Encyclopedia of Global Resources part 108 docx

ter the 1970’s, when fuel costs increased and environ - mental concerns over pesticide use increased, brush control practices were reduced considerably. Modern environmental concerns include rangeland degradation from livestockgrazing, especiallyon riparian vegetation along streams, endangered animal and plant species. These issues have become controversial in the United States. Rangelands as Ecosystems Rangelands constitute natural ecosystems with nonliving environmental factors such as soil and climatic factors, primary producers (grasses, forbs, and shrubs), herbivores (livestock; big gameanimals such as deer, bison, pronghorn antelope; and many ro- dents and insects), carnivores and omnivores (coy- otes, bears,weasels, eagles, spiders,and cougars),and decomposers that break down organic matter into elements that can be utilized by plants. Plants convert carbon dioxideandwater intocomplex carbohydrates, fats, and proteins that can be utilized by animals feed- ing on the plants. Individual chemical elements are circulated throughout the various components. Many of these elements are present in the parent material of the soil (for example, phosphorus, magnesium, potassium, and sulfur). Nitrogen, on the other hand, is present in large amounts in the atmosphere but must be converted (fixed) into forms that can be utilized by plants before it can be cycled. When chemicals are taken up by plant roots from the soil solution, they are available to a wide group of herbivores from small microbes to large ungu- lates. Eventually nutrients are passed on to higher trophic groups (omnivores and carnivores). Both plant and animal litter is eventually broken down by decomposers—bacteria, fungi, and other small soil organisms—and returned to the soil or, in the case of nitrogen, given off to the atmosphere. Energy is fixed through the process of photosynthesis and transformed to forms useful for the plants themselves and animals that feed on the plants. How- ever, energy is degraded at each step along the way and cannot be used again. Energy is transferred but not cycled. Grazing animals on rangelands influence plants by removing living tissue, by trampling, and by altering competitive relationswith otherplants.Large grazing animals tend to compact the soil and reduce infiltration and increase surface runoff. Plants fur - nish all the nutrients obtained by herbivores and eventually by carnivores and omnivores as well. Rangeland Dynamics Rangelands vary considerably with time; they are not static. Scientists are gaining a better understanding of some factors related to rangeland change over time. Pollen records and, in the southwestern United States, packrat middens have been used to recon- struct past climate and vegetational changes. Some areas have become drier and others more mesic. For- mation and retreat of glaciers have influenced rangelands, climatic patterns, and soil development. A re- cent general trend in many rangelands of the world is an increase in woody plants at the expense of grasses. Many factors are probably responsible for theseshifts, but fire control, excessive livestock grazing, climatic shifts, introduction of exotic species, and the influence of native animals are likely causal agents. Rangelands are threatened byencroachment from crop agriculture as human populations increase. No- madic herders traditionally dealt with periodic drought conditions by moving to areas not impacted by drought. In modern society, with reductions of area availablefor livestock grazing and restrictions for political reasons,herders areoften forced to maintain higher livestock numbers to support their growing families and others directly dependent on livestock. Despite various kinds of disturbances and stresses on rangelands, these areas have supported many large grazing animalsand people for centuries. Theyare re- silient and will likely be sustained for many more centuries to come. Rex D. Pieper Further Reading Anella, Anthony, and John B. Wright. Saving the Ranch: Conservation Easement Design in the American West. Photographsby Edward Ranney. Washington, D.C.: Island Press, 2004. Heady, Harold F., and R. Dennis Child. Rangeland Ecology and Management. Boulder, Colo.: Westview Press, 1994. Holechek, Jerry L., Rex D. Pieper, and Carlton H. Herbel. Range Management: Principles and Practices. 5th ed.Upper Saddle River, N.J.:Pearson/Prentice Hall, 2004. Johnson, Barbara H., ed. Forging a West That Works— An Invitation to the Radical Center: Essays on Ranching, Conservation, and Science. Santa Fe, N.Mex.: Quivira Coalition, 2003. Miller, G. Tyler, Jr. Resource Conservation and Manage - ment. Belmont, Calif.: Wadsworth, 1990. 