Among European countries, one of the leaders in the fight against pollution is Sweden. In Stockholm, I lunched with Tage Erlander, Sweden's recently retired Prime Minister, who heads the planning committee for the International Pollution Control Conference to be held in the Swedish capital in 1972.
"When Rachel Carson's book Silent Spring was published here," he said, "it made quite an impact. About that time, too, we looked around to discover that our environment was deteriorating. But you don't just make a law saying there shall be no pollution. To get it under control, we needed public support."
Education was the key. A Swedish student starts learning ecology in primary grades, and he'll be exposed to the subject all the way through high school. In college he can cross normal academic linesfor instance, he can major in biology and also in the legal aspects of pollution control. In 1968 adult courses were set up all over Sweden, financed by folksam, a large insurance cooperative. More than 150,000 adults took the courses in that first yearin a country of eight million.
Hans Palmstierna, secretary of the government's advisory committee on environment, explained the ultimate goal. "Our targets are the people at local government levels," he said. "Before a community agrees to let a new factory come to town, we want its people to consider more than just the short-range economic gains. Will the new factory create environmental hazards? In our public-education courses, we teach adults to ask just such unpleasant question."
"Recycling is one good answer to the pollution problem," Mr. Palmstierna told me. "Our natural resources, like everyone else's, are limited. It doesn't make sense to dig them up, use them once, and then throw them into the environment as pollutants. We want to use them over and over."
Remember one of Aesop's Fablesthe story of the feckless grasshopper who frittered his summer away with no thought of barren months ahead? This has been a planet of grasshoppers.
But no longer. Anxious to mend our ways, we laymen are listening earnestly to a range of experts. The result, too often, is confusion. We're unsure of the prioritiesis cleaner air more vital than cleaner water? What can an individual do to help? Must he give up his air conditioner and his car?
I make no claim of expertisebut I have had the rare opportunity of interviewing experts in many countries. Here is the gist of what I have learned:
Virtually every scientist I listened toand they numbered in the dozensemphasized that mankind must control population growth. They forecast widespread famine if population soars unchecked. Plagues, toofor in the megalopolitan sprawl of the future there will no longer be sparsely settled buffer zones around cities to curb epidemics.
What are the priorities? Most ecologists answered something like this: Clean up the most threatened areas first. Work to unsnarl the fragmented, overlapping responsibility on national, state, and local levels. Focus research on finding environmental answersthere is so much yet to be learned.
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Be realistic about immediate goals. At least for now, settle for making a river clean enough to serve its particular purpose. Later, it can be made clean enough to drink.
Get practical, enforceable pollution laws passedstandardized ones that will apply to both sides of a river, for instance, when it flows between two states.
Before using a new chemical, explore for side effects. And when a new product is developed, plan for its ultimate disposal. Work toward recycling; one factory's industrial waste can be another plant's raw material.
And make each individual aware of the problemsand his role in solving them.
Source: Young, Gordon. Pollution, Threat to Mans Only Home. National Geographic, December 1970.
Microsoft Encarta Encyclopedia 2002. 1993-2001 Microsoft Corporation. All rights reserved.
Pollution
| I | INTRODUCTION |
Pollution, contamination of Earths environment with materials that interfere with human health, the quality of life, or the natural functioning of ecosystems (living organisms and their physical surroundings). Although some environmental pollution is a result of natural causes such as volcanic eruptions, most is caused by human activities.
There are two main categories of polluting materials, or pollutants. Biodegradable pollutants are materials, such as sewage, that rapidly decompose by natural processes. These pollutants become a problem when added to the environment faster than they can decompose (see Sewage Disposal). Nondegradablepollutants are materials that either do not decompose or decompose slowly in the natural environment. Once contamination occurs, it is difficult or impossible to remove these pollutants from the environment.
Nondegradable compounds such as dichlorodiphenyltrichloroethane (DDT), dioxins, polychlorinated biphenyls (PCBs), and radioactive materials can reach dangerous levels of accumulation as they are passed up the food chain into the bodies of progressively larger animals. For example, molecules of toxic compounds may collect on the surface of aquatic plants without doing much damage to the plants. A small fish that grazes on these plants accumulates a high concentration of the toxin. Larger fish or other carnivores that eat the small fish will accumulate even greater, and possibly life-threatening, concentrations of the compound. This process is known as bioaccumulation.
| II | IMPACTS OF POLLUTION |
Because humans are at the top of the food chain, they are particularly vulnerable to the effects of nondegradable pollutants. This was clearly illustrated in the 1950s and 1960s when residents living near Minamata Bay, Japan, developed nervous disorders, tremors, and paralysis in a mysterious epidemic. More than 400 people died before authorities discovered that a local industry had released mercury into Minamata Bay. This highly toxic element accumulated in the bodies of local fish and eventually in the bodies of people who consumed the fish. More recently research has revealed that many chemical pollutants, such as DDT and PCBs, mimic sex hormones and interfere with the human bodys reproductive and developmental functions. These substances are known as endocrine disrupters. See Occupational and Environmental Diseases.
