waste per day, twice as much as people did in 1960. Paper accounts for one-third of
all solid waste in the United States. Discarded food and yard waste accounts for another one-third (Figure 9-6). Relatively developed societies generate large
quantities of packaging and containers made of paper, plastic, glass, and metal. We dispose of this solid waste in three ways: landfills, incineration, and
recycling. Each of these methods poses significant problems, either in environmental degradation or in costs of disposal. Normally the choice of one disposal
method over another means that costs are shifted from one group to another, making conflict inevitable.
Figure 9-6 Composition and disposition of U.S. solid waste, 2006.
7 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
Paper and paperboard form the largest part of solid waste generated in the United States. About one-half of all paper and paperboard waste is
recovered and reused; much of this is made into cardboard boxes used for shipping. Recovery rates for aluminum are about one-third.
U.S. Census Bureau
Landfill disposal
About 55 percent of solid waste generated in the United States is trucked to landfills and buried under earth in sanitary landfills in which a layer of earth is
bulldozed over the garbage each day. They are considered sanitary because burying the garbage reduces emissions of gases and odors from the decaying
trash, prevents fires, and discourages vermin. Unlike air and water pollution, which are reduced by dispersal into the atmosphere and rivers, solid-waste
pollution is minimized by concentrating the waste in thousands of landfills. However, landfills have been closed in many communities because they might
contaminate groundwater, devalue property, or have been filled to capacity. Opening new landfills is difficult because present environmental regulations are
more stringent, and local opposition to new landfills is usually overwhelming. The result in many areas has been a solid-waste crisis. Disposal sites are few
and costly and some communities must pay to use landfills elsewhere. San Francisco trucks solid waste to Altamont, California, 100 kilometers (60 miles)
away. Passaic County, New Jersey, hauls waste 400 kilometers (250 miles) west, to Johnstown, Pennsylvania.
Incineration
One alternative to burying waste in landfills is incinerating it. Incineration reduces the bulk of trash by about three-fourths, and the remaining ash requires far
less landfill space. Incineration also provides energy. The incinerator’s heat boils water, producing steam that can be used to heat homes or to generate
electricity by operating a turbine. More than 100 incinerators now burn and recover energy from about 12 percent of the trash generated in the United States.
However, because solid waste is a mixture of many materials, it does not burn efficiently. Burning releases some toxic substances into the air, while some
remain in the ash.
Recycling
Recycling solid waste reduces the need for landfills and incinerators and reuses natural resources that already have been extracted. Recycling
simultaneously addresses both pollution and resource depletion. Most U.S. communities have instituted some form of mandatory or voluntary recycling, and
about 32 percent of municipal solid waste in the United States is recycled.
Several barriers to recycling must be surmounted:
Waste separation. Solid waste comprises a variety of materials that must be separated to recycle (Figure 9-7). Metals containing iron can be pulled out
of the pile magnetically; but paper, yard waste, food waste, plastics, and glass cannot be separated easily from each other. Consequently, many
communities require consumers to separate solid waste themselves. Typically, consumers must place newspaper, glass, plastic, and aluminum in
separate containers for pickup. Each type is collected on a different day or by a different truck, and is shipped to a specialized processor. The procedure
is generally more expensive for the community than picking up all the trash together.
Figure 9-7 Resource recovery.
Resource recovery from solid waste requires sorting and separating different types of materials. One approach is to collect them together and
separate them at a centralized facility like this one. Alternatively they can be separated at the source (home, school, work) and transported
separately to reprocessing facilities.
8 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
AP Photo/Mike Derer
Consumer resistance. Separation for recycling is a nuisance for people in relatively rich developed countries who are used to throwing things away. To
encourage recycling, some communities charge high fees to pick up nonrecyclables but take recyclables at little or no charge. Bottle and can laws
requiring a deposit on beverage containers have been enacted in many states to encourage recycling and reduce roadside litter.
Lack of market. To succeed, recycled products must have a market. The lack of an assured market for many recycled products is perhaps the most
difficult obstacle to increased recycling. Demand for recycled goods among industries and consumers is uncertain. For example, mixed plastics can be
used as a substitute for wood in products such as picnic tables and playground equipment. The price of wood is not very different from that of recycled
plastic; however, for aesthetic reasons, most consumers prefer wood. This preference helps keep the market for recycled plastic small. To increase
consumer acceptance, the quality of recycled material must also improve. Poor quality has resulted from the fact that recycling became mandatory
before proper manufacturing methods had been developed.
Hidden costs. Recycling involves far more than just “melting down and reshaping.” For example, to recycle paper, ink must be removed, which is an
additional step compared to conventional papermaking and therefore an added cost. It is difficult to remove all of the ink, so recycled paper is
unacceptable for some uses because it is too gray or speckled. Removing ink may create some pollution, though probably less than would be produced
in making virgin paper. The relatively high cost of processing and the lower value of the products results in a limited market for the recycled materials.
Indirect losses. Trash burns only if it contains enough combustibles. If paper is recycled and yard waste is composted instead of being thrown in the
trash, the trash may be difficult to burn. As recycling has increased, some communities have not had enough combustible waste to operate their
incinerators.
Many companies are developing manufacturing methods and packaging that facilitate recycling. To reduce packaging volume, detergent is being sold in
concentrated form, refillable containers are available for more products, and toner cartridges for some photocopy machines are built for reuse rather than for
disposal. At the same time, however, the low cost of many materials means that recycling depends on cheap labor to separate materials prior to reuse.
Opportunities for recycling are growing, particularly as systems are developed to make it easier for consumers to recycle waste and for industry to recover
recycled materials. The concentration of gold in computers, on a weight basis, is significantly greater than in gold ore. If sufficient quantities of old computers
are brought together in one place, it becomes profitable to extract that gold from the computers.
One alternative is to require consumers to bear a greater share of the cost of waste generation. If those costs are clearly associated with the products that
generate the wastes, then consumers have an incentive to reduce waste. For example, in 2002, the Irish government imposed a tax of about 17 cents on the
use of disposable plastic shopping bags. Within a year, use of such bags dropped 95 percent, as consumers either reused bags or carried their purchases in
other, reusable containers. The portion of plastic bags in litter dropped from 5 percent to 0.3 percent.
Landfills: An example of changing resource values
Garbage dumps are nothing new, as excavations of ancient cities reveal, but they are growing much more rapidly than in the past. Traditionally, food waste
was fed to livestock, iron was used in durable goods, packaging was simple, and plastic products were unknown. Far fewer goods were manufactured. Our
“throwaway culture” is a modern invention.
Garbage dumps have been sited in swamps and on other low-value land. For years, garbage simply was dumped and left uncovered. Rubber tires,
deliberately burned in landfills to keep fires going, emitted offensive black smoke. Fires smoldered, rats thrived, flies buzzed, and homes situated downwind
rarely enjoyed fresh air. Many coastal cities dumped their garbage at sea.