998 • Rangeland Global Resources Sayre, Nathan F. The New Ranch Handbook: A Guide to Restoring Western Rangelands. Santa Fe, N.Mex.: Quivira Coalition, 2001. White, Courtney. Revolution on the Range: The Rise of a New Ranch in the American West. Washington, D.C.: Island Press/Shearwater Books, 2008. See also: Conservation; Ecology; Farmland; Forests; Land management; Livestockand animal husbandry; Overgrazing; Public lands. Rare earth elements Category: Mineral and other nonliving resources Where Found Mixtures of the rare earth elements are present, but only insmall amounts,in mostrocks ofthe Earth. The rare earth elements are more concentrated in rocks of the continents than in those of the ocean basins. The minerals monazite, a phosphate mineral, and bastnäsite, a fluorine-carbonate mineral, form the main ores for the rare earth elements with lower atomic numbers. Xenotime, another phosphate mineral, is mined for its concentration of the rare earth elements with higher atomic numbers. The largest sources of rare earth elements are from bastnäsites mined in China and the United States. Monazite deposits are found in Australia, Brazil, Chile, India, Malaysia, South Africa, Sri Lanka, Thailand, and the United States. Primary Uses Mixtures of the rare earth elements are used for breaking down hydrocarbons in petroleum to form more gasoline, to remove impurities from iron and steel, as polishing materials, for carbon arcs, and in metallurgy. Pure rare earth elements are used as col- oring agents. Technical Definition The rare earth elements (abbreviated REE), or lanthanide elements, are a group of elements from atomic numbers 57 to 71. Their atomic weights range from 138.91 to 174.99. This large group of elements is grouped together because they have similar chemical properties. The names of the rare earth elements, from low to high atomic numbers, are lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dyspro- sium, holmium, erbium,thulium,ytterbium, andlute- tium. Inaddition, theelements scandiumand yttrium (atomic numbers 21 and 30 respectively) are some- times included with the rare earth elements because they have chemical properties similar to those of the rare earth elements. The density of the pure metals ranges from 5.23 to 9.84 grams per cubic centimeter. Melting points for the metals range from 798° to 1,663° Celsius. Description, Distribution, and Forms The rare earth elements, because of their similar chemical properties, do not occur as separate individual elements in minerals. Rather, they are frac- tionated in similar ways within or on the Earth. The rare earth elements are not normally soluble inwater, so they are not transported in solution by natural waters. The rare earth elements are widely distributed in the rocks of the world. The concentrations of some of the rare earth elements are as high as those of copper or zinc. For example, the dark, fine-grained rocks composing much of the ocean floor (called basalts) contain about 3 to 5 parts per million lanthanum, whereas igneous and sedimentary rocks on the continents typically contain 20 to 100 parts per millionlan- thanum. The rare earth elements are lowest in concentration in carbonate rocks such as limestone. History A mineral now called gadolinite was discovered by Jo- han Gadolin, who subsequently separated an “element” called yttria from gadolinite in 1796. Later it was discovered that yttria actually consisted of a concentration of the heavy rare earth elements. Another “element” called ceria was separatedin the early nineteenth century; ceriawas later discovered to consist of a concentration of the light rare earth elements. By the mid-nineteenth century, individual rare earth element oxides were separated from yttria and ceria by a series of chemical separations and identi- fied after analytical techniques such as the spectro- graph were developed. Obtaining Rare Earth Elements Monazite and the associated xenotime are mined from beach sands in Brazil, India, Australia, South Carolina, SouthAfrica, and Russia.Monazite isweakly Global Resources Rare earth elements • 999 magnetic and may be separated from the non-ore minerals by magnetic separation. Bastnäsite is mined in Africa, China, and the United States. It occurs in large amounts at Mountain Pass in California mixed with the non-ore minerals quartz, barite, and calcite. The ore is crushed, and bastnäsite is concentrated by flotation. The rare earth elements are furtherconcen- trated by heating and leaching with hydrochloric acid. Minor amounts of the rare earth elements are also produced as by-products from other ore processing, such as uranium production. Uses of Rare Earth Elements Rare earth elements have a large variety of end uses, in glass-polishing agents, ceramics, catalytic convert- ers, computer monitors (phosphors), lighting, radar, televisions, X-ray films, chemicals, petroleum-refining catalysts, pharmaceuticals, magnets, metallurgy, and laser and scintillator crystals. Pure europium mixed with yttrium oxides, for example, produces an intense red fluorescence, so the mixture is used in television screens. Pure lanthanum oxide isused to makequality glass forlenses. The rare earth elements are also used for X-ray screens, high-quality magnets, artificial diamonds, and super- alloys. Robert L. Cullers Further Reading Delfrey, Keith N., ed. Rare Earths: Research and Applica- tions. New York: Nova Science Publishers, 2008. Greenwood, N. N.,andA. Earnshaw. Chemistry of theEl- ements. 