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Pollution also has a dramatic effect on natural resources. Ecosystems such as forests, wetlands, coral reefs, and rivers perform many important services for Earths environment. They enhance water and air quality, provide habitat for plants and animals, and provide food and medicines. Any or all of these ecosystem functions may be impaired or destroyed by pollution. Moreover, because of the complex relationships among the many types of organisms and ecosystems, environmental contamination may have far-reaching consequences that are not immediately obvious or that are difficult to predict. For instance, scientists can only speculate on some of the potential impacts of the depletion of the ozone layer, the protective layer in the atmosphere that shields Earth from the Suns harmful ultraviolet rays.
Another major effect of pollution is the tremendous cost of pollution cleanup and prevention. The global effort to control emissions of carbon dioxide, a gas produced from the combustion of fossil fuels such as coal or oil, or of other organic materials like wood, is one such example. The cost of maintaining annual national carbon dioxide emissions at 1990 levels is estimated to be 2 percent of the gross domestic product for developed countries. Expenditures to reduce pollution in the United States in 1993 totaled $109 billion: $105.4 billion on reduction, $1.9 billion on regulation, and $1.7 billion on research and development. Twenty-nine percent of the total cost went toward air pollution, 36 percent to water pollution, and 36 percent to solid waste management.
In addition to its effects on the economy, health, and natural resources, pollution has social implications. Research has shown that low-income populations and minorities do not receive the same protection from environmental contamination as do higher-income communities. Toxic waste incinerators, chemical plants, and solid waste dumps are often located in low-income communities because of a lack of organized, informed community involvement in municipal decision-making processes.
| III | TYPES OF POLLUTION |
Pollution exists in many forms and affects many different aspects of Earths environment. Point-source pollution comes from specific, localized, and identifiable sources, such as sewage pipelines or industrial smokestacks. Nonpoint-source pollution comes from dispersed or uncontained sources, such as contaminated water runoff from urban areas or automobile emissions.
The effects of these pollutants may be immediate or delayed. Primary effects of pollution occur immediately after contamination occurs, such as the death of marine plants and wildlife after an oil spill at sea. Secondary effects may be delayed or may persist in the environment into the future, perhaps going unnoticed for many years. DDT, a nondegradable compound, seldom poisons birds immediately, but gradually accumulates in their bodies. Birds with high concentrations of this pesticide lay thin-shelled eggs that fail to hatch or produce deformed offspring. These secondary effects, publicized by Rachel Carson in her 1962 book, Silent Spring, threatened the survival of species such as the bald eagle and peregrine falcon, and aroused public concern over the hidden effects of nondegradable chemical compounds.
| A | Air Pollution |
Human contamination of Earths atmosphere can take many forms and has existed since humans first began to use fire for agriculture, heating, and cooking. During the Industrial Revolution of the 18th and 19th centuries, however, air pollution became a major problem. As early as 1661 British author and founding member of the British Royal Society John Evelyn reported of London in his treatise Fumifugium, the weary Traveller, at many Miles distance, sooner smells, than sees the City to which he repairs. This is that pernicious Smoake which fullyes all her Glory, superinducing a sooty Crust or Furr upon all that it lights.
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Urban air pollution is commonly known as smog. The dark London smog that Evelyn wrote of is generally a smoky mixture of carbon monoxide and organic compounds from incomplete combustion (burning) of fossil fuels such as coal, and sulfur dioxide from impurities in the fuels. As the smog ages and reacts with oxygen, organic and sulfuric acids condense as droplets, increasing the haze. Smog developed into a major health hazard by the 20th century. In 1948, 19 people died and thousands were sickened by smog in the small U.S. steel-mill town of Donora, Pennsylvania. In 1952, about 4,000 Londoners died of its effects.
A second type of smog,photochemical smog, began reducing air quality over large cities like Los Angeles in the 1930s. This smog is caused by combustion in car, truck, and airplane engines, which produce nitrogen oxides and release hydrocarbons from unburned fuels. Sunlight causes the nitrogen oxides and hydrocarbons to combine and turn oxygen into ozone, a chemical agent that attacks rubber, injures plants, and irritates lungs. The hydrocarbons are oxidized into materials that condense and form a visible, pungent haze.