To reduce fire, vermin, and odor, cities have converted open dumps to sanitary landfills, which has reduced some environmental problems but aggravated
others. Landfill toxic materials are leached by groundwater, polluting it. This consequence, plus problems such as health problems associated with chemical
landfills in populated areas, heightened public concern. In response to these concerns, the U.S. government has passed several laws and regulations that
control handling of toxic substances.
As landfills run out of space, new ones are difficult to create. People may support the creation of a facility, but they may not want it near their own homes.
This attitude is sometimes called the NIMBY attitude—for “not in my back yard.” Most people agree that landfills are needed, but few want them near their
homes. Stricter regulations have forced some landfills to close and have prevented others from opening. The number of operating landfills in the United
States has declined from about 30,000 in 1976 to fewer than 1,800 today. The few remaining landfills continue to grow as they accept the waste that formerly
went to other sites.
At the Roosevelt Regional Landfill, an innovative project is operating in which garbage is burned to produce electricity (Figure 9-8). The CO2 produced in
the process is sold to nearby greenhouses that formerly burned propane to increase the CO2 levels that accelerate plant growth in the greenhouses. This is
encouraging: An industry that disposes of unwanted things also sells a commodity that people need. In this case, not only are we producing electricity but
doing it in a way that reduces greenhouse gas emissions.
Figure 9-8 The Roosevelt Regional Landfill, Washington.
This landfill is the site of an innovative program to convert waste to electricity, thereby reducing the need for combustion of fossil fuels for that purpose.
In addition, the carbon dioxide produced from the landfill will be delivered to greenhouses that otherwise would burn propane to stimulate plant growth
by increasing the CO2 concentrations in the greenhouses.
AP Photo/ Yakima Herald Republic, Kirk Hirota)
9 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
Modern facilities such as this are expensive, as is the process of collecting waste and transporting it to landfills. Unfortunately, in many parts of the world,
the cost of collecting and disposing of solid waste is too high for society to bear. In our global economy, modern mass-produced materials are ubiquitous and
inexpensive, so solid waste is becoming a major problem in many poor countries. The most visible example of this is the presence of plastic bags, which
have replaced paper bags, baskets, and other biodegradable containers in rich and poor countries alike. Where solid waste collection is absent, plastic bags
and other nondegradable waste accumulates wherever people congregate (Figure 9-9).
Figure 9-9 Plastic bags litter a beach in Mumbai, India.
These bags are very inexpensive, which makes them easy to obtain, and they are difficult to recycle, making them a solid waste problem worldwide.
AP Photo/Rajesh Nirgude
Today, landfills are a scarce resource that must be used carefully. To slow the rate of filling, many landfills no longer accept grass clippings and leaves,
which can be composted (decomposed harmlessly) at home, or any other materials that can be recycled.
Energy Resources
Earth has bountiful and varied sources of renewable energy that humans have been able to harness:
Solar energy comes from the Sun.
Hydroelectric power and wind power come from natural movements of water and air caused by solar energy and gravity.
Geothermal energy comes from Earth’s internal heat in volcanic areas, including California, Iceland, and New Zealand.
However, most of the world’s energy comes from chemical energy stored in such substances as wood, coal, oil, natural gas, alcohol, and manure. Energy
is released by burning these materials. People burn these substances to heat homes, run factories, generate electricity, and operate motor vehicles. Most of
our energy comes from fossil fuels, but burning them reduces their supply—they are nonrenewable resources. We can continue to burn them for several
more decades, but they are the major cause of global warming. Regardless of that consequence, eventually we must switch to new energy resources if we
are to preserve our current standard of living.
Energy from Fossil Fuels
Oil, natural gas, and coal, known as fossil fuels, come from the remains of plants and animals buried millions of years ago. Through photosynthesis, plants
convert solar energy to the chemical energy stored in their tissues. When plants die, this energy remains in their tissues. The energy may be released
promptly if animals or decomposers consume the dead plants or if a fire burns the field or forest. Or the plants may become fossilized as coal, and the stored
energy may wait millions of years to be released when the coal is mined and burned.
Oil and gas are also stored sunlight. When we burn these fossil fuels today, we are releasing the energy originally stored in microscopic plants
(phytoplankton) millions of years ago. When animals eat plants, they store the energy that was incorporated into the plant tissues. As the sea’s countless
creatures died over thousands of years, their bodies sank to the bottom, creating organic sediment. Over time, this was converted to oil, accompanied by
natural gas. Coal, oil, and natural gas still are being created, but the processes are so slow that from a human perspective, fossil fuels are nonrenewable
resources: Once burned, they are gone forever as useful sources of energy.
From wood to coal, oil, and gas
From the time that humans first lived in North America—probably at the end of the last ice age about 18,000 years ago—until the mid-1800s, wood was the
most important source of energy. Prior to the arrival of European colonists, North American residents used wood almost exclusively for all of their needs, but
because their total population was small, they did not significantly deplete the resource. When Europeans arrived in North America beginning in the
seventeenth century, they harvested the forests for fuel and lumber and cleared the land for agriculture. By the end of the nineteenth century, most of the
forests near populated areas of the eastern United States had been cut down, and fuel wood became very expensive. It was also inadequate for providing
the large amounts of energy demanded by a growing industrial economy. Wood still provides the largest portion of energy in developing countries, though
supplies are dwindling in areas of dense, rural populations, such as in East Africa and southern Asia.
Coal served as a substitute for fuel wood during the nineteenth century. Although large amounts of coal have been consumed, abundant supplies still
remain in the United States and several other countries. Oil, another fossil fuel, was a minor resource until the diffusion of motor vehicles early in the 1900s.
Today, it is the world’s most important energy resource. A third fossil fuel, natural gas, once was burned off during oil drilling as a waste product because it
was too difficult to handle, and markets for it were not established. In recent years, however, it has become an important energy source. Today, these three
fossil fuels provide more than 85 percent of the world’s energy and more than 90 percent in relatively developed countries (Figure 9-10).
Figure 9-10 World energy sources, 2006.
10 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
Fossil fuels make up the major proportion of global energy production; renewable and nuclear energy are relatively minor.
Data from Energy Information Administration
For U.S. and Canadian industry today, the main energy resource is natural gas, followed by oil and coal. Some businesses directly burn coal in their
operations, while others rely on electricity generated primarily at coal-burning power plants. At home, electricity is used to operate diverse electrical devices,
and in some homes to generate heat and hot water. Natural gas is the most common source for home heating, followed by petroleum and electricity. Nearly
all transportation systems operate on petroleum products, including automobiles, trucks, buses, airplanes, and most railroads. Only subways, streetcars, and
some trains run on electricity, much of which is generated from burning fossil fuels.
Distribution of fossil fuels
Fossil fuels are not uniformly distributed beneath Earth’s surface (see Table 9-1). Mineral reserves are known deposits that can be extracted profitably using
current technology. Some regions have abundant reserves, whereas others have none. This distribution reflects how fossil fuels are formed. Coal forms in
swampy areas, rich in plants. The lush tropical wetlands of 250 million years ago are today the coal beds of the world, relocated to midlatitudes by the
ponderous movement of Earth’s tectonic plates (see Chapter 3). Oil and natural gas form in seafloor sediment, but Earth’s tectonic movements eventually
elevate some seafloor above sea level to become land. Today, we drill for petroleum on both land and the seafloor.