2d ed. Boston: Butterworth-Heinemann, 1997. Gschneidner, Karl A.,ed. Industrial Applicationsof Rare Earth Elements: Based on a Symposium Sponsored by the Division of Industrial and Engineering Chemistry at the Second Chemical Congress of the North American Conti- nent (180th ACS National Meeting), Las Vegas, Ne- vada, August25-26, 1981. Washington,D.C.: Ameri- can Chemical Society, 1981. Kogel, JessicaElzea,et al.,eds.“Rare Earth Elements.” Industrial Minerals and Rocks: Commodities, Markets, and Uses.7th ed. Littleton,Colo.: Societyfor Mining, Metallurgy, and Exploration, 2006. Krebs, Robert E. “Lanthanide Series (Rare-Earth Ele- ments): Period 6.” In The History and Use of Our Earth’s ChemicalElements: A Reference Guide. 2d ed. Il - lustrations by Rae Déjur. Westport, Conn.: Green - wood Press, 2006. Web Sites U.S. Geological Survey Rare Earth Elements: Critical Resources for High Technology http://pubs.usgs.gov/fs/2002/fs087-02 U.S. Geological Survey Rare Earths: Statistics and Information http://minerals.usgs.gov/minerals/pubs/ commodity/rare_earths See also: Alloys; Igneous processes, rocks, and mineral deposits; Magnetic materials; Metals and metallurgy. Reclamation Act Categories: Laws and conventions; government and resources Date: Passed by Congress June 17, 1902 The Reclamation Act marked the beginning of active federal involvementin thedevelopment ofirrigated agriculture in the western United States. Background The Reclamation Act, passed by Congress in 1902, established a comprehensive federal program of agricultural water development for the western United States. The Reclamation Act authorized the secretary of the interior to undertake construction of dams, reservoirs, and diversion facilities to provide irrigation water to farmers in all sixteen states west of, and including, the tier of states from North Dakota down to Oklahoma.These projects were to befunded from the newly created reclamation fund, which was to be financed from the sale of public lands in the sixteen states and revenues from sale of irrigation water. Consistent with a long tradition of nineteenth century federalpublic-lands policies that encouraged small-scale farming, the Reclamation Act restricted the sale of irrigation water to farms of less than 65 hectares. Provisions Passage of the Reclamation Act was the culmina - tion of a decade-long political struggle over how the arid regions of the western United States were to 1000 • Reclamation Act Global Resources be reclaimed. By the late nineteenth century, irriga - tion was taking hold throughout the West. In 1890, the U.S. Census of Agriculture counted more than 1.5 million irrigated hectares spread over fifty-four thousand farms in the sixteen western states. How- ever, increasing costs of water development, greater need for storage of surplus water, and the increasingly interstate character of water development all stimulated western demand for federal involvement in reclamation. This demand intensified in 1893 when economic depression struck, making it much more difficult for states and private entities to de- velop water on their own. However, enactment of federal reclamation was delayed by political resistance from many eastern quarters and by divisions within the West over the desirability of federal involvement. Resistance within the West was overcome when provisionswere inserted thatensured that reclamation benefitswould be spread throughout the West and that existing water rights would be respected. In addition, federal reclamation was given a strong boost after President Theodore Roosevelttook office, as Roosevelt was an active supporter of western irrigation. The Reclamation Act passed handily through a coalition of western interests and congressional Democrats. Impact on Resource Use Within a month of passage of the Reclamation Act, Secretary of the Interior Ethan Hitchcock had created the Reclamation Service (later the Bureau of Reclamation) and charged it with carrying out the federal reclamation program. The Reclamation Ser- vice quickly went to work, with Hitchcock approving five major projects within a year. However, as its work progressed, the Reclamation Service soon encoun- tered difficulties in securing payment from farmers, particularly during times of economic distress. This led Congress in 1914 to increase the time period over which payments were due from ten to twenty years. Subsequent congressional legislation passed in 1926 and 1939 made repayment terms increasingly favor- able to farmers. The result has been a federal reclamation program that has heavily subsidized western farmers, though this was not the intent of the original Reclamation Act. Mark Kanazawa See also: Bureau of Reclamation, U.S.; Department of the Interior, U.S.; Irrigation; Water. Recycling Categories: Environment, conservation, and resource management; pollution and waste disposal The debate over dumping trash versus recycling its re- usable components has existed since the beginning of technology. New technologies