Eventually most pollutants are washed out of the air by rain, snow, fog, or mist, but only after traveling large distances, sometimes across continents. As pollutants build up in the atmosphere, sulfur and nitrogen oxides are converted into acids that mix with rain. This acid rain falls in lakes and on forests, where it can lead to the death of fish and plants, and damage entire ecosystems. Eventually the contaminated lakes and forests may become lifeless. Regions that are downwind of heavily industrialized areas, such as Europe and the eastern United States and Canada, are the hardest hit by acid rain. Acid rain can also affect human health and man-made objects; it is slowly dissolving historic stone statues and building facades in London, Athens, and Rome.
One of the greatest challenges caused by air pollution is global warming, an increase in Earths temperature due to the buildup of certain atmospheric gases such as carbon dioxide. With the heavy use of fossil fuels in the 20th century, atmospheric concentrations of carbon dioxide have risen dramatically. Carbon dioxide and other gases, known as greenhouse gases, reduce the escape of heat from the planet without blocking radiation coming from the Sun. Because of this greenhouse effect, average global temperatures are expected to rise 1.4 to 5.8 Celsius degrees (2.5 to 10.4 Fahrenheit degrees) by the year 2100. Although this trend appears to be a small change, the increase would make the Earth warmer than it has been in the last 125,000 years, possibly changing climate patterns, affecting crop production, disrupting wildlife distributions, and raising the sea level.
Air pollution can also damage the upper atmospheric region known as the stratosphere. Excessive production of chlorine-containing compounds such as chlorofluorocarbons (CFCs) (compounds formerly used in refrigerators, air conditioners, and in the manufacture of polystyrene products) has depleted the stratospheric ozone layer, creating a hole above Antarctica that lasts for several weeks each year. As a result, exposure to the Suns harmful rays has damaged aquatic and terrestrial wildlife and threatens human health in high-latitude regions of the northern and southern hemispheres.
| B | Water Pollution |
The demand for fresh water rises continuously as the worlds population grows. From 1940 to 1990 withdrawals of fresh water from rivers, lakes, reservoirs, and other sources increased fourfold. Of the water consumed in the United States in 1995, 39 percent was used for irrigation, 39 percent was used for electric power generation, and 12 percent was used for other utilities; industry and mining used 7 percent, and the rest was used for agricultural livestock and commercial purposes.
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Sewage, industrial wastes, and agricultural chemicals such as fertilizers and pesticides are the main causes of water pollution. The U.S. Environmental Protection Agency (EPA) reports that about 37 percent of the countrys lakes and estuaries, and 36 percent of its rivers, are too polluted for basic uses such as fishing or swimming during all or part of the year. In developing nations, more than 95 percent of urban sewage is discharged untreated into rivers and bays, creating a major human health hazard.
Water runoff, a nonpoint source of pollution, carries fertilizing chemicals such as phosphates and nitrates from agricultural fields and yards into lakes, streams, and rivers. These combine with the phosphates and nitrates from sewage to speed the growth of algae, a type of plantlike organism. The water body may then become choked with decaying algae, which severely depletes the oxygen supply. This process, called eutrophication, can cause the death of fish and other aquatic life. Agricultural runoff may be to blame for the growth of a toxic form of algae called Pfiesteria piscicida, which was responsible for killing large amounts of fish in bodies of water from the Delaware Bay to the Gulf of Mexico in the late 1990s. Runoff also carries toxic pesticides and urban and industrial wastes into lakes and streams.
Erosion, the wearing away of topsoil by wind and rain, also contributes to water pollution. Soil and silt (a fine sediment) washed from logged hillsides, plowed fields, or construction sites, can clog waterways and kill aquatic vegetation. Even small amounts of silt can eliminate desirable fish species. For example, when logging removes the protective plant cover from hillsides, rain may wash soil and silt into streams, covering the gravel beds that trout or salmon use for spawning.
The marine fisheries supported by ocean ecosystems are an essential source of protein, particularly for people in developing countries. Yet pollution in coastal bays, estuaries, and wetlands threatens fish stocks already depleted by overfishing. In 1989, 260,000 barrels of oil was spilled from the oil tanker Exxon Valdez into Alaskas Prince William Sound, a pristine and rich fishing ground. In 1999 there were 8,539 reported spills in and around U.S. waters, involving 4.4 billion liters (1.2 billion gallons) of oil.
| C | Soil Pollution |
Soil is a mixture of mineral, plant, and animal materials that forms during a long process that may take thousands of years. It is necessary for most plant growth and is essential for all agricultural production. Soil pollution is a buildup of toxic chemical compounds, salts, pathogens (disease-causing organisms), or radioactive materials that can affect plant and animal life.