Table 9-1 Reserves of Oil, Natural Gas, and Coal
For each resource, only the top 15 countries are listed. The countries listed account for
92 percent of all oil reserves, 86 percent of all gas reserves, and 96 percent of all coal
reserves. Data are for 2009, except coal data, which are for 2005. Oil reserves for
Canada include tar sands.
Crude Oil (Billion
Barrels)
Natural Gas (Trillion
Cubic Feet)
Coal (Million Short
Tons)
Saudi Arabia
267
Russia
1,680 United States
263,781
Canada
178
Iran
992
Russia
173,074
Iran
136
Qatar
892
China
126,215
Iraq
115
Saudi Arabia
258
Australia
84,437
Kuwait
104
United States
238
India
62,278
Venezuela
99
United Arab
Emirates
214
South Africa
52,911
United Arab
Emirates
98
Nigeria
184
Ukraine
37,339
Russia
60
Venezuela
171
Kazakhstan
34,502
Libya
44
Algeria
159
Former Serbia and
Montenegro
15,306
Nigeria
36
Iraq
112
Poland
8,270
Kazakhstan
30
Indonesia
106
Brazil
7,791
United States
21
Turkmenistan
94
Colombia
7,671
China
16
Kazakhstan
85
Germany
7,394
Qatar
15
Malaysia
83
Canada
7,251
Brazil
13
Norway
82
Czech Republic
4,962
Source: Energy Information Administration, Oil and Gas Journal
Because minerals are available only in specific geologic environments, their distribution is very uneven. Table 9-1 reveals that, like the minerals shown in
Figure 9-5, fossil fuel resources are highly concentrated in a few places. For each of the fossil fuels listed, the top five countries hold more than 60 percent of
world reserves.
Relatively wealthy developed countries—which comprise about one-fourth of the world’s population—possess more than 60 percent of the world’s coal and
11 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
more than 60 percent of natural gas. China is the leading producer of coal, but the United States is also a major coal producer and user. Russia is the leading
producer of natural gas. Other than China and India, which have significant coal deposits, most countries in Africa, Asia, and Latin America have few
reserves of coal or natural gas.
The distribution of oil is somewhat different. Two-thirds of the world’s oil reserves are in the Middle East, including one-fourth in Saudi Arabia. Mexico and
Venezuela also have extensive oil fields. In contrast, oil reserves in North America and Europe are relatively small, and production in those regions has
passed its peak.
Compared to other continents, North America and Europe have much higher per capita oil consumption rates, so they account for nearly two-thirds of the
world’s energy consumption. The United States, with less than 5 percent of the world’s population, consumes nearly 20 percent of the world’s commercial
energy. In North America and Europe, the high level of energy consumption supports a lifestyle rich in food, goods, services, comfort, education, and travel.
Because relatively rich developed countries consume more energy than they produce, they must import energy, especially oil, from developing countries.
The United States imports roughly half of its needs, Western European countries more than half, and Japan more than 90 percent. U.S. dependency on
foreign oil began in the 1950s, when oil companies determined that the cost of extracting domestic oil had become higher than for foreign sources. U.S. oil
imports have increased from 14 percent of total consumption in 1954 to 62 percent in 2009. European countries and Japan increasingly depend on foreign oil
because of limited domestic supplies.
Oil production and price history
Layered Thematic World: Economic Petroleum Production
Early in the twentieth century, the United States was an oil exporter, but its needs soon exceeded domestic supplies. Europe has always been a net
importer of oil. In their search for cheaper oil, U.S. and Western European companies drilled for oil in the Middle East and sold it inexpensively to consumers
in relatively developed countries. Western companies set oil prices and paid the Middle Eastern governments a small percentage of their oil profits. To
reduce dependency on Western companies, the countries possessing oil created the Organization of Petroleum Exporting Countries (OPEC) in 1960. Today,
OPEC members include eight countries in the Middle East (Algeria, Iran, Iraq, Kuwait, Libya, Qatar, Saudi Arabia, and United Arab Emirates), plus Venezuela
in South America, Gabon and Nigeria in Africa, and Indonesia in Asia.
In the 1950s and 1960s, Western oil consumption and dependence on oil exporting nations grew. By the early 1970s, 35 percent of U.S. oil consumed was
imported—a low figure by modern standards but historically high at the time. The cost of those imports was low, typically around $3 per barrel (equivalent to
about $15 in 2010). OPEC nations were eager to establish control of oil production and pricing, and the 1973 war between Israel and its Arab neighbors
provided an opportunity for OPEC to assert itself. Angry at the United States and Western Europe for supporting Israel, OPEC’s Arab members organized an
oil embargo during the winter of 1973–1974. OPEC states either refused to sell oil to countries that had supported Israel or would sell only at significantly
inflated prices. Soon gasoline supplies dwindled in relatively developed countries, and prices at U.S. gas pumps soared. Another oil crisis followed in 1979,
triggered by a revolution in Iran. World oil prices went from $3 per barrel (160 liters, or 42 gallons) in 1974 to more than $35 in 1981 (Figure 9-11). To import
oil, U.S. consumers spent $3 billion in 1970 and $80 billion in 1980, nearly 3 percent of the gross national income (GNI). This rapid price increase abruptly
halted the rise in energy use in the United States and elsewhere and caused severe economic problems in relatively developed countries during the 1970s
and 1980s (Figure 9-12).
Figure 9-11 Crude oil prices, 1970–2009.
Based on U.S. refiner acquisition cost for imported crude oil since 1973; price of Saudi Light Crude for 1970–1973. Crude oil prices jumped sharply in
1973–1974, 1979–1981, and 2006–2008 but dropped dramatically in the mid-1980s and 2009. Prices in mid-2008 were at record high levels, but by
mid-2009, after adjustment for inflation, they were lower than they were in the early 1980s.
Data from Energy Information Administration
Figure 9-12 Trends in U.S. energy use, 1949–2008.
12 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
Fossil fuels make up the major proportion of energy consumed in the United States. Use of oil and natural gas increased rapidly from the 1950s to the
1970s, but growth has been much slower since the energy crises of 1974 and 1979.
Data from U.S. Energy Information Administration
In each of these oil crises, long lines formed at gas stations in the United States, and some motorists waited all night for fuel (Figure 9-13). In some cases,
gasoline was rationed by license plate number; cars with licenses ending in an odd number could buy only on odd-numbered days. Some countries took
more drastic action; the Netherlands banned all but emergency motor vehicle travel on Sundays.
Figure 9-13 Gas line in 1970s.
Cars lined up for gas in California during the oil crisis in 1979.