have made the issues different and more complex, but they are nevertheless es- sentially housekeeping issues affecting every material and product used in society. Recycling can save resources, reduce toxic wastes in the ecosystem, and save space in landfills. Background A number of factors led to the recycling programs initiated in the 1970’s and 1980’s. Throughout history, waste disposal schemes have generally assumed that there was infinite sky and ocean to dilute wastes until they became undetectably faint. Then rivers began to catch fire, mercury was discovered in tuna caught at sea, forests in Scandinavia suffered from sulfur dioxide coming from British smokestacks, and people in the fishing village of Minamata, Japan, were poisoned by a vinyl factory that was dumping wastes into their bay. Many such instances finally led to the realization that thenatural world was not aninfinite sinkand that humankind might be fouling its own nest. Hence, beginning in the 1970’s, ecology became a major political issue. A related concern was that fuels and certain key minerals might be exhausted in the near future because of the ever-expanding consumption of non- renewable resources. These fears were strongly pre- sented in 1970 in “The First Report to the Club of Rome,” published as The Limits to Growth, based on a computer projection of population,food production, industry, resources, and pollution. The “landfill crisis” in the United States began in the 1970’s when environmental regulations restricted open dumps, backyardburning, and burning in apartment-sized incinerators. Restricted burning cleared the air but increased the burden on dumps. Other new regulations required greater use of sanitary landfills, in which trash is covered daily. Because trash in sanitary landfills has less environmental dete - rioration from fires, rain, and vermin, it requires as much as three times the volume of old dumps. Global Resources Recycling • 1001 Waste Streams Wastes canbe defined ina number of ways. Municipal solid waste (MSW), or trash, is the most commonly considered object of recycling. MSW is an almost in- finitely varied mixture of newspapers, grass clippings, beverage containers, aerosol cans, old clothes, kitchen wastes, small appliances, and hundreds of other types of items. Calculations from the Environmental Pro- tection Agency for 2007 listed roughly 254 million metric tons of municipal solid waste in the United States—approximately 2 kilograms per person per day. However, the numbers are more complicated than that. They do not include construction and demoli- tion debris(about155 millionmetric tons) composed of bricks,wood,concrete, andfixtures takenwhenold structures are razed. They also do not include the liner and covering materials for the landfill. Finally, they do not include sewage sludge, composed of both food garbage that is ground up in garbage disposals and human wastes. With those additions, the average daily weight produced per person nearly doubles. Other complications in figuring the waste stream 1002 • Recycling Global Resources United States Environmental Protection Agency, 2007.Source: 23.7 Percentage Recovered 70605040302010 Yard trimmings Other nonferrous materials Aluminum Ferrous metals Glass Plastics Rubber and leather Other wastes 22.6 33.2 26.9 66.3 5.8 12.2 51.7 27.0 54.5 Paper and paperboard 42.8 2000 2007 33.8 21.8 69.3 14.7 64.1 31.9 6.8 Percentages of Recovered Municipal Solid Wastes, 2000 and 2007 come from good news. Automobiles and appliances are now rare in landfills because they are recycled for the metal. Beginning in the second half of the twentieth century, steel “mini-mills” allowed more profit- able recyclingof suchitemsbecause themini-mills are less susceptible to “poisoning” by metals other than iron. Corrugated paper boxes (cardboard) would be a much larger percentage of the waste stream than they are, but retailers smash, bale, and return large numbers to the manufacturers. There are other, much larger, waste streams than municipal waste, including manufacturing and sludges; agriculturalwastes,such ascorn cobsand manure; and mine tailings. However, municipal waste takes priority as far as recycling goes; one reason is that, if buried in landfills, some of these materials (paint, radioactive elements of smoke alarms, insecti- cide, nickel-cadmium batteries, and the mercury in fluorescent light tubes) could create toxic messes centuries in the future. Repurposing Waste Recycling, orreusing materialsfor otherpurposes, reduces trash, energy use, and theconsumption of mineral resources. For example, aluminum cans that are melted andmade into newcans donot goto a landfill; they require no aluminum ore and much less energy than smelting new aluminum. A society with a “total recycling” program could conceivably function with little mining of nonfuel minerals (assuming a neutral population growth). Recycling increased greatly beginning in the 1970’s, and governments have begun favoring recycled products over those made from virgin materials. In some European countries, manufacturers