Unhealthy soil management methods have seriously degraded soil quality, caused soil pollution, and enhanced erosion. Treating the soil with chemical fertilizers, pesticides, and fungicides interferes with the natural processes occurring within the soil and destroys useful organisms such as bacteria, fungi, and other microorganisms. For instance, strawberry farmers in California fumigate the soil with methyl bromide to destroy organisms that may harm young strawberry plants. This process indiscriminately kills even beneficial microorganisms and leaves the soil sterile and dependent upon fertilizer to support plant growth. This results in heavy fertilizer use and increases polluted runoff into lakes and streams.
Improper irrigation practices in areas with poorly drained soil may result in salt deposits that inhibit plant growth and may lead to crop failure. In 2000 bc, the ancient Sumerian cities of the southern Tigris-Euphrates Valley in Mesopotamia depended on thriving agriculture. By 1500 bc, these cities had collapsed largely because of crop failure due to high soil salinity. The same soil pollution problem exists today in the Indus Valley in Pakistan, the Nile Valley in Egypt, and the Imperial Valley in California.
| D | Solid Waste |
Solid wastes are unwanted solid materials such as garbage, paper, plastics and other synthetic materials, metals, and wood. Billions of tons of solid waste are thrown out annually. The United States alone produces about 200 million metric tons of municipal solid waste each year (see Solid Waste Disposal). A typical American generates an average of 2 kg (4 lb) of solid waste each day. Cities in economically developed countries produce far more solid waste per capita than those in developing countries. Moreover, waste from developed countries typically contains a high percentage of synthetic materials that take longer to decompose than the primarily biodegradable waste materials of developing countries.
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Areas where wastes are buried, called landfills, are the cheapest and most common disposal method for solid wastes worldwide. But landfills quickly become overfilled and may contaminate air, soil, and water. Incineration, or burning, of waste reduces the volume of solid waste but produces dense ashen wastes (some of which become airborne) that often contain dangerous concentrations of hazardous materials such as heavy metals and toxic compounds. Composting, using natural biological processes to speed the decomposition of organic wastes, is an effective strategy for dealing with organic garbage and produces a material that can be used as a natural fertilizer. Recycling, extracting and reusing certain waste materials, has become an important part of municipal solid waste strategies in developed countries. According to the EPA, more than one-fourth of the municipal solid waste produced in the United States is now recycled or composted. Recycling also plays a significant, informal role in solid waste management for many Asian countries, such as India, where organized waste-pickers comb streets and dumps for items such as plastics, which they use or resell.
Expanding recycling programs worldwide can help reduce solid waste pollution, but the key to solving severe solid waste problems lies in reducing the amount of waste generated. Waste prevention, or source reduction, such as altering the way products are designed or manufactured to make them easier to reuse, reduces the high costs associated with environmental pollution.
| E | Hazardous Waste |
Hazardous wastes are solid, liquid, or gas wastes that may be deadly or harmful to people or the environment and tend to be persistent or nondegradable in nature. Such wastes include toxic chemicals and flammable or radioactive substances, including industrial wastes from chemical plants or nuclear reactors, agricultural wastes such as pesticides and fertilizers, medical wastes, and household hazardous wastes such as toxic paints and solvents.
About 400 million metric tons of hazardous wastes are generated each year. The United States alone produces about 250 million metric tons70 percent from the chemical industry. The use, storage, transportation, and disposal of these substances pose serious environmental and health risks. Even brief exposure to some of these materials can cause cancer, birth defects, nervous system disorders, and death. Large-scale releases of hazardous materials may cause thousands of deaths and contaminate air, water, and soil for many years. The worlds worst nuclear reactor accident took place near Chernobyl, Ukraine, in 1986 (see Chernobyl Accident). The accident killed at least 31 people, forced the evacuation and relocation of more than 200,000 more, and sent a plume of radioactive material into the atmosphere that contaminated areas as far away as Norway and the United Kingdom.
Until the Minamata Bay contamination was discovered in Japan in the 1960s and 1970s, most hazardous wastes were legally dumped in solid waste landfills, buried, or dumped into lakes, rivers, and oceans. Legal regulations now restrict how such materials may be used or disposed, but such laws are difficult to enforce and often contested by industry. It is not uncommon for industrial firms in developed countries to pay poorer countries to accept shipments of solid and hazardous wastes, a practice that has become known as the waste trade. Moreover, cleaning up the careless dumping of the mid-20th century is costing billions of dollars and progressing very slowly, if at all. The United States has an estimated 217,000 hazardous waste dumps that need immediate action. Cleaning them up could take more than 30 years and cost $187 billion.
Hazardous wastes of particular concern are the radioactive wastes from the nuclear power and weapons industries. To date there is no safe method for permanent disposal of old fuel elements from nuclear reactors. Most are kept in storage facilities at the original reactor sites where they were generated. With the end of the Cold War, nuclear warheads that are decommissioned, or no longer in use, also pose storage and disposal problems.
| F | Noise Pollution |
Unwanted sound, or noise, such as that produced by airplanes, traffic, or industrial machinery, is considered a form of pollution. Noise pollution is at its worst in densely populated areas. It can cause hearing loss, stress, high blood pressure, sleep loss, distraction, and lost productivity.
