second largest energy cost associated with agriculture. The use of fuel-requiring pumps to irrigate crops is also a major energy consumer. Additional energy is used in food processing, distribution, storage, and cooking after the crop leaves the farm. The energy used for these activities may be five times as much as that used to produce the crop. Current Trends in Agriculture The development of biofuels, fuels produced from plants, such as corn and soy ethanol and cellulosic ethanol (produced from inedible portions of plants), has been encouraged by the need to find a substitute for expensive and environmentally harmful fossil fu- els. However, the fluctuating price of oil has caused this industry to advance in fits and starts. Critics point out that biofuels use cropland that otherwise would be producing food, and the rise of the electric car could speed the decline in the use of fossil fuels, mak- ing biofuels obsolete. The next major development in agriculture will be the biotechnical revolution, in which scientists will be able to use molecular biological techniques to pro- duce exotic new crop varieties. In the future, perhaps agricultural scientists will be able to use these tech- niques to develop crop plants that can be produced, processed, and distributed with less impact on other resources. Many scientists feel nanotechnology, the ability to restructure matter at the level of molecules and atoms, could meet the needfor growth inagricul- ture through improving the production of both plants and animals and improving both the safety and qual- ity of food.A wide range ofdeveloped and developing countries, from the United Kingdom to Iran to India, are providing funding to scientific laboratories to de- velop nanotechnology products. The potential prod- ucts range from antibacterial agents to technology that signals when a product is near the end of its shelf life. There remains concern that including nanopar- ticles in food may pose a health risk, and consumer advocates are encouraging more research, consumer awareness, and governance. The trend toward globalization in agriculture has been good for the developed countries, but it poses a threat to developing nations. For example, countries in Africa do not benefit from the advances in global agriculture. Rural dwellers have neither the money nor the natural resources to take advantage of mod - ern agricultural methods. At the same time, the agri - cultural practices in the developed world bring with them many negative consequences for the environ - ment. Water pollution from fertilizers and pesticides; global warming from increasing land under cultiva- tion and decreasing forests; and decreased diversityof agricultural productsinspecificregions,whichresults in increased energy use to get these products to their global markets. Interest in organic farming, which is practiced in more than one hundred countries, offers opportunities for organic farmers from developing countries. However, if organic farming follows the pattern of commercial agriculture, withthe growth of large farms, specialized products, and need for in- creasing capital, the benefit to the small, local farmer will disappear andtheenvironmentalimpact will turn negative. Commercial Impact of the Agriculture Industry Worldwide, some 45 percent of the population makes a living through agriculture, both subsistence and commercial. This also includes those people hired by the agriculture chemical companies, those compa- nies that produce or sell agriculture implements and machinery, processing and canning plants, and whole- sale and retail marketing firms, such as grocery stores. There are some eight thousand different agricultural products on the market, and while agriculture is big business, it amounts to less than 5 percent of the gross domestic product of all nations. Approximately one- third of the land worldwide is used for agriculture. D. R. Gossett Further Reading Akinyemi, Okoro M. Agricultural Production: Organic and Conventional Systems. Enfield, N.H.: Science Publishers, 2007. Brody, Aaron L., and John B. Lord, eds. Developing New Food Products fora Changing Marketplace. 2ded. Boca Raton, Fla.: CRC Press/Taylor & Francis, 2008. Field, Thomas G., and Robert E. Taylor. Scientific Farm Animal Production: An Introduction to Animal Science. 9th ed. Upper Saddle River, N.J.: Prentice Hall, 2008. Janick, Jules. Horticultural Science. 4th ed. New York: W. H. Freeman, 1986. Kipps, M. S. Production of Field Crops: A Textbook of Agronomy. 6th ed. New York: McGraw-Hill, 1970. Metcalfe, Darrel S., and Donald M. Elkins. Crop Pro - duction: Principles and Practices. 4th ed. New York: Macmillan, 1980. 20 • Agriculture industry Global Resources Southgate, Douglas, Douglas H. Graham, and Luther Tweeten. The World Food Economy. Malden, Mass.: Blackwell, 2007. Weis, Tony. The Global Food Economy: The Battle for the Future of Farming. New York: Zed Books, 2007. Wojtkowski, Paul A. Agroecological Economics: Sustain- ability and Biodiversity. Boston: Elsevier/Academic Press, 2008. Web Sites Agriculture and Agri-Food Canada Agri-Industries http://www4.agr.gc.ca/AAFC-AAC/display- afficher.do?id=1166532974345&lang=eng U.S. Department of Agriculture Agriculture http://www.usda.gov/wps/portal/!ut/p/_s.7_0_A/ 7_0_1OB?navtype=SU&navid=AGRICULTURE See also: Agricultural products; Animal breeding; Animal domestication; Biofuels; Corn; Cotton; Flax; Forestry; Forests; Genetic prospecting; Global Strat- egy for Plant Conservation; Green Revolution; Hemp; Horticulture; Land ethic; Monoculture agriculture; Plant domestication and breeding; Plant fibers; Rice; Rubber, natural; Seed Savers Exchange; Slash-and- burn agriculture; Soil; Svalbard Global Seed Vault; United Nations Food and Agriculture Organization; Wheat; Wood and timber. Agronomy Categories: Scientific disciplines; environment, conservation, and resource management Agronomy comprises a group of applied-science disci- plines concerned with land and soil management and crop production. Agronomists’ areas of interest range from soil chemistry to soil-plant relationships to land reclamation. Definition There are multiple definitions of agronomy, as befits a discipline with many different facets. The Oxford Universal Dictionary defines agronomy as “the study of land management or rural economy”; Merriam- Webster’s Collegiate Dictionary calls it “a branch of agri - culture dealing with field-crop production and soil management.” The word derives from the ancient Greek agros (field) and nemein (manage): field man- agement. Thus the American Society of Agronomy defines agronomy as “the theory and practice of crop production and soil management.” Overview Agronomy is essentially the discipline or disciplines that investigate the production of crops supplying food, forage, and fiber for human and animal use and that study the stewardship of the soil from which those crops are grown. Agronomy covers all aspects of the agricultural environment, from agroclimatology to soil-plant relationships; crop science; soil science; weed science; biometry (the statistics of living things); crop, soil, pasture, and range management; crop, for- age, and pasture production and utilization; turf- grass; and agronomic modeling. Within each area are subdisciplines. For example, within soil science are traditional disciplines suchas soil fertility, soil chemis- try, soil physics, soil microbiology, soil taxonomy and classification, and pedogenesis (the science of how soils form). Newer disciplines within soil science in- clude such studies as bioremediation, or the study of how living organisms can be used to clean up toxic wastes in the environment, and land reclamation, the study of how to reconstruct landscapes disturbed by human activities such as surface mining. Agronomy treats the agricultural environment as humankind’s greatest natural resource: It is the source of our food, the source of our clothing, the source of our building materials, and the environment that purifies the air we breathe and the water we drink. Agronomists, whatever their specific field, utilize the soil resources and plant resources around them to benefit society. Crop breeders, for example, use the genetic diversity of wild varieties of domesticated plants to obtain the genetic information needed to breed plants for greater productivity or pest resis- tance. Soil scientists study landscapes to determine how best to manage the soil resource by integrating agricultural practices with the environment in terms of maintaining soil fertility and in terms of keeping soil in place so that erosion does not reduce the qual- ity of the surrounding environment. Poor field management leads to reduced produc- tivity and reduced environmental quality. Historical examples abound,ranging from the1930’s DustBowl in theUnited States to the deforestation onthe island Global Resources Agronomy • 21 of Madagascar in the late twentieth century. It is the role of agronomy to manage soil and crop resources as effectively as possible so that the twin goals of pro- ductivity and environmental quality are preserved. Mark S. Coyne See also: Dust Bowl; Erosion and erosion control; Farmland; Fertilizers; Monoculture agriculture; Rangeland; Slash-and-burn agriculture; Soil; Soil test- ing and analysis; Wheat. Air pollution and air pollution control Category: Pollution and waste disposal An air pollutant is any substance added to the atmo- sphere by human activities that affects humans, ani- mals, or the environment adversely. Many pollutants are toxic, while seemingly benign emissions such as carbon dioxide, a major contributor to global warm- ing, and chlorofluorocarbons, which decimate the stratospheric ozone layer, are dangerous inless obvious ways. Significant worldwide resources have been com- mitted to reducing all such hazardous emissions. Background Air pollution, occurring in gaseous, particulate, or aerosol form, has been problematic since humans began living in large cities and burning carbon-based fuels. The first known air pollution ordinance was passed in London in 1273, in an attempt to alleviate the soot-blackened skies from excessive combustion of wood. From the mid-eighteenth century through the mid-twentieth century, the increasingly heavy use of coal for heat, electricity, and transportation re- sulted in filthy air and an escalation of respiratory diseases. In the latter half of the twentieth century, governments began attacking the problem with legis- lation to control noxious emissions at their source. Earth’s atmosphere consists primarily of nitrogen, oxygen, water vapor,andtraceamountsofmanyother substances. Emissions from human activities can alter the concentrations ofthese substances or release nox- ious chemicals with serious implications—including smog, acid rain, the greenhouse effect, and holes in the ozone layer—for both human and planetary health. The major air pollutants are carbon oxides, sulfur oxides, nitrogen oxides, hydrocarbons, and particu- late matter. Each year the United States adds more than 5.5 billion metric tons of carbon dioxide (CO 2 ) to the air; China adds approximately 6 billion metric tons. Worldwide, the amount of CO 2 inserted into the atmosphere exceeds 28 billion metric tons annually, contributed in roughly equal proportions by fossil- fuel electric power plants, industry, transportation, and homes and businesses. Air Pollutants CO 2 results whenever a carbon-containingfuel—such as coal, oil, or gasoline—is burned. When combustion is incomplete carbon monoxide (CO) is also pro- duced. Although CO 2 is a relatively benign compound, the vast amount of fossil fuels (coal, oil, and natural gas) burned since the Industrial Revolution has in- creased the atmospheric amount by about 40 percent and continues to increase at an escalating rate. Car- bon dioxide molecules, while transparent in visible light from the Sun, reflect infrared radiation emitted by Earth and reradiate it as heat. Eventually, this will likely raise Earth’s average temperature in proportion to the amount of atmospheric CO 2 . This “greenhouse effect” poses a long-term risk because a warming trend could increase sea levels, change rainfall pat- terns, disrupt grain belts, cause storms of greater in- tensity, and shift climate zones. Carbon monoxide is a toxic compound that causes death by suffocation by replacing oxygen in the bloodstream, thus depriving cells of their necessary oxygen. Sulfur oxides are created wheneverfossilfuels,par- ticularly coal containing sulfur, are burned. Inhaling even relatively small concentrationsof these gases can damage the upper respiratory tract and lung tissue. Another problem isthatthey react with watervaporin the atmosphere to produce sulfuric acid, a major component in acid rain. Nitrogen oxides are synthesized whenever air is rapidly heated under pressure, followed by quick cooling, such as occurs in internal combustion en- gines and thermoelectric power plants. These com- pounds play a major role in the formation ofacidrain, photochemical smog, and ozone (O 3 ), a potent reac- tive compound that attacks the lungs. Combustion- caused ozone is dangerous to living organisms near Earth’s surface, but in the stratosphere itoccurs natu - rally. This “ozone layer” prevents most of the Sun’s ul - traviolet light from reaching Earth’s surface. There - 22 • Air pollution and air pollution control Global Resources fore, it can cause skin cancer in humans as well as affect plants and wildlife adversely. Particulates are minuscule solid or liquid particles suspended in the air. They occur from combustion, dry grinding processes, and spraying. The human re- spiratory system has evolved a mechanism to prevent certain sizes of particulates from reaching the lungs, but there is no protection againstthesmallerparticles of coal dust and the larger particulates in tobacco smoke. Coal dust settling in the lungs leads to black lung disease, while the particulates from tobacco smoke are a leading cause of lung cancer. The United States emits millions of metric tons of suspended particulate matter each year, chiefly from fossil-fuel electric power plants and industrial smelt- ing plants. Even particulates that do not reach the lower regions of the respiratory tract can affect breath- ing, cause emphysema, aggravate an existing cardio- vascular disorder, or damage the immune system. Smog The word “smog” is a meldingof “smoke” and“fog” to describe fog polluted by smoke. When a local atmo- sphere becomes stagnant, smog pollution levels can create “killer fogs.” Three times in recent history these killer fogs have caused statistically significant in- creases in the death rate, particularly among those with respiratory problems. The first instance oc - curred in 1948 in Donora, Pennsylvania, when a stag- nated fog became progressively more contaminated with the smoky effluents from local steel mills. The second case occurred in 1952 in London when a stag- nant fog mixed with the smoke from thousands of coal-burning homes caused many with respiratory ail- ments to die. Finally, during Thanksgiving of 1966, New York City experienced an increased death rate because of choking smog. A second, completely different type of smog is “photochemical smog,” a noxious mixture of reactive chemicals created when sunlight catalyzes reactions of residual hydrocarbons and nitrogen oxides from automotive exhaust. The first occurrence of such was in the late 1940’s in Los Angeles, where the abundant sunlight and the dramatic increase ofvehicular traffic created ideal conditions for photochemical smog. This smog contains, among other things, powerful eye irritants, noisome odors, and dangerous reactive compounds. Although first observed in Los Angeles, photochemical smog later became prevalent in most other large cities. Chlorofluorocarbons When first synthesized in the 1930’s, chlorofluoro- carbon (CFC) was hailed as an ideal refrigerant Global Resources Air pollution and air pollution control • 23 Data from the U.S. Environmental Protection Agency,Source: National Emissions Inventory (NEI) Air Pollution Emissions Trend Data, 1970-2002. 119.5 36.9 14.9 4.8 0.2 Millions of People 12010080604020 Lead Ozone Particulate Matter (2.5-micron-diameter) Particulate Matter (10-micron-diameter) Sulfur Dioxide NAAQS (National Ambient Air Quality Standards).Note: People Living in Countries with Pollution Levels Higher than U.S. NAAQS, 2008 (Freon) because it was nontoxic, noncorrosive, non - flammable, and inexpensive to produce. Later, pres- surized CFCs were used as aerosol propellants and as the working fluid for air conditioners and refrig- erators. By 1970 scientists realized that the huge quan- tities of CFCs released into the atmosphere from aerosol cans and discarded refrigerant units were migrating to the stratosphere, where they were de- composed by highly energetic ultraviolet radiation from the Sun, releasing large quantities of ozone- destroying chlorine. The reduction ofozonewasmost pronounced over Antarctica, where an “ozone hole,” first detected in the early 1970’s, was increasing in size annually. In1978, pressured by environmentalists and consumerboycotts, the U.S. government banned aerosol cans and refrigeration units utilizingCFCpro- pellant, forcing the chemical industry to develop al- ternatives. By 1987 the depletion of the ozone layer had become so problematic that most industrial na- tions met in Montreal to ratify an international treaty calling for immediate reductions in all CFC use with a complete phase-out by the year 2000. By 2001 the Montreal Protocol had limited the damage to the ozone layer to about 10 percent of what it would have been had the agreement not been ratified. Air Pollution Control in the United States In the United States, the first attempts to control the smog or black smoke prevalent in industrial cities were the Clean Air Act of 1963 and the Motor Vehicle Pollution Act of 1965. The 1963 act was too weak to be effective; in 1967, the stronger Air Quality Act was en- acted. The Clean Air Act Amendments of 1970 man- dated national air quality standards set by the Envi- ronmental Protection Agency (EPA) to be met by 1975. Standards for six major air pollutants (sulfur oxides, nitrogen oxides, particulates, ozone, carbon monoxide, and lead)were legislated. When thepollu- tion concentration exceeded these limits, control de- vices were obligatory, regardless of the cost. Although most formsof air pollution were reduced after enactment of the Clean Air Act Amendments, mounting public concern over the continuing deteri- oration ofair quality inmajor cities resulted in several important revisions in 1990. New legislation man- dated that coal-burning power plants reduce sulfur oxide emissions by 9 million metric tonsperyearfrom 1980 levels by the year 2000. The revisions also re- quired that industry reduce several hundred carcino- genic airborne substances by up to 90 percent by the year 2000. Because of its smogproblem, California set even more stringent standards by legislating that 2 percent of all new vehicles must emit zero emissions by 1998, a rate that was to increase to 10 percent by 2003. In October, 2006, the EPA’s scientific advisers recommended that the allowable levels of surface ozone be substantially reduced, but industrial lobby- ing and the conservative political climate prevented any substantial change. During the decades following the Clean Air Act Amendments, particulate emissions decreased by 80 percent, carbon monoxide by 55 percent, hydrocar- bon emissions by 40 percent, sulfur oxides by 27 per- cent, and atmospheric lead by 98 percent. The partic- ulate emission reduction is attributed to control equipment installed on utility plant and industrial smokestacks, a decreased use of coal, and lessburning of solid wastes. Carbon monoxide and hydrocarbon emissions have decreased, despiteanincrease in auto- motive traffic, because of federal automotive emis- sion standards. The drop in sulfur oxides is directly attributable to a switch to low-sulfur coal and the re- moval of sulfur from the discharged gases at electric power plants. The drastic drop of lead compounds in the atmosphere resulted from the switch to unleaded gasoline during the 1970’s. During the first decade of the twenty-first century, concern aboutglobal warming causedbyCO 2 created a consensus that drastic action was needed to reduce this threat. Early in 2009, the EPA declared CO 2 an air 24 • Air pollution and air pollution control Global Resources Percentage Change in U.S. Emissions (millions of tons per year) 1980 vs. 2008 Carbon monoxide −56 Lead −99 Nitrogen oxides −40 Volatile organic compounds −47 Direct particulate matter (10-micron-diameter) −68 Direct particulate matter (2.5-micron-diameter) — Sulfur dioxide −56 Source: Data from U.S. Environmental Protection Agency, Air Quality Trends, 2009. pollutant, thus empowering the Clean Air Act to establish national emission standards for new automobiles and new coal-fired electric power plants, the two largest contributors to global warming emissions. Global Air Quality Control Air pollution, an ongoingproblem in in- dustrialized nations, has also become problematic in virtually all undeveloped countries undergoing rapid industrial- ization. The countries of the European Union have taken collective action be- cause pollution generated in one coun- try affects air quality in neighboring countries. Because road transportation is Europe’slargestairpolluter,beginning in the 1970’s motor vehicles manufac- tured on the Continent have had re- quired exhaust-emission controls. Fossil- fuel emissions from power plants and factories are also stringently regulated. In the United Kingdom, national air quality objectives were instituted in 2000 in association with an air qual- ity network to monitor levels of major pollutants invari- ous locations andadaily warning systemto indicate po- tentiallydangerousairpollutionlevels.Inthesummer of 2006, a directive on emission ceilings for cleaner air in Europe was passed by the European Parliament. The environmental crisis in the former Soviet re- publics of Eastern Europe is a direct result of the poli- cies pursued under the communist regime, when rapid industrialization ignored local conditions. Air pollution controls were deemedunnecessary because the biosphere was assumed to be self-purifying. With the advent of glasnost, a state committee on environ- mental protection was instituted in 1988; this became a state ministry in 1991 but was abolished nine years later. No significant change inecologicalconcerns oc- curred after the fall of the communist regime and the transition to capitalism.Becauseagencies responsible for environmental matters are either nonexistent or severely underfunded, internationally funded pollu- tion abatement projects are abandoned when the funds expire. The country with the greatest number of prema- ture deaths because of air pollution is India, where rapid industrialization and urbanization combined with unregulated vehicular emissions and uncon - trolled industrial effluents have exacerbated a preex- isting problem. Legislation to alleviate the crisis in cities such as New Delhi, one of the top-ten most pol- luted cities in the world, has been extremely difficult to implement. Auto emissions account for approxi- mately 70 percent of urban air pollution, and regula- tions required all public transportation vehicles in New Delhi to switch to compressed natural gas en- gines by April 1, 2001. However, the statute had to be rescinded when it removed about fifteen thousand taxis and ten thousand buses from service, creating commuter chaos and public riots. India’s high airpol- lution has not happened because of a lack of legisla- tion but becauseof insufficient enforcement at thelo- cal level. China’s growing economy has removed millions of people from poverty, to the detriment of the environ- ment. The increase of urban automotive traffic, the dependence on coal, and a weak environmental pro- tection system have left China with sixteen of the world’s twenty most polluted cities. Both urban and rural dwellers suffer from air pollution, which annu- ally causes approximately 400,000 premature deaths and 75 million asthma attacks. In 2005, to help allevi- ate the problem, the government proposed that strict fuel efficiency standards and emission controls be required on all vehicles. China’s excessive air pollu - Global Resources Air pollution and air pollution control • 25 In Bangladesh, workers in a brick field stand adjacent to a chimney emitting black smoke. (AP/Wide World Photos) tion is not contained within its borders. Unregulated airborne effluents from the numerous coal-burning plants reach Japan and become a major contributor to acid rain. In addition, sulfate-encrusted dust, car- bon particulates, andnitrates cross the Pacific Ocean, where they are responsible foralmost one-third ofthe polluted air over Los Angeles and San Francisco. Arguably, Japan is the Asian country that has taken air pollution abatement and control most seriously. Laws regulating the emission of sulfur dioxide and ni- trogen oxides are among the strictest in theworld,but polluted air from China keeps the rain acidic. The huge increase in automotivetraffic in recent decades is a major contributor to urban air pollution as well as se- vere congestion. Several stringent laws regulate auto- motive emissions in an attempt to control these re- lated problems. In addition, the Japanese environment agency promotes low-emission vehicles andcontinues to strengthen measures to reduce factory emissions. In June, 2001, the Japanese legislature passed a law strengthening controls on diesel vehicle emissions; two years later, diesel-powered commercial vehicles were banned from Tokyo if these limits were exceeded. Context More than three million premature deaths in the world occur annually because of air pollution, the greatest number of these occurring in India. In both developed and developing nations,airpollutionfrom the escalating number ofvehicles,aswell as consumer preference for larger, more powerful vehicles, con- tinues as a major challenge despite gains since the 1980’s. Controlling air pollution is not inexpensive. Pollution control devices increase costs to factories and to automobiles, costs that are passed to the con- sumer. Unless a radical change away from conspicu- ous consumption and the overreliance on fossil fuels occurs, air quality will not improve substantially. The issue of whether global warming is caused by humans may not be completely resolved, but strong measures to control carbon dioxide as wellas noxious gaseous and particulate air pollutants began during the last decades of the twentieth century. Because the preponderance of scientific evidence suggests that global warming is due to humanity’s excessive use of fossil fuels, it would seem prudent to curtail the disproportionate dependence on nonrenewable re- sources. When it was discovered that the ozone layer was being depleted by CFCs, the Montreal Protocol was ratified by most industrial nations. This precedent indicates that strong, effective action and interna - tional cooperation are possible when the threat tothe environment are grave enough. George R. Plitnik Further Reading Ayres, Jon, Robert Maynard, and Roy Richards, eds. Air Pollution and Health. London: Imperial College Press, 2006. Calhoun, Yael, ed. Air Quality. Philadelphia: Chelsea House, 2005. Gribbin, John. Hothouse Earth: The Greenhouse Effect and GAIA. New York: Grove Weidenfeld, 1990. Jacobson, Mark Z. Atmospheric Pollution: History, Sci- ence, and Regulation. New York: Cambridge Univer- sity Press, 2002. Metcalfe, Sarah, and Dick Derwent. Atmospheric Pollu- tion and Environmental Change. London: Hodder Arnold, 2005. Miller, G. Tyler, Jr. Living in the Environment: Principles, Connections, and Solutions. 15th ed. Pacific Grove, Calif.: Brooks/Cole, 2007. Seinfeld, John H., and Spyros N. Pandis. Atmospheric Chemistry and Physics: From Air Pollution to Climate Change. New York: John Wiley & Sons, 2006. Somerville, Richard C. J. The Forgiving Air:Understand- ing Environmental Change. 2d ed. Boston: American Meteorological Society, 2008. Vallero, Daniel. Fundamentals of Air Pollution. 4th ed. Burlington, Mass.: Academic Press, 2008. Web Sites Environment Canada Clean Air Online http://www.ec.gc.ca/cleanair-airpur/Home- WS8C3F7D55-1_En.htm U.S. Environmental Protection Agency Clean Air Act http://www.epa.gov/air/caa U.S. Environmental Protection Agency Air Pollution Effects http://www.epa.gov/ebtpages/ airairpollutioneffects.html See also: Acid precipitation; Atmosphere; Carbon; Clean Air Act; Electrical power; Environmental Pro- tection Agency; Greenhouse gases and global climate change; Internal combustion engine; Ozone layer and ozone hole debate. 26 • Air pollution and air pollution control Global Resources Alaska pipeline Categories: Historical events and movements; obtaining and using resources Date: Congress authorized construction in November, 1973; construction began April, 1974; pipeline completed in 1977 The planto construct a trans-Alaskan oil pipelinenet- work generated considerable controversy. After comple- tion, the pipeline, a triumph of engineering, helped lower U.S. dependency on imported oil during the 1980’s. Background The Naval Petroleum Reserve was created on the north slopeofAlaska in 1923, butfor two decades, the exploratory wells drilled there came up dry. More - over, the cost of commercial drilling in Alaska ap- peared prohibitive. From the 1930’s to the 1950’s, oil was cheap, and interest in Alaska’s unproven reserves plummeted. During the 1960’s, the increasing price of oil and the possibility of a decline in the security of oil sup- plied from abroad combined to revive interest in Alaska’s oil possibilities. The Atlantic Richfield Com- pany (later ARCO) obtained the majority of the gov- ernment leases granted for exploratory and develop- mental activity in Alaska. On December 26, 1967, in temperatures 30° Celsius belowzero, ARCO struck oil and discovered the largest oil field ever found in North America. Huge technological challenges had to be over- come, including obtaining the oil in volume in the subzero temperatures of Alaska’s north slope and Global Resources Alaska pipeline • 27 This portion of the Alaska pipeline was designed to trace the path of the Denali fault. (USGS) transporting itsafely to theport of Valdez in the south of Alaska for shipment by tankers to California. Con- struction of a mammoth,nearly 1,300-kilometer pipe- line seemed to be the only way to transport the oil across the frozen tundra. The political obstacles to transporting the oil proved even more challenging. Environmentalists feared that the pipelinewoulddo irrevocabledamage to Alaska’s ecological systems. The National Environ- mental Policy Act (NEPA), which was passed after the Santa Barbara oil spillof1969, gave environmentalists the leverage they needed to oppose the pipeline’s construction. When the Department of the Interior tried to satisfy the NEPA requirements by filing a slight eight-page environmental impact statement, the Friends of the Earth and the Environmental De- fense Fund obtained a court injunction on April 13, 1970, which halted construction of the pipeline until a definitive court ruling on compliance with NEPA could be obtained. Work on the pipeline was suspended for nearly four years as proponents and opponents battled in the bureaucracy andthe courts. Then came the Octo- ber, 1973, Yom Kippur War, the Arab oil embargo on Western countries assisting Israel, and the quadru- pling of the price of imported oil to nearly twelve dol- lars per barrel. A month later, on November 16, 1973, Congress relieved the Department of the Interior of further obligations under NEPA and approved the construction of a nearly ten-billion-dollar trans- Alaska pipelinefrom Prudhoe Bay to Valdez. In April, 1974, the monumental task of constructing apipeline that would notbeenvironmentallydisruptive began. Impact on Resource Use The pipelinewas completed in 1977 and within ayear was carrying one million barrels of oil per day to Valdez. By the early 1980’s, the amount being trans- ported had doubled, reducing the U.S. appetite for imported oil. The opening of the Alaska pipeline came too late to prevent a second oil crisis in 1979 from driving the price of imported oil to more than thirty-six dollars per barrel butnot too late to contrib- ute to the general decline in Western demand for Or- ganization of Petroleum Exporting Countries (OPEC) oil during the 1980’s. During that decade OPEC lost control over the production rates of member states and was unable to prevent the price of oil from plum - meting before restabilizing in the 1990’s at approxi - mately twenty dollars per barrel. In 2006, oil prices spiked again when the Department ofTransportation insisted the Alaska pipeline be examined after an oil spill that leaked nearly6,290barrels. Upon inspection conducted by British Petroleum (BP), the pipeline was found to have a high level ofcorrosion,forcingBP to replace nearly 26 kilometers of pipeline and caus- ing a temporary shutdown of service. Joseph R. Rudolph, Jr. See also: Energy economics; Energy politics; Exxon Valdez oil spill; Oil and natural gas drilling and wells; Oil and natural gas exploration; Organization of Pe- troleum Exporting Countries. Alloys Categories: Mineral and other nonliving resources; products from resources Alloys are solid combinations of metals or of metals and nonmetallic elementsthathave technologically de- sirable properties. The discoveries of various alloys have marked significant turning points in human history. Background Alloys are mixtures of metal—such as iron, coal, cop- per, tin, and lead—with other metals or with nonme- tallic elements developed to add desirable properties to those possessed by the metallic elements. These properties include strength, hardness, resistance to corrosion, and the ability to withstand high tempera- tures. The properties of alloys depend not only on their chemical composition but also on the way they have been prepared. Steel, a family of alloys based on the addition of carbon and other elements to iron, is perhaps the most familiar example in modern tech- nology, but alloys based on aluminum, cobalt, gold, nickel, mercury, titanium, and many other elements are also of great practical importance. In many cases the role they play in alloy formation is the determin- ing factor in the importance attached to these ele- ments as natural resources. The metals used in alloys must be extracted from theirores, a process that often leaves environmentally troublesomeby-productssuch as sulfur oxides. The manufacture of alloys generally requires sustained high temperatures, creating a de - mand for fossil fuels and raising concern about ther - mal pollution. 28 • Alloys Global Resources History Archaeologists and historians have named the stages of early civilization after the principal materials used for tools in each of them. Thus at various times in dif- ferent parts of the world, civilization progressed from the Stone Age to a Bronze Age, and then to an Iron Age. Bronze, a mixture of copper andtin, was the first alloy to receive extensive use. Bronze artifacts dated as early as 3500 b.c.e. have been found in both Asia Mi- nor andChina. The Hittites are believed to have been the first peoples, in about 1500 b.c.e., to have discov- ered how to extractmetallic iron from its ores. Thesu- perior strength of iron led to the replacement of bronze by iron in armor, weaponry, and knives. The iron used by early civilizations was undoubtedly an al- loy, though it was not understood as such. Steel, formed bythe addition ofcarbon to iron, wasmade in India by 1000 b.c.e. Brass, a mixture of copper and zinc, appears to have been known to the Romans. Modern Alloys Alloys are generally grouped into ferrous alloys, those containing iron, and nonferrous alloys. Bronze and brass remain among the mostcommonnonferrous al- loys. Bronze is used in numerous industrial applica- tions and as a durable material for sculptures. Brass is readily machined and widely used in hardware, elec- trical fixtures, and decorations. Aluminum, extracted from bauxite ore by high-temperature electrolysis, is alloyed with manganese, magnesium, or other ele- ments to produce a lightweight rigid material. Ferrous alloys include steels and cast iron. Cast irons are alloys of iron with 2 to 4 percent carbon and up to 3 percent silicon. Steels are alloys of iron that contain a smalleramountof carbon as wellas other el- ements. The manufacture of steel requires extremely high temperatures. Numerous forms of steel exist. Chromium steel has increased hardness and rust re- sistance. Stainless steel is a special form of chromium steel with admixtures of manganese, silicon, and nickel. Molybdenum, titanium, phosphorus, and sele- nium may also be added. Manganese is added to steel to increase strength and durability. Tungsten steels are stronger at high temperatures. Vanadium steel has greater elasticity and is suited to parts that must bend and regain their shape. Alloys of gold and silver are important in coinage and for decorative purposes. Gold is alloyed with sil - ver and copper forjewelry. Sterling silver is an alloy of silver with copper. Certain alloys are employed in dentistry and medi - cine. Throughout most of the twentieth century den- tists made liberal use of mercury amalgam, a mold- able mixture of mercury, silver, and other elements, as a filling material for dental caries (cavities). Concern about mercury toxicity led to areduction in use ofthis material. Orthopedic surgeons frequently use stain- less steel screws, pins, and rods to hold fractured bones in place so that they can heal properly. Alloys also play a role in a variety of orthopedic implants used to replace badly worn or damaged joints. Another important group of alloys is thoseusedfor permanent magnets. These include alnico, a combi- nation of aluminum, nickel, and cobalt. Other mag- netic materials include iron-nickel and iron-aluminum combinations. The rare earth elements also play a role in some magnetic materials. Superalloys are materials based on nickel, cobalt, or an iron-nickel mixture and contain carefully con- trolled amounts of trace elements designed to exhibit high strength at temperatures above 1,000° Celsius. These materials are used in jet engines, in heat ex- changers, and in chemical production plants. Impact of Alloys on Natural Resources The development andrefinement of alloy technology have had a dual effect on natural resource utilization. By making a larger variety of consumer goods avail- able, the development of new alloys has tended to ac- celerate the use of mineral ores and energy sources. However, the emergence of alloys that are lighter, more corrosion resistant, and amenable to recycling, as well as the replacement of some alloys by polymer- based materials and other alloys, slowedthe rate ofre- source use somewhat after its peak in the 1970’s. Donald R. Franceschetti Further Reading Askeland, Donald R., and Pradeep P. Phulé. The Sci- ence and Engineering of Materials. 5th ed. Toronto: Nelson, 2006. Campbell, F. C., ed. Elements of Metallurgy and Engi- neering Alloys. Materials Park, Ohio: ASM Interna- tional, 2008. Kranzberg, Melvin, and Cyril Stanley Smith. “Mate- rials in History and Society.” In The Materials Revolu- tion, edited by Tom Forester. Cambridge, Mass.: MIT Press, 1988. Plowden, David. Steel. New York: Viking Press, 1981. Raymond, Robert. Outofthe Fiery Furnace: The Impact of Global Resources Alloys • 29 . Air Act of 1 963 and the Motor Vehicle Pollution Act of 1 965 . The 1 963 act was too weak to be effective; in 1 967 , the stronger Air Quality Act was en- acted. The Clean Air Act Amendments of 1970. island Global Resources Agronomy • 21 of Madagascar in the late twentieth century. It is the role of agronomy to manage soil and crop resources as effectively as possible so that the twin goals of. the quadru- pling of the price of imported oil to nearly twelve dol- lars per barrel. A month later, on November 16, 1973, Congress relieved the Department of the Interior of further obligations