are held responsible for the eventual scrapping of their products, which results in designs favoring quick disassembly and recycling of standard materials. Technological Innovations Every waste stream is a potential resource stream. Many waste streams are already composed of liquids or smallparticles foreasier processing. Thusthere are myriad technologiesfor recycling and great prospects for improvement, depending on the money and ef- fort that a society is willing to expend. Many companies have profited from the “industrial ecology” of using waste streams from one area as resource streams for another. For instance, the ashes from burning coal have always been available as a raw material for making cement, but pilot projects to do so were onlystarted in the1980’s when environmental pressures increased. Likewise, manure can be spread back on fields or biologically digested to yield natural gas and concentrated fertilizer. The energy crisis of the 1970’s and 1980’s led to increased use of cogeneration, in which food-processing plants burn waste products such as corn cobs and shells from nuts for both process heat and generation of electricity. Even asphalt and concrete can be ground up and reused. Some of the most likely improvements to municipal waste recycling include automated sorting, electronic monitoring of the liquid trash in sewers, charg- ing for eventual disposal, and use of materials on-site. Automated sortinglowers laborcosts,allows sortingat any time, and allows a finer sorting. For instance, a manual trash “disassembly line” has stations for separating aluminum, iron, brass, all other metals, plastics, wood, and glass, but an automated facility can separate many types of plastics, metals, glass, and or - ganic matter. Separating out nonorganic materials al - Global Resources Recycling • 1003 Workers sort through recyclable materials at a waste management site in San Francisco, a city that uses innovative recycling techniques to sort paper, plastics, glass, concrete, wood, and metal. (Getty Images) lows processing the remaining material into some - thing usable and nontoxic. Piles of damp organic material naturally compost into soil through the ac- tion of bacteria. Hot diluted acid breaks the woody cellulose of organic materials into sugars that can be fermented into fuel alcohol. Using materials on-site includes composting of yard wastes and kitchen scraps. Just as cities run composting operations, gardeners have composted for centuries to fertilize their gardens. Meanwhile, trash collection agencies are spared the collection and landfill costs of burying dirt. Another method is plumbing houses so that wastewater from showers and hand washing (“gray water”) can be recycled for watering ornamental plants. Monitoring of sewers allows the use of an old recycling method, spreading processed sewage sludge on fields as fertilizer for nonfood crops. Unfortunately, sewage sludgecan beeasily tainted by industrial wastes, such as metalions or solvents. These wastes could poi- son the soil indefinitely. Until the early 1990’s there was no cost-effective way to monitor the sewers. Then cellular phones became widespread, anddevelopment began on computer-chip-sized sensors. Together these two technologies allow waste-management officals to monitor wastes in sewer lines in real-time so that ille- gal wastes can be detected immediately. The Economics of Recycling Recycling saves material, and it often reduces energy consumption. However, collection and processing use energy and require labor as well as storage areas for the materials beingrecycled. Successful recycling must balance those profits and costs. Historically, recycling was feasible and widely practiced because labor was cheap and materials were expensive. Rag pickers col- lected old cloth for making paper. Polite wealthy diners leftsomefood ontheir plates sothat itcould be given to the poor. Communist China provides a modern example that shows thedrawbacks of intensive recycling: During the period of revolutionary fervor that existed from the 1950’s through the 1970’s, one program involvedreturning andrepairing lightbulbs. Unfortunately, each worker in a light-bulb assembly factory averagedproduction of hundreds ofbulbs per hour, while a repair technician only fixed several. Such labor-intensive recycling cannot compete in the modern world. A second factor is that some materials favor recy - cling more than others. Glass containers are initially cheaper than aluminum ones, but glass is heavy (pos - sessing low value per unit weight) to recycle back to collection points;moreover, tiny amounts of thewrong color ruin the color in remelted batches, and glass shards are dangerous. Meanwhile, the primary raw material for new glass is as common as sand on the beach. Like aluminum, plastic has a high value in recycling because of light weight and great energy advantages. However, just as glass has many colors, plastics include many formulas. Mixing different kinds of plastics may degradethe performance of the recycled product. Worse, metals in inks on plastic containers may degrade performance or make the recycled plastic unsuitable for uses near food. Successful plastics recycling requires methods to sort or separate different kinds of plastics and, ideally, would include prohi- bitions against toxic inks. Paper box beverage containers with just one-stop recycling have several advantages over both glass and aluminum. They are initially cheaper. They are lighter and pack more product in a given storage volume, saving energy in transportation and storage. Finally, they can be crushed into a renewable fuel roughly equivalent to brown coal in heating value. (Once again, this is a low unit value, applicable only with automated sorting to remove metals that would make the ash toxic.) There are levels of recycling. Returnable bottles, simply washed and reused, represent the highest level. A lesser recycling level is remelting material to make new containers. Lesser yet, but still useful, is using glass andplastic as aggregate for paving. Lastly, simply burning the organic material can be used to produce energy, and it greatly reduces landfilling. E-Waste Electronic waste (or “e-waste”) has become an increasingly important part of the waste stream since the 1990’s. These wastes include consumer electron- ics such as computers, their accessories (mice, monitors, keyboards), cell phones, and televisions. The toxic contents of some of the components of e-waste require that they be recycled properly, by experts in the proper disposal and repurposing of hazardous wastes. Some of the components can be reused. For example, cell phones and televisions can be donated to prolong theirlives, and the materials (plastics,met - als, glass) can be retrieved and reused. On average, however, inthe United Statesonly about15 percentof 1004 • Recycling Global Resources these wastes are recycled annually, the rest finding their way to landfills. Even e-wastes that are conscien- tiously transported to hazardous waste centers can find their way to salvage yards, where their toxins can leak into groundwater. It is estimated that a large por- tion of e-waste resides in consumers’ closets and ga- rages, where it sits while owners are deciding how to rid themselves of it. Although some enterprising individuals have started businesses based on recycling these wastes,theproblem ofmountinge-waste contin- ues to grow. Social and Political Aspects Almost everyone wants sometrash to berecycled, and as cheaply as possible. The first responses to the environmental movement were additions to labels that cost little (“Dispose of this container properly!”) and did not produce significant results. Until container deposit taxes were instituted, it was feared that North America would be buried under empty aluminum cans. Likewise, other types of recycling can work only if there are financial incentives. These incentives might be like the “green dot” program in Europe, which holds manufacturers responsible for the ultimate disposal oftheproduct. Thisprogramhas ledcompanies to design for eventual disassembly. The previously mentioned waste deposit taxes repay people for re- turning sorted items. Trash taxes, rules, and limits on individuals have a limited value. If too harsh, they simply give people an incentive to rebel against them. Similarly, detailed sets of rules on how things should be done are probably counterproductive. Industrial ecology has worked better in Europe than inthe United Statesbecause industry could simply be ordered to reduce wastes. In the United States,certain materials are categorized as toxic wastes and treated under the Resource Conser- vation and Recovery Act of 1976 (Public Law 94-580), one of the most complex sets of regulations ever de- vised. Recycling of many of these materials is forbid- den, but the problem of how to reuse remains. For this reason, the Environmental Protection Agency’s Web site not only describes how to recycle or dispose of wastes but also urges conservation. Roger V. Carlson Further Reading Alexander, Judd H. In Defense of Garbage. Westport, Conn.: Praeger, 1993. Cothran, Helen, ed. Garbage and Recycling: Opposing Viewpoints. San Diego, Calif.: Greenhaven Press, 2003. Leverenz, Harold,George Tchobanoglous, andDavid B. Spencer. “Recycling.” In Handbook of Solid Waste Management, edited by Tchobanoglous and Frank Kreith. New York: McGraw-Hill, 2002. Lund, Herbert F., ed. The McGraw-Hill Recycling Hand- book. 2d ed. New York: McGraw-Hill, 2001. Porter, Richard C. The Economics ofWaste. Washington, D.C.: Resources for the Future, 2002. Rathje, William L., and Cullen Murphy. Rubbish! The Archaeology of Garbage. New York: HarperCollins, 1992. Reprint. Tucson: University ofArizona Press, 2001. Royte, Elizabeth. Garbage Land: On the Secret Trail of Trash. New York: Little, Brown, 2005. Strasser, Susan. Waste and Want: A Social History of Trash. New York: Metropolitan Books, 1999. Tierney, John. “Recycling Is Garbage.” The New York Times Magazine, June 20, 1996, p. 24. Web Site U.S. Environmental Protection Agency Recycling http://www.epa.gov/wastes/conserve/rrr/ recycle.htm See also: Aluminum; Cogeneration; Hazardous waste disposal; Incineration of wastes; Landfills; Paper; Superfund legislation and cleanup activities; Waste management and sewage disposal; Water supply sys- tems. Reforestation Category: Environment, conservation, and resource management The growth of new trees in an area that has been cleared of trees for commercial forestry or for agriculture is knownas reforestation. Reforestation can occur naturally or be initiated by people. Many areas of the eastern United States, such as the New England region, reforestednaturally asfarmland was abandoned and allowed to lie fallow for decades in the nineteenth and early twentieth centuries. Global Resources Reforestation • 1005 Background Some form of reforestation to replace trees removed for commercial purposes has been practiced in West- ern Europe since the late Middle Ages. English mon- archs, including Queen Elizabeth I, realized that forests were a vanishing resource and established plantations of oaks and other hardwoods to ensure a supply of ship timbers. Similarly, the kings of Sweden created a corps of royal foresters to plant trees and watch over existing woodlands. These early efforts at reforestation were inspired by the threatened disappearance of a valuable natural resource, but by the mid-nineteenth century it waswidely understood that the removal of forest cover contributes to soilerosion, water pollution, and the disappearance of many species of wildlife.Water falling onhillsides made barren by clear-cutting timberwashes awaytopsoil andcauses rivers to choke with sediment, killing fish and inter- fering with navigation. Without trees to slow the flow of water, rain can also run off slopes too quickly, caus- ing rivers to flood. Safeguarding Timber Resources After an area has been logged, both environmentalists and thecommercial forest industry advocate planting trees rather than waiting for natural regrowth, because the process of natural regeneration can be slow as well as unpredictable. In natural regeneration, the mixture of trees ina naturally reforested area may differ significantly from the forest that preceded it. For example, when nineteenth century loggers clear-cut the whitepine forests ofthe Great Lakes region, many logged-over tracts grew back primarily in mixed hardwoods. In addition, land that has been damaged by industrial pollution or agricultural practices may have lost the ability to support natural reforestation. In some regions of Africa,soils exposed byslash-and-burn agriculture often contain high levels of iron or aluminum oxide. Without a protective cover of vegetation, even under cultivation soil may undergo a process known as laterization and become rock-hard. Rather than un- dergoing natural reforestation, such abandoned farmland ismore likelytoremain barren ofalmostall plant life formany years. Inareas where industrial pollution exists, such as former mining districts, native trees may not be able to tolerate the toxins in the soil; in such cases more tolerant species must be introduced. Reforestation differs from tree farming in that the goal of reforestation is not merely to provide wood - lands for future harvest. Although tree farming is a type of reforestation in that trees are planted to replace those that have been removed, in tree farming generally only one species of tree is planted with the explicit intention that it be harvested later. The trees are seen first as a crop and only incidentally as wildlife habitat or a means of erosion control. As foresters have become more knowledgeable about the complex interactions within forest ecosystems, however, tree-farming methods have begun to change. Rather than monocropping (planting only one variety of tree) on plantations, the commercial forest industry has begun planting mixed stands. Trees once considered undesirable weed trees because they possessed no perceived commercial valueare nowrecognized as nitrogen fixers necessary for the healthy growth of other species. In addition to providing woodlands for possible use in commercial forestry, reforestation includes goals such as wildlife habitat restoration and the reversal of environmental degradation. Ecological and Environmental Aspects Scientists did not clearly establish the vital role that trees, particularly those in tropical rain forests, play in removing carbon dioxide from the atmosphere through the process of photosynthesis until the mid- twentieth century. Carbon dioxide is a greenhouse gas: It helps trap heat in the Earth’s atmosphere. As forests disappear, the risk of global warming—caused in part by an increase in the amount of carbon dioxide in the atmosphere—becomes greater. For many years, soil conservationists advocated reforestation as a way to counteract the ecological damage caused by erosion. Beginning in the 1980’s, scientists and environmental activists concerned about global warming joined foresters and soil conservationists in urging that for every tree removed anywhere, whether to clear land for development or to harvest