Sounds are produced by objects that vibrate at a rate that the ear can detect. This rate is called frequency and is measured in hertz, or vibrations per second. Most humans can hear sounds between 20 and 20,000 hertz, while dogs can hear high-pitched sounds up to 50,000 hertz. While high-frequency sounds tend to be more hazardous and more annoying to hearing than low-frequency sounds, most noise pollution damage is related to theintensity of the sound, or the amount of energy it has. Measured in decibels, noise intensity can range from zero, the quietest sound the human ear can detect, to over 160 decibels. Conversation takes place at around 40 decibels, a subway train is about 80 decibels, and a rock concert is from 80 to 100 decibels. The intensity of a nearby jet taking off is about 110 decibels. The threshold for pain, tissue damage, and potential hearing loss in humans is 120 decibels. Long-lasting, high-intensity sounds are the most damaging to hearing and produce the most stress in humans.
Solutions to noise pollution include adding insulation and sound-proofing to doors, walls, and ceilings; using ear protection, particularly in industrial working areas; planting vegetation to absorb and screen out noise pollution; and zoning urban areas to maintain a separation between residential areas and zones of excessive noise.
| IV | HISTORY |
Much of what we know of ancient civilizations comes from the wastes they left behind. Refuse such as animal skeletons and implements from stone age cave dwellings in Europe, China, and the Middle East helps reveal hunting techniques, diet, clothing, tool usage, and the use of fire for cooking. Prehistoric refuse heaps, or middens, discovered by archaeologists in coastal areas of North America reveal information about the shellfish diet and eating habits of Native Americans who lived more than 10,000 years ago.
As humans developed new technologies, the magnitude and severity of pollution increased. Many historians speculate that the extensive use of lead plumbing for drinking water in Rome caused chronic lead poisoning in those who could afford such plumbing. The mining and smelting of ores that accompanied the transition from the Stone Age to the Metal Age resulted in piles of mining wastes that spread potentially toxic elements such as mercury, copper, lead, and nickel throughout the environment.
Evidence of pollution during the early Industrial Revolution is widespread. Samples of hair from historical figures such as Newton and Napoleon show the presence of toxic elements such as antimony and mercury. By the 1800s, certain trades were associated with characteristic occupational diseases: Chimney sweeps contracted cancer of the scrotum (the external sac of skin enclosing the testes, or reproductive glands) from hydrocarbons in chimney soot; hatters became disoriented, or mad, from nerve-destroying mercury salts used to treat felt fabric; and bootblacks suffered liver damage from boot polish solvents.
During the 20th century, pollution evolved from a mainly localized problem to one of global consequences in which pollutants not only persisted in the environment, but changed atmospheric and climatic conditions. The Minamata Bay disaster was the first major indication that humans would need to pay more attention to their waste products and waste disposal practices, in particular, hazardous waste disposal. In the years that followed, many more instances of neglect or carelessness resulted in dangerous levels of contamination. In 1976 an explosion at a chemical factory in Seveso, Italy, released clouds of toxic dioxin into the area, exposing hundreds of residents and killing thousands of animals that ate exposed food. In 1978 it was discovered that the Love Canal housing development in New York State was built on a former chemical waste dump. The development was declared uninhabitable. The worlds worst industrial accident occurred in Bhopal, India, in 1984. A deadly gas leaked from an American chemical plant, killing more than 3,800 people and injuring more than 200,000.
The 1986 Chernobyl nuclear reactor accident demonstrated the dangerous contamination effects of large, uncontained disasters. In an unprecedented action, pollution was used as a military tactic in 1991 during the conflict in the Persian Gulf. The Iraqi military intentionally released as much as 1 billion liters (336 million gallons) of crude oil into the Persian Gulf and set fire to more than 700 oil wells, sending thick, black smoke into the atmosphere over the Middle East.
| V | CONTROLLING POLLUTION |
Because of the many environmental tragedies of the mid-20th century, many nations instituted comprehensive regulations designed to repair the past damage of uncontrolled pollution and prevent future environmental contamination. In the United States, the Clean Air Act (1970) and its amendments significantly reduced certain types of air pollution, such as sulfur dioxide emissions. The Clean Water Act (1977) and Safe Drinking Water Act (1974) regulated pollution discharges and set water quality standards. The Toxic Substances Control Act (1976) and the Resource Conservation and Recovery Act (1976) provided for the testing and control of toxic and hazardous wastes. In 1980 Congress passed the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), also known as Superfund, to provide funds to clean up the most severely contaminated hazardous waste sites. These and several other federal and state laws helped limit uncontrolled pollution, but progress has been slow and many severe contamination problems remain due to lack of funds for cleanup and enforcement.