Larry Lee Photography/CORBIS
Developing countries were especially hurt by the price rises. They had depended on low-cost oil imports to spur industrial growth and could not afford
higher oil prices. Relatively wealthy developed countries somewhat lessened the impact of higher oil prices on their economies by encouraging OPEC
countries to return some of their money by investing it in real estate, banks, and other assets in North America and Western Europe. Poorer nations could not
offer this opportunity for reinvesting oil wealth.
No sooner had the world begun to adjust to high energy prices than the trend was reversed. Energy conservation measures in consuming countries
reduced demand. Internal conflicts weakened OPEC’s influence: Iraq and Iran fought a war that lasted eight years, and in the early 1980s, some OPEC
members broke ranks and reduced oil prices. The price of oil plummeted from more than $30 to around $10 per barrel. Exporting countries flooded the world
market with more oil in an unsuccessful attempt to maintain the same level of revenues as they had received during the 1970s. While supplies increased,
demand in relatively developed countries remained lower than before the boycott. Oil prices briefly spiked during the 1991 Persian Gulf War but then quickly
dropped back to about $20. In early 1998, following a significant drop in oil prices, OPEC members agreed to reduce production in an attempt to drive prices
back up, and by late 2000 prices were again above $30 per barrel. They fell back to about $20 by late 2001, falling particularly sharply after September 11,
2001, but then rose again as tensions mounted in Iraq. The steep rise that began in 2003 was certainly influenced by supply disruptions in Iraq, but it also
reflects growing worldwide demand for oil, especially in rapidly growing economies such as India and China. While there had been a significant reserve
productive capacity for the last two decades of the twentieth century, that capacity has virtually disappeared so that any significant disruption of supply
causes a rise in prices. In this environment, prices rose dramatically from 2003 to 2008, peaking at about $135 in July 2008. When the financial crisis struck
in late 2008 and major economies around the world went into recession, oil prices dropped almost 75 percent in a six-month period.
The recent pattern of a rapid rise in oil prices followed by global economic recession is remarkably similar to that of the late 1970s and early 1980s,
although the causes and circumstances are quite different. In the 1980s and 1990s, the world saw a prolonged period of relatively low oil prices. If rapid
economic growth and expansion in numbers of automobiles continues in south and east Asia as it has in recent years, then oil prices are not likely to remain
low for very long.
Future of fossil fuels
13 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
How much of the fossil fuels remain? Geologists can estimate fairly accurately the proven reserves of fossil fuels available in fields that have been explored,
but there are significant differences of opinion on potential reserves of the fossil fuels—the amount in fields not yet discovered and explored, and the actual
amount we will extract before shifting to other energy sources (see the Rapid Change box). The price spike of 2007–2008 shows that in the coming years,
global oil markets are likely to be increasingly strained by growing demand and production limitations.
Rapid Change: Peak Oil
If we divide Earth’s current proven oil reserves (about 1,000 billion barrels) by current annual consumption (about 24 billion barrels), we get
about 40 years of oil supply remaining. Rates of consumption will change, and new reserves will be discovered, but today’s proven oil
reserves will probably last only a few decades. Thus, unless large potential reserves are discovered, Earth’s oil reserves will be significantly
depleted during the twenty-first century, possibly in your lifetime.
Every discovery of new deposits extends the life of the resource. But extracting oil is becoming harder—and therefore more expensive. When
geologists seek oil, they look first to accessible areas where geologic conditions favor accumulation. The largest, most accessible deposits
already have been exploited. Newly discovered reserves generally are smaller and more remote, such as beneath the seafloor, where
extraction is costly. Exploration cost also has increased because methods are more elaborate and the probability of finding new reserves is
less.
At some point, the cost of finding and extracting oil will become so high that other sources of energy will be more attractive. When that
happens, we will begin to shift our energy infrastructure toward the new energy source(s), and the demand for oil will begin to drop, reducing
prices below what it costs to extract the oil. When that happens, oil production will reach a peak and begin a decline. These ideas were first
developed by a geologist named M. King Hubbert, and their application to the current world oil situation has become known as peak oil.
If we accept that a peak must happen sometime, the key question is: when? It is a critical question because when it happens, there will be a
fundamental transformation of our energy economy and all the machines and businesses that it. If the peak were to happen, say, 5 or 10
years from now, we want to know now so that we can prepare accordingly.
Some argue that the peak will occur very soon—in the next few years. These individuals, sometimes referred to as “peakists,” point to
declining production in major oil-producing regions such as the United States and the North Sea, and suggest that previous estimates of oil
reserves may have been too high. Others, such as those associated with the oil industry, argue that undiscovered or undeveloped oil fields
are many and that higher prices will spur development of these resources and provide oil for at least a few decades into the future.
Interestingly, each of these predictions can be self-fulfilling. If we believe that the peak will occur very soon, then we will avoid investing in
things that use oil. For example, we wouldn’t build a new gas station but instead we might build charging facilities in parking lots for plug-in
electric vehicles. Once we begin to invest in alternative energy technologies, economies of scale will begin to make these technologies more
affordable, and the transition away from oil will be under way. On the other hand, if we believe that oil will be with us for 20 or 30 years at
least, then we will go ahead and build that gas station and the gasoline-powered cars that will use it, and people will pay the higher prices
necessary to keep driving their cars. In this way, the debate over a technical question of “how much oil is left” actually becomes a policy
debate with very real consequences. Not surprisingly, those concerned about greenhouse gas emissions and arguing for a change to new
energy sources tend to be peakists, and those arguing for continuing a carbon-based economy tend to argue that there is plenty of oil still to
be developed.
If we are to continue to base our economies on fossil fuels, what new sources of oil are available? Because much of the oil in accessible places on land
has already been discovered and is being exploited today, future oil discoveries are likely to come from offshore areas and remote regions such as the Arctic.
Offshore oil operations have moved into deeper water in recent years, and the risks of this expansion became clear when the Deepwater horizon oil rig
exploded in the Gulf of Mexico in April of 2010 (Figure 9-14). The disaster produced the largest oil spill in U.S. history, and will likely result in more stringent
restrictions and higher costs associated with future offshore oil operations.
Figure 9-14 Deepwater Horizon.
The oil rig exploded and sank in April 2010, causing the worst oil spill in US history.
USCG
In addition to oil resources in remote locations, unconventional sources of oil are being studied and developed, such as oil shale and tar sandstones. Oil
shale is a “rock that burns” because of its tar-like content. Tar sandstones are saturated with a thick petroleum. Utah, Wyoming, and Colorado contain large
amounts of oil in shale, more than 10 times the conventional oil reserves found in Saudi Arabia. The United States also has very large coal reserves, and
technology that can convert coal to a liquid fuel is well developed. Canada has very large tar sandstone deposits that are currently being exploited. The
largest operation is in northeast Alberta, where the sands are mined and oil is extracted. A new pipeline will carry this oil across the Rocky Mountains to a
seaport on the Pacific near Vancouver, from which it can be shipped anywhere in the world.