timber, re- placement trees be planted. As the area covered by tropical rain forests shrinks in size, the threat of irre- versible damage to the global environment becomes greater. In 1988, American Forests, an industry group, began the Global ReLeaf program to encourage reforestation efforts in an attempt to combat global warming. Bythe end of2006, this program had planted 25 million trees. Reforestation Programs In addition to supporting reforestation efforts by gov - ernment agencies, corporations, and environmental 1006 • Reforestation Global Resources organizations, Global ReLeaf and similar programs encourage individualsto practicereforestation intheir own neighborhoods. Trees serve as a natural climate control, helping to moderate extremes in tempera- ture and wind. Trees in a well-landscaped yard can reduce homeowners’energy costsby providing shadein the summer and serving as a windbreak during the winter. Global ReLeaf is only one of many programs that support reforestation efforts. Arbor Day, an annual day devoted to planting trees for the beautification of towns or the forestation of empty tracts of land, was established in the United States in 1872. The holiday originated in Nebraska, a prairie statethat seemed unnaturally barren to home- steaders used to eastern woodlands, and initially it emphasized planting trees where none had existed before. Arbor Day is observed in public schools to ed- ucate young people about the importance of forest preservation, and in some states it is a legal holiday. Organizations such asthe Arbor Day Foundation provide saplings (young trees) to schools and other organizations for planting in their own neighborhoods. Nancy Farm Männikkö Further Reading Berger, John J. Forests Forever: Their Ecology, Restoration, and Protection. Chicago: Center for American Places at Columbia College, 2008. Cherrington, Mark. Degradation of the Land.New York: Chelsea House, 1992. Gradwohl, Judith, and Russell Greenberg. Saving the Tropical Forests. Illustrated by Lois Sloan. Washing- ton, D.C.: Island Press, 1988. Küchli, Christian. Forests of Hope: Stories of Regeneration. Stony Creek, Conn.: New Society, 1997. Lamb, David,andDon Gilmour. Rehabilitationand Res- toration of Degraded Forests. Gland, Switzerland: IUCN, 2003. Lipkis, Andy, and Katie Lipkis. The Simple Act of Planting a Tree: A Citizen Forester’s Guide to Healing Your Neighborhood, Your City, and Your World. Los An- geles: J.P. Tarcher, 1990. Mansourian, Stephanie, Daniel Vallauri, and Nigel Dudley. Forest Restoration in Landscapes: Beyond Planting Trees. New York: Springer, 2005. Rietbergen-McCracken, Jennifer, Stewart Maginnis, and Alastair Sarre, eds. The Forest Landscape Restora- tion Handbook. London: Earthscan, 2007. Weiner, Michael A. Plant a Tree: A Working Guide to Regreening America. New York: Macmillan, 1975. Web Sites American Forests Global Releaf http://www.americanforests.org/global_releaf Arbor Day Foundation Replanting Our National Forests http://www.arborday.org/replanting See also: Clear-cutting; Deforestation; Forest management; Forests; Maathai, Wangari; Rain forests; Slash-and-burn agriculture; Timber industry. Refrigeration. See Canning and refrigeration of food Remote sensing Categories: Obtaining and using resources; scientific disciplines The use of technology to acquire images and data about distant objects—including Earth—has ex- panded humans’ ability to understand the location, availability, and nature of resources on Earth. Background Remote sensing is the use of technology to extract information from objects or areas distant from the ob- server. It is the act of gathering information about a subject of interest without being in contact with the subject. This technology often collectsenergy beyond the sensitivityofhuman eyesand ears, utilizingthe en- tire range of energy of the electromagnetic spectrum, particles, or fields. Remote-sensing technology is a successful tool for the discovery, inventory, and management of resources, both natural and human-made. These techniques makepossible the collectionof data beyond the range of human senses. Moreover, the large-scale perspective remote sensing affords accel- erates our ability to map and identify change over time. Several areas in the sciences utilize remote-sensing techniques. Astronomy has perhaps the longest his - tory of gathering information from a distance, but there areother fieldsthat doso, suchas geophysicsus - Global Resources Remote sensing • 1007 . and Recovery Act of 1976 (Public Law 94-580), one of the most complex sets of regulations ever de- vised. Recycling of many of these materials is forbid- den, but the problem of how to reuse remains volume of old dumps. Global Resources Recycling • 1001 Waste Streams Wastes canbe defined ina number of ways. Municipal solid waste (MSW), or trash, is the most commonly considered object of recycling The toxic contents of some of the components of e-waste require that they be recycled properly, by experts in the proper disposal and repurposing of hazardous wastes. Some of the components can