International agreements have also played a role in reducing global pollution. The Montréal Protocol on Substances that Deplete the Ozone Layer (1987) set international target dates for reducing the manufacture and emissions of the chemicals, such as CFCs, known to deplete the ozone layer. The Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal (1989) serves as a framework for the international regulation of hazardous waste transport and disposal.
Since 1992 representatives from more than 160 nations have met regularly to discuss methods to reduce greenhouse gas emissions. In 1997 the Kyōto Protocol was devised, calling for industrialized countries to reduce their gas emissions by 2012 to an average 5 percent below 1990 levels. At the end of 2000 the Kyōto Protocol had not yet been ratified; negotiators were still working to find consensus on the rules, methods, and penalties that should be used to enforce the treaty.
Regulations and legislation have led to considerable progress in cleaning up air and water pollution in developed countries. Vehicles in the 1990s emit fewer nitrogen oxides than those in the 1970s did; power plants now burn low-sulfur fuels; industrial stacks have scrubbers to reduce emissions; and lead has been removed from gasoline. Developing countries, however, continue to struggle with pollution control because they lack clean technologies and desperately need to improve economic strength, often at the cost of environmental quality. The problem is compounded by developing countries attracting foreign investment and industry by offering cheaper labor, cheaper raw materials, and fewer environmental restrictions. The maquiladoras, assembly plants along the Mexican side of the Mexico-U.S. border, provide jobs and industry for Mexico but are generally owned by non-Mexican corporations attracted to the cheap labor and lack of pollution regulation. As a result, this border region, including the Río Grande, is one of the most heavily polluted zones in North America. To avoid ecological disaster and increased poverty, developing countries will require aid and technology from outside nations and corporations, community participation in development initiatives, and strong environmental regulations.
Nongovernmental citizen groups have formed at the local, national, and international level to combat pollution problems worldwide. Many of these organizations provide information and support for people or organizations traditionally not involved in the decision-making process. The Pesticide Action Network provides technical information about the effects of pesticides on farmworkers. The Citizens Clearinghouse for Hazardous Waste, established by veterans of the Love Canal controversy, provides support for communities targeted for hazardous waste installations. A well-organized, grassroots, environmental justice movement has arisen to advocate equitable environmental protections. Greenpeace is an activist organization that focuses international attention on industries and governments known to contaminate land, sea, or atmosphere with toxic or solid wastes. Friends of the Earth International is a federation of international organizations that fight environmental pollution around the world.
Contributed By:
Paul Engelking
Microsoft Encarta Encyclopedia 2002. 1993-2001 Microsoft Corporation. All rights reserved.
Thermal Pollution
| I | INTRODUCTION |
Thermal Pollution, harmful increase in water temperature in streams, rivers, lakes, or occasionally, coastal ocean waters. Thermal pollution is caused by either dumping hot water from factories and power plants or removing trees and vegetation that shade streams, permitting sunlight to raise the temperature of these waters. Like other forms of water pollution, thermal pollution is widespread, affecting many lakes and vast numbers of streams and rivers in the United States and other parts of the world. A temperature increase as small as 1 or 2 Celsius degrees (about 2 to 4 Fahrenheit degrees) can kill native fish, shellfish, and plants, or drive them out in favor of other species, often with undesirable effects.
| II | MAJOR SOURCES |
The major sources of thermal pollution are electric power plants and industrial factories. In most electric power plants, heat is produced when coal, oil, or natural gas is burned or nuclear fuels undergo fission to release huge amounts of energy. This heat turns water to steam, which in turn spins turbines to produce electricity. After doing its work, the spent steam must be cooled and condensed back into water. To condense the steam, cool water is brought into the plant and circulated next to the hot steam. In this process, the water used for cooling warms 5 to 10 Celsius degrees (9 to 18 Fahrenheit degrees), after which it may be dumped back into the lake, river, or ocean from which it came. Similarly, factories contribute to thermal pollution when they dump water used to cool their machinery.
The second type of thermal pollution is much more widespread. Streams and small lakes are naturally kept cool by trees and other tall plants that block sunlight. People often remove this shading vegetation in order to harvest the wood in the trees, to make room for crops, or to construct buildings, roads, and other structures. Left unshaded, the water warms by as much as 10 Celsius degrees (18 Fahrenheit degrees). In a similar manner, grazing sheep and cattle can strip streamsides of low vegetation, including young trees. Even the removal of vegetation far away from a stream or lake can contribute to thermal pollution by speeding up the erosion of soil into the water, making it muddy. Muddy water absorbs more energy from the sun than clear water does, resulting in further heating. Finally, water running off of artificial surfaces, such as streets, parking lots, and roofs, is warmer than water running off vegetated land and, thus, contributes to thermal pollution.
| III | IMPACTS |
All plant and animal species that live in water are adapted to temperatures within a certain range. When water in an area warms more than they can tolerate, species that cannot move, such as rooted plants and shellfish, will die. Species that can move, such as fish, will leave the area in search of cooler conditions, and they will die if they can not find them. Typically, other species, often less desirable, will move into the area to fill the vacancy.
In general, cold waters are better habitat for plants and animals than warm ones because cold waters contain more dissolved oxygen. Many freshwater fish species that are valued for sport and food, especially trout and salmon, do poorly in warm water. Some organisms do thrive in warm water, often with undesirable effects. Algae and other plants grow more rapidly in warm water than in cold, but they also die more rapidly; the bacteria that decompose their dead tissue use up oxygen, further reducing the amount available for animals. The dead and decaying algae make the water look, taste, and smell unpleasant (see Eutrophication).
| IV | CONTROLS |
Thermal pollution from power plants and factories is relatively easy to control. Instead of discharging heated water into lakes and streams, power plants and factories can pass the heated water through cooling towers or cooling ponds, where evaporation cools the water before it is discharged. Alternatively, power plants can be designed or refitted to be more efficient and to produce less waste heat in the first place. In a process called cogeneration, the excess heat energy from generating electricity can be used in another manufacturing process that needs such energy. Where homes or other buildings are located near industrial plants, waste hot water can be used for heatingan arrangement often found in Scandinavian towns and cities, and proposed for use in China.
In the United States, the problem of industrial thermal pollution was first addressed in 1970, when Congress gave the Atomic Energy Commission authority to regulate thermal pollution from nuclear power plants. In 1972, the comprehensive Clean Water Act instructed the Environmental Protection Agency to issue regulations to clean up all hot water discharges from all power plants, nuclear or conventional. Since then, thermal pollution from power plants has not been a major issue in the United States.
To prevent thermal pollution due to devegetation, the prescription is simple: do not devegetate. Landowners can leave strips of trees and vegetation along streams and shorelines. Grazing livestock can be kept away from streamsides by fencing. All efforts to control erosion also have the effect of keeping water clearer and, thus, cooler.
As a practical matter, however, thermal pollution from devegetation is quite hard to control because it is caused by the cumulative effect of many peoples actions, most of which are individually minor. Regulations focus on a few of the most important threats. Grazing management plans, for instance, are intended to counter thermal pollution and other problems on lands owned by the federal government. In the United States, regulations governing logging on both public and private lands supposedly protect streamsides, though enforcement is often lax. Elsewhere, streamside protection is largely up to private landowners, encouraged and aided by such advisory organizations as the federal Natural Resources Conservation Service and cooperative Resource Conservation Districts.
Contributed By:
John Hart
Microsoft Encarta Encyclopedia 2002. 1993-2001 Microsoft Corporation. All rights reserved.
Noise Pollution
| I | INTRODUCTION |
Noise Pollution or Sound Pollution, exposure of people or animals to levels of sound that are annoying, stressful, or damaging to the ears. Although loud and frightening sounds are part of nature, only in recent centuries has much of the world become urban, industrial, and chronically noisy.
Sound intensity is measured in units called decibels. The decibel scale is logarithmic and climbs steeply: An increase of about three decibels is a doubling of sound volume. In the wilderness, a typical sound level would be 35 decibels. Speech runs 65 to 70 decibels; heavy traffic generates 90 decibels. By 140 decibels, sound becomes painful to the human ear, but ill effects, including hearing loss, set in at much lower levels.
Most noise pollution comes from machines, especially automobiles, trucks, and aircraft. Construction equipment, farm machines, and the din of machinery inside factories can be dangerously loud. Some home appliances, shop tools, lawnmowers, and leaf blowers can also be noisy, as are guns, firecrackers, and some toys. Even music, when played at very high volume, particularly through personal headphones, is as damaging to the ears as a roaring chain saw.
Even the oceans are increasingly noisy. The engines of ships, especially large vessels and supertankers, produce a lot of sound, and traffic is increasing. Offshore oil exploration and drilling are also noisy. And more recently, very loud, low-frequency sonar signals are being sent through the seas to detect submarines and to gain information about water temperatures and global warming.
| II | IMPACTS |
The most significant health problem caused by noise pollution is hearing loss (see Deafness). Any noise appreciably louder than talking can damage the delicate hair cells in the cochlea, the structure in the inner ear that converts sound waves into auditory nerve signals. The initial damage to the cochlea may be temporary, but with repeated exposure, the damage becomes permanent. Loud noise deafens quicklyextremely loud sounds, such as gunshots at close range, can cause immediate hearing loss. But even sound levels of only 85 decibels will cause some hearing loss after prolonged exposure. Ten million Americans have some hearing loss due partly or wholly to exposure to loud sounds, and 20 million are at risk. In addition to deafness, many people with damaged ears are afflicted with tinnitus, or ringing in the ears.
Most hearing loss occurs in workplaces, where workers may be unable to avoid unhealthy noise, and where exposure may continue for years. Factory workers, construction workers, farmers, military personnel, police officers, firefighters, and musicians all have reason to be concerned about their occupational exposure to noise.
Even at levels below those that cause hearing loss, noise pollution produces problems. Noise makes conversation difficult, interferes with some kinds of work, and disturbs sleep. As a source of stress, it can promote high blood pressure and other cardiovascular problems, as well as nervous disorders. According to the National Institutes of Health, 65 million Americans are exposed to noise levels that can hamper their work or disrupt their sleep, and 25 million risk health problems due to noise.
Noise also puts stress on domestic animals and wildlife. In remote areas, helicopters and military aircraft often frighten animals. Aircraft noise in Alaska, for example, has been shown to reduce the survival rate of caribou calves. There is concern that increasing noise levels in the oceans may confuse the natural sonar that whales use to navigate, communicate, and locate food.
| III | CONTROLS |
Noise pollution is not a necessary price to pay for living in an industrial society. Much can be done to reduce the severity of the problem. For example, vehicles and other machines can be built to produce less noise. Four-cycle engines can replace much noisier two-cycle engines in such products as lawnmowers, motorboats, and jet skis. Labels that indicate the noise levels of appliances and tools can help consumers avoid noisy products and choose quieter alternatives.
Even after noise is generated, steps can be taken to reduce human exposure to it. At homes or in offices, insulation of walls and double-glazing of windows can muffle sound from traffic, neighbors, and other sources from the outside world. Sound walls along highways can shield nearby neighborhoods from traffic noise. Individuals should protect themselves with earplugs or mufflike ear protectors, particularly when noise levels exceed 85 decibels.
In the industrialized nations, governments have laws and policies to counter noise pollution. In the United States, at least six federal agencies are involved in controlling noise pollution. Since 1969 the Federal Aviation Administration (FAA) has monitored and controlled noise from airplanes. The agency requires that new aircraft meet specified noise standards and that old ones be retrofitted or retired. Local airport authorities, with FAA approval, reduce the impacts of noise pollution by routing flights over water or unpopulated areas on takeoff and landing, and by limiting traffic at night. The FAA also encourages airports and local governments to take steps on the ground, such as constructing sound barriers, insulating buildings, and restricting residential development in noisy areas. In extreme cases, airports have relocated people living under flight paths.
The Occupational Safety and Health Administration (OSHA) is charged with reducing noise in workplaces. Under OSHA regulations, no exposure above 115 decibels is permitted, exposure up to 115 decibels is limited to 15 minutes for an 8-hour shift, and average noise levels above 85 decibels are regulated. OSHA requires employers to measure noise levels, to muffle extremely noisy equipment, to provide ear-protection gear if necessary, and to offer regular hearing tests to workers who are regularly exposed to high sound levels. The Bureau of Mine Safety has comparable rules to protect miners. The Department of Housing and Urban Development and the Veterans Administration require noise-proofing in dwellings whose mortgages they finance. The Department of Defense even has noise standards for certain military situations.
In 1972 Congress passed a Noise Control Act establishing an Office of Noise Abatement and Control in the Environmental Protection Agency. The office conducted research, coordinated the work of other agencies, and directly set noise standards for trucks, motorcycles, air compressors, truck-mounted garbage compactors, and railroads. More standards would have followed, but in 1981 Congress cut off funding for this effort.
Some state and many local governments work to reduce noise pollution. State and local building codes include noise insulation requirements, and land-use planning is used to keep noise sources away from housing and offices. Local ordinances can ban the use of some equipment, such as leaf blowers, or limit use to certain times of day.
In the last 30 years, the United States and other countries have expended considerable efforts to control noise pollution. Most vehicles and many other noise producers are quieter than they used to be. On the other hand, there are more noise-making machines than ever, operating more of the time. In the United States, most of the rules governing noise pollution were established at least two decades ago, and critics are calling for new, stronger measures, as well as for better enforcement of the old ones. What is true of most other kinds of pollution is also true of noise: Our best efforts against it tend merely to keep matters from getting dramatically worse.
Contributed By:
John Hart
Microsoft Encarta Encyclopedia 2002. 1993-2