The major concern about these unconventional resources is that converting them to liquid fuel that we can use in automobiles involves substantial carbon
dioxide emissions. A unit of liquid fuel derived from tar sands, for example, would result in perhaps 40 percent more CO2 emissions than a unit of fuel derived
14 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
from conventional crude oil. In addition, mining large quantities of rock in order to extract the hydrocarbons and then disposing of the waste is highly
destructive to the environment. Because of these environmental concerns, it is unlikely that unconventional oil resources will make a major contribution to
global energy needs in the near future.
Natural gas and coal: Short-term oil substitutes
In searching for alternatives to oil, we look first to the other two major fossil fuels—natural gas and coal. Natural gas is important in the United States as the
clean-burning fuel of choice to heat more than half of the country’s homes. A 1.6-million-kilometer (1-million-mile) pipeline network efficiently distributes gas
from production areas in the Gulf Coast, Oklahoma, and Appalachia to the rest of the country. Demand for natural gas is increasing, in large part due to air
pollution considerations.
Natural gas has its limitations, however. At current rates of consumption, natural gas reserves would last for 60 years, although potential reserves may be
greater than for oil. Russia and the Middle East have about two-thirds of the world’s natural gas reserves; the United States has only a few years of domestic
gas reserves. Therefore, continued intensive use of gas will depend on increased imports.
Coal reserves are more abundant than oil or natural gas and, at current rates of use, can provide nearly 400 years of proven reserves to the world. The
United States has a large percentage of the world’s coal reserves. Coal is used mainly to produce electricity, and our use of electricity is expanding much
faster than our use of other forms of energy. But several problems hinder expanded use of coal:
Air pollution. Uncontrolled burning of coal releases sulfur oxides, nitrogen oxides, hydrocarbons, carbon dioxide, and particulates into the atmosphere.
The sulfur and nitrogen oxides are a major component of acid deposition. Acid deposition occurs when sulfur and nitrogen oxides combine with water to
form acidic precipitation or when these acids are formed in the soil from pollutants that settle from the atmosphere. Many communities suffered from
coal-polluted air earlier in this century and encouraged their industries to switch to natural gas and oil. The Clean Air Act now requires utilities to use
low-sulfur coals or to install emission-control devices on smokestacks. Coal-fired power plants still pump large amounts of carbon dioxide into the
atmosphere. In 2009, the U.S. Environmental Protection Agency recognized CO2 as a pollutant that, as a greenhouse gas, “may reasonably be
anticipated to endanger public health or welfare” and is thus subject to regulation.
Land and water impacts. Both surface mining and underground mining cause environmental damage, an externality caused by burning coal. The
damage from surface mining is visible: Vegetation, soil, and rock are stripped away to expose the coal. Today, surface-mined land must be restored after
mining, but restoration may not leave the land as productive as it was before. Underground mining causes surface subsidence and can release acidic
groundwater.
Limited uses. Coal is a bulky solid, that cannot power cars, trucks, and buses without conversion to a liquid or gas. Coal-fired power plants can provide
the power to run electric vehicles, however, which are expected to become more common in the next few years.
Nuclear and Renewable Energy Resources
Where can we turn for energy that is safe, economical, nonpolluting, and widely available; is not controlled by a handful of countries; and does not contribute
to global warming? In the long run, we must look to energy sources that are renewable—or at least to resources such as nuclear energy that are so abundant
they are not likely to be depleted. The two most promising energy sources are nuclear and solar. Other alternatives at present include biomass and
hydroelectric power. We will now look at each of these sources.
Nuclear energy
Nuclear power can be generated either by fission (splitting an atom into two or more parts) or by fusion (joining two atoms together). Most peaceful
generation of nuclear power today relies on fission of uranium, although plutonium also can be used. Someday we may use fusion to generate nuclear
power, but as yet such technology is unavailable. Unlike solar or wind energy, nuclear energy is not renewable. It is derived from radioactive substances
mined from the earth—but a tremendous amount of energy is available from a small amount of material. A kilogram of nuclear fuel contains more than 2
million times the energy of a kilogram of coal.
The peaceful use of nuclear reactors to generate electricity began in the 1950s, and today about 400 reactors are operating around the world. Nuclear
power is used exclusively to generate electricity, a growing part of our energy needs. It supplies about one-third of all electricity in Europe. Japan (which has
virtually no fossil fuels), South Korea, and Taiwan also rely on nuclear-generated electricity (Figure 9-15). Nuclear power generates approximately 20 percent
of U.S. electricity (Figure 9-16). The United States derives a smaller portion of its energy from nuclear power than other wealthy developed nations, in part
because of its more abundant coal reserves.
Figure 9-15 World nuclear power, 2007.
15 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
Nuclear power plants are clustered in more developed wealthy regions, including Western Europe, North America, and Japan. Nuclear power has
been especially attractive in the United States (which produces about 30 percent of the world’s nuclear power) and in some European nations that lack
abundant reserves of petroleum and coal.
Data from Energy Information Administration
Figure 9-16 U.S. nuclear power.
Nuclear power is an important source of electricity in several states. Some locations have more than one nuclear reactor.
Like coal, nuclear power presents serious problems. These include potential accidents, the generation of radioactive waste, public opposition, and high
cost:
Potential accidents. A nuclear power plant cannot explode like a nuclear bomb, although it is possible to have a runaway chain reaction. The reactor
16 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
can overheat, causing a meltdown, possible steam explosions, and a scattering of radioactive material into the atmosphere. An explosion did occur in
1986, in a nuclear power plant at Chernobyl, Ukraine, near the border with Belarus. (Both countries at the time were part of the Soviet Union.) The
accident has caused over 3,500 deaths, including about 800 among emergency cleanup workers and potentially many more from subsequent cancers.
Cancer rates remain elevated in southern Belarus. For example, childhood thyroid cancer rates in Belarus increased from fewer than five per year
before the accident to more than 80 by 1994. The impact of this accident extended through Europe: Most European governments temporarily banned
the sale of milk and fresh vegetables because of possible contamination by radioactive fallout. In addition to accidental radioactive releases, many
people are concerned about potential terrorist attacks involving either nuclear weapons or “dirty” bombs composed of radioactive materials.
Radioactive waste. The uranium-based fuel used in nuclear reactors eventually is broken down to the point that it is no longer usable. However, waste
materials in this spent fuel remain highly radioactive for thousands of years. Spent fuel can also be reprocessed to extract plutonium, which can be used
in nuclear bombs. Pipes, concrete, and water near the fuel also become “hot” with radioactivity. This waste cannot be burned or chemically neutralized.
It must be isolated for several thousand years until it loses its radioactivity. Currently, spent fuel generated in the United States is stored in cooling tanks
at nuclear power plants, but these are nearly full. Work is under way to develop a long-term storage facility in Nevada, but many problems remain to be
solved before waste can be moved from temporary storage sites to a permanent facility. Kazakhstan, which already has radioactive waste storage and
disposal facilities dating from the Soviet era, is building a facility to receive nuclear waste from the European Union.
Public opposition. Public concern about safety has been an obstacle to the diffusion of nuclear power since the technology first emerged. The accident
at Chernobyl, as well as less damaging incidents in the United States and other countries, dramatically increased public concern about nuclear power
(Figure 9-17). At Shoreham, Long Island, near New York City, a nuclear power plant was ready to operate and begin generating electricity when, under
pressure from worried citizens, the government decided not to allow the plant to open and compensated the electric company for the loss of the plant. In
1992, Italian voters rejected future nuclear power development in that country, and public opposition is similarly strong in Germany and Scandinavia.
Even in France, where over 70 percent of electricity is generated from nuclear power, public opposition is a major barrier to new development. In
addition, nuclear power plants cannot operate without a reliable source of cooling water, and summer heat waves in 2003 and 2006 caused critical
cooling-water shortages in some areas of Western Europe.
Figure 9-17 China Syndrome.
This film, released on March 16, 1979, portrayed a fictional nuclear power plant near-meltdown that bore striking similarities to an incident just
12 days later at Three Mile Island, Pennsylvania. The film contributed to rising public fear of nuclear power.
COLUMBIA / THE KOBAL COLLECTION
High cost. Nuclear power plants cost several billion dollars to build, primarily because of elaborate safety measures. Without double and triple backup
systems, nuclear energy would be too dangerous to use. As a result, the cost of generating electricity is much higher from nuclear plants than from coal
plants.
Biomass
sidenote: Video
Gas, Gas, Gas
Biomass fuel derives mostly from burning wood but includes the processing of other plant material and animal waste. Energy is generated by either
burning directly or converting substances to charcoal, alcohol, or methane gas. Biomass provides most of the world’s energy consumption for home heating
and cooking, especially in the developing world. In China, some individual homes have fermentation tanks that convert waste to methane, which is used for
cooking and heating.
Forms of biomass, such as sugarcane, corn, and soybeans, can be processed into motor vehicle fuels; Brazil in particular makes extensive use of biomass
to fuel cars and trucks. When the price of oil rose rapidly in 2007 and 2008, the United States invested heavily in the production of biofuels using corn or
other crops as the feedstock. Dozens of new ethanol-producing plants were built, spurred by substantial government subsidies. Between 2002 and 2009,
U.S. ethanol production more than quadrupled. However, it takes a significant amount of land to produce the feedstock for biofuels, and a substantial
increase in biofuel production would require much more agricultural land than is currently available. Also, the amount of fuel energy that is produced to
manufacture ethanol from corn or biodiesel from soybeans is small, after one accounts for the amount of fuel consumed for tractor fuel and other needs in
producing the corn or soybeans. Some analyses even indicate that more fuel is used to grow the crops than is produced when the crops are converted to
fuel. When energy prices dropped dramatically in late 2008 and the price of corn remained relatively high, ethanol lost its competitive edge against gasoline
17 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
made from fossil fuels. By 2009, the boom in biofuel production had stopped. If oil prices rise again then biofuel will probably come back to life, but concerns
will remain about the wisdom of using crops to produce fuels when the net energy production is small.
The carbon and energy balances of biofuel production are potentially more favorable when based on crops that do not displace food products. There has
been much discussion of switchgrass as a source of biofuels. Switchgrass is a perennial grass native to North America that can produce high yields without
annual plowing and planting and the energy it requires. However, the biomass it produces is not as easily converted to biofuel as is that in crops such as corn
or soybeans, and economically efficient commercial-scale processes that would use switchgrass as a feedstock have not yet been developed.
Biomass-to-energy conversion is much more appealing when it also serves to dispose of wastes. Opportunities for converting waste to biofuels may grow.
In Bangladesh, for example, in 2003, a new pilot plant began generating electricity using the waste from 5,000 poultry farms. The concentration of U.S. meat
production in large feeding operations (see Chapter 8) means that manure is already concentrated and managed instead of being scattered over the ground
in barnyards. This increases the potential for using it to produce commercially valuable fuels. If the price of fossil fuels remains high, as seems likely, these
new forms of renewable energy production are likely to grow in importance. Used fats and oils are being converted to biodiesel in the United States, but the
quantities available are not sufficient to meet our enormous demand for motor fuels.
Hydroelectric power
Flowing water has been a source of mechanical power since before recorded history. In the past, water was used to turn a wheel that could operate
machines capable of grinding grain, sawing timber, and pumping water. Since the early 1900s, the energy of moving water has been used primarily to
generate electricity, called hydroelectric power. It supplies about one-fourth of the world’s electricity, which is more than any other source except for coal.
To generate hydroelectric power, water must abruptly change height, as at a dam. The falling water turns turbines that power electrical generators. A
hydroelectric plant produces clean, inexpensive electricity, and a reservoir behind the dam can be used for flood control, drinking water, irrigation, and
recreation.
Canada, China, Brazil, and the United States are the largest producers of hydroelectric power in the world. Together, North America and Europe generate
about half the world’s hydroelectric power. Hydropower supplies about 6 percent of total commercial energy production worldwide, but in the United States, it
supplies less than 3 percent and in Canada 9 percent of commercial energy consumption. Most of the best sites for hydroelectric generation are already in
use in the United States and Europe, but in many areas, there is considerable undeveloped potential. China, Brazil, Indonesia, Canada, and the Congo have
especially great hydroelectric potential.
Opposition to construction of big dams and reservoirs is strong among environmentalists who fear the environmental damage they cause, such as loss of
farmland or animal habitat. Hydroelectric dams may flood otherwise usable land and displace the people who lived on it. A dam converts a free-flowing
stream to a lake, thus altering aquatic life. Many good sites for generating hydroelectric power remain in the world, but political considerations restrict their
use, especially if the river flows through more than one country. For example, Turkey’s recently built dam on the Euphrates River was strongly opposed by
Syria and Iraq, through which the river also passes. They argue that the dam diverted too much water from the river and increased its salinity.
Despite these problems, hydroelectric power remains an attractive alternative to fossil- or nuclear-fueled power plants, largely because it generates no
pollution. In rapidly industrializing countries such as China, increased electricity generation can mean an increase in the standard of living not only in
industrial cities but in small towns where electricity provides clean energy for indoor cooking and lighting and operates pumps that help provide clean drinking
water. The case of the Three Gorges Dam, which has drawn much international criticism for its negative impacts on the environment and human settlements,
does have the advantage of providing a clean alternative to dirty coal-generated electricity.
Solar energy
Energy ultimately derived directly from the Sun offers much potential for providing the world’s energy needs in future centuries. The Sun is a nonpolluting and
perpetual source of energy that can be used directly or indirectly in forms such as wind and biomass.
At present, solar energy is used in two principal ways: thermal energy and photovoltaic electricity production. Solar thermal energy is heat collected from
sunshine. Collection may be achieved by designing buildings to capture the maximum amount of solar energy. Alternatively, special collectors may be placed
near a building or on the roof to gather sunlight. The heat absorbed by these collectors is then carried in water or other liquids to the places where it is
needed.
sidenote: Video
Smokeless in China
Photovoltaic electric production is a direct conversion of solar energy to electricity in photovoltaic cells. Each cell generates a small electric current, and
banks of them wired together can produce a large amount of electricity. Solar-generated electricity is now used widely, not only where conventional power is
unavailable but also as a replacement for some conventional electric power. As more photovoltaic cells are produced, and as their technology and efficiency
are improved, the cost of solar power will decline. Photovoltaic cells are already competitive with conventional energy sources in many new residential and
commercial installations.
Solar energy can be generated either at a central power station or in individual homes. Many countries are wired for central distribution, so central
generation by utilities makes sense. But solar power technology now makes feasible individual home systems. An installation costing several thousand
dollars provides a solar energy system that provides virtually all heat and electricity for a single home. Because the high installation price is offset by low
monthly operating costs, home-based solar energy is economical for consumers who remain in the same house for many years. Individual solar energy users
do not face rising electric bills from utilities that pass on their cost of purchasing fossil fuels and constructing facilities. The United States, Israel, and Japan
lead in solar use at home, mostly for heating water. Solar energy is likely to become more attractive as other energy sources become more expensive.
Wind energy
Wind generation of electricity is one of the fastest-growing renewable energy technologies today. Significant improvements in turbine efficiency in recent
years, combined with a growing demand for clean electricity, are making commercial-scale wind projects much more attractive. Large-scale wind-generating
facilities are popping up across the landscape in many areas (Figure 9-18). The output of wind-generated electricity in the United States tripled between 2003
18 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
and 2007, although it still amounts to less than 2 percent of the country’s total electricity production. Wind energy, economical and clean as it is, is not without
controversy, however. Environmentalists are divided: Some favor wind generation because it is renewable and pollution free, while others oppose it on the
grounds of its adverse visual impacts and its hazards to birds. For example, North Carolina has prohibited construction of large wind turbines on its higher
Appalachian ridges because of concerns about effects on the scenic beauty of the region. Nonetheless, the new growth in wind energy production signals a
significant trend in the shift toward renewable energy.
Figure 9-18 A wind farm in Illinois.
Production of wind energy has grown rapidly in much of the world but still accounts for only a minor part of total electricity production.
© VStock / Alamy
sidenote: Video
Payback Time
Transition to new energy sources
The world contains a variety of energy sources. In addition to fossil fuels, people make use of hydroelectric, biomass, solar, and nuclear power. Other
technologies are also in commercial use today, including geothermal, wind, and tidal power.
The emergence of new energy technologies suggests that we are beginning the transition from a fossil-based energy system to a new mix of energy
supplies. Oil and gas are likely to remain important for several decades, but they likely will diminish in importance relative to other resources, especially
renewable alternatives.
At present, the emerging energy sources are less versatile than oil and gas and are likely to find only specialized uses. Solar thermal energy might be used
to heat buildings, whereas photovoltaic cells can power small electrical appliances. Centralized electric power plants—coal, nuclear, or hydroelectric—will
probably remain the major source of energy for heavy users, such as large factories and shopping malls.
The United States has several options for meeting its energy needs. It might burn more coal, perhaps installing improved devices to protect against air
pollution. Nuclear energy might win new proponents. Conservation and renewable energy sources also offer much potential. But none of these alternatives to
coal and oil will grow significantly without the incentives provided by much higher energy prices. We can provide those incentives through government policy,
or we can wait for increasing global demand for oil to drive prices up, forcing us to find alternatives. In any case, oil is certain to become increasingly
expensive and less attractive as the basis of our economy.
If history is a reliable guide, the mechanism that will drive this transition to new energy supplies is the market. If the price of oil rises significantly, alternative
technologies that are currently uncompetitive would become attractive. As these new technologies are more extensively used, their prices will decrease,
further encouraging a shift away from oil.
Conservation is equivalent to discovering a new energy source, and in all likelihood, the greatest source of new energy resources will be conservation.
More efficient use of energy means that we can produce more goods, operate more motor vehicles, and heat more buildings with the same amount of
energy. Conservation is one factor in the slow growth of energy consumption since the 1970s. Sluggish demand for petroleum contributed to the decline in oil
prices in the 1980s; similarly, slow growth in electricity demand contributed to the demise of the nuclear power industry.
In mid-2008, as oil prices reached record levels, interest in energy conservation and alternative technologies grew dramatically, especially in the United
States. However, the economic downturn that struck in late 2008, combined with a major decline in oil prices, shifted the focus of concern away from energy.
Nonetheless, many of the measures developed to promote economic development have also encouraged conservation, such as programs that subsidized
replacement of older vehicles with newer more efficient ones, programs subsidizing home renovations to conserve energy, and subsidies for the development
of renewable energy sources. In the long run, however, the conversion to renewable energy will have to be driven by the relative costs of fossil fuels,
primarily oil, and renewable energy.
Air and Water Resources
19 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
In the preceding section, we considered renewable energy resources, which can be used year after year indefinitely. Renewable resources are limited in
availability, however, and some renewable resources can be degraded in quality. Air and water resources are vital to humans; we need them for life and we
also depend on them for waste removal. But in using air and water to carry away combustion products or animal wastes we degrade air and water quality.
Burning fossil fuels pumps carbon dioxide into the atmosphere. The sulfur from burning oil and coal also enters the atmosphere and returns as acid
deposition. Thus, the geography of resource consumption is also the geography of environmental pollution.
Air and water share two important properties: They are critical to human and other life on Earth, and they are useful places to deposit waste. An extreme
environmentalist may argue that we should not discharge any waste into air and water, but in practice, we need to rely on air and water to remove and
disperse some waste. Not all human actions harm the environment, and the air and water can accept some waste. For instance, when we wash chemicals
into a river, the river may dilute them until their concentration is insignificant. Pollution (elevated levels of impurities in the environment caused by human
activity) results when more waste is added than a resource can accommodate.
Pollution levels generally are greater where people are concentrated, especially in urban areas. When many people are clustered in a small area, the
amount of waste they generate is more likely to exceed the air and water’s capacity to accommodate it.
Air Pollution
The purity of air is paramount to life on Earth. Some air pollutants come from natural processes unrelated to human actions, such as dust, forest fire smoke,
and volcanic discharges. Humans add to this by discharging into the atmosphere smoke and gas from burning fossil fuels, incinerators, evaporating solvents,
and industrial processes.
The atmosphere is constantly stirred by temperature and pressure differences that mix vertically and horizontally. As it moves from one place to another,
air carries with it various wastes. The more waste we discharge to the atmosphere, or the less the air circulates, the greater the concentration of pollution.
Average air at the surface contains about 78 percent nitrogen, 21 percent oxygen, and less than 1 percent argon. The remaining 0.04 percent of air’s
composition includes several trace gases. Air pollution is a human-caused concentration of trace substances at a greater level than occurs in average air. In
addition to the carbon dioxide (CO2) emitted by “clean” combustion of fossil fuels, the most common air pollutants include carbon monoxide (CO), sulfur
oxides (SO x , where the subscript x stands for the number of oxygen atoms), nitrogen oxides (NO x ), hydrocarbons, and particulates (very small
particles of dust, ash, and other materials). Concentrations of these pollutants in the air can damage property and affect the health of people, other animals,
and plants (Figure 9-19).
Figure 9-19 Major human-caused air pollution sources in the United States, 2003.
Nationwide, particulates come mostly from soil erosion, but in urban areas they are derived from vehicles and industrial sources processes. Sulfur
oxides are mostly derived from industrial processes. Vehicles, mostly cars and trucks, are the most important source of carbon monoxide as well as a
major source of nitrogen oxides and hydrocarbons.
U.S. Census Bureau
Each pollutant entering the atmosphere behaves differently. For example,
SO x and NO x combine with water and fall to Earth as acid precipitation.
Particulates in smoke are cleansed from the atmosphere quickly by gravity and precipitation.
Photochemical smog—the product of hydrocarbons, as well as NO x and sunlight—is created by chemical reactions that occur in the atmosphere itself.
Chlorofluorocarbons (CFCs), chemicals used as refrigerants and in a variety of industrial applications, remain in the air long enough to be widely
dispersed and carried into the upper atmosphere, where they damage Earth’s protective ozone layer.
We are polluting our air in many ways today. We will focus on two important air pollution issues: acid deposition and urban air pollution.
Acid deposition
20 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
More commonly known as acid rain, acid deposition occurs when sulfur oxides and nitrogen oxides, produced mainly from burning fossil fuels, are
discharged into the atmosphere. The sulfur and nitrogen oxides combine with oxygen and water in the atmosphere to produce sulfuric acid and nitric acid.
When dissolved in water, the acids may fall as acid precipitation, or they may be deposited in dust. We use the term acid deposition to include both types of
pollution.
Acid deposition seriously damages lakes and kills fish and plants. But the most severe damage of acid deposition is to the soil. The acid deposits harm the
soil in a number of ways. Some of the acid deposited in soil is neutralized by calcium, magnesium, and other naturally present chemicals, but the amount of
acid deposited can exceed the capacity of the soil’s chemicals to neutralize the acid. If soil water grows too acidic, plant nutrients are leached away and are
unavailable to plants. Acid deposition can dissolve aluminum in the soil, which can be toxic to plants and interfere with their nutrient uptake. Acids may also
harm the soil-dwelling worms and insects that decompose organic matter.
Acid deposition is a regional problem, most severe in the densely populated industrial regions in Europe, eastern North America, and eastern Asia. It is a
major source of damage to forests, especially in the industrialized and densely populated regions of the eastern United States, Central Europe, and eastern
China, where high levels of SO x discharges combine with precipitation to form acids (Figure 9-20). Damage to individual forests varies widely, depending on
its age, tree species, the capacity of the soil to neutralize acids, and interactions between trees and other organisms in the forest (Figure 9-21). Because the
relationship between tree damage and high discharges of SO x and NO x has not been documented precisely, some governments are unwilling to impose the
cost of controlling emissions on their industries and consumers.
Figure 9-20 Acid deposition in North America.
Acid deposition problems are caused by both nitrate and sulfate. These maps show wet sulfate deposition rates in the conterminous United States, in
kg per hectare. The areas of North America most affected by acid deposition are in the Ohio Valley, eastern Great Lakes, and populated areas of the
eastern United States. Acid deposition from sulfate, the larger component of acid deposition, has declined significantly as a result of emissions
controls. Acid deposition from nitrate (not shown) has declined less, and has actually increased in some areas.
U.S. Environmental Protection Agency
Figure 9-21 Trees in the Black Forest, Germany,
This forest, in the heart of Europe’s industrial region, is suffering from decline probably caused by acid deposition.
Gernot Huber/Woodfin Camp&Associates, Inc.
21 of 32
9/9/14 10:39 PM
https://portal.phoenix.edu/medialibrary/embedreader.urn:isbn:9780...
Nonetheless, significant progress has been made. Since the early 1970s, the United States has reduced SO x emissions about 47 percent. Over this same
time period, emissions have been cut by larger percentages in other relatively wealthy developed countries, including 60 percent in Canada, 84 percent in
France, 92 percent in Germany, and 92 percent in Sweden. NO x emissions, which are more difficult than SO x to control, have remained at about the same
level in the United States during the past quarter century. Although precise figures are not available, SO x emissions have probably increased in developing
countries, especially China, which is responsible for nearly one-fourth of the world’s coal combustion, the major source of SO x emissions. China’s sulfur
emissions are a major source of acid deposition in Japan, again borne by prevailing westerly winds. In an attempt to reduce this problem, Japan is helping
pay for the installation of pollution-control equipment in China.
Urban air pollution
Urban air pollution results when a large volume of emissions is discharged into a small area. The problem is aggravated in cities when the wind cannot
disperse these pollutants. Urban air pollution has three basic components:
1. Proper burning in power plants and vehicles produces carbon dioxide (CO2), but incomplete combustion produces carbon monoxide (CO). Breathing CO
reduces the oxygen level in blood, impairing vision and alertness and threatening persons who have chronic respiratory problems.
2. Hydrocarbons also result from improper fuel combustion, as well as from evaporation of solvents as in paint. Hydrocarbons and NO x in the presence of
sunlight form photochemical smog, which causes respiratory problems and stinging in the eyes.
3. Particulates include dust and smoke particles. You can see particulates as a dark plume of smoke emitted from a smoke stack or a diesel truck—not a
white plume, which is condensed water vapor. Many particles are too small to see, however.
Three weather factors are critical to urban air pollution:
1. When the wind blows, it disperses pollutants. When the air is calm, pollutant concentrations build up.
2. Air temperature normally drops rapidly with increasing altitude. But over cities, conditions sometimes cause temperature inversions, in which warmer
air lies above cooler air. This limits vertical circulation, trapping pollutants near the surface (Figure 9-22).
Figure 9-22 A normal temperature profile (a) and a temperature inversion (b) above a city.
The temperature inversion traps pollutants.
From R. W. Christopherson, Geosystems, 3rd ed. Upper Saddle River, NJ: Prentice Hall, Inc., 1997.
3. Sunlight is the catalyst for smog formation.
As a result of these three factors, the worst urban air pollution occurs under a stationary high-pressure cell, where a combination of slight winds,
temperature inversions formed by descending air, and clear skies allow pollutants to accumulate. A city that experiences frequent stationary highs, such as
Denver, Colorado, has frequent pollution problems.
Mexico City is notorious for severe air pollution, especially in winter, when high pressure often dominates, and the surrounding mountains discourage
dispersal of pollutants by wind (Figure 9-23). In the eastern United States, pollution problems are worst in summer and autumn, because stationary highs are
most common then. In West Coast cities such as Los Angeles and San Francisco, the pollution “season” is also summer and autumn because inversions and
bright sunshine are more persistent then.
Figure 9-23 Mexico City suffers from a combination of circumstances tha...
Purchase answer to see full
attachment
User generated content is uploaded by users for the purposes of learning and should be used following Studypool's honor code & terms of service.
Reviews, comments, and love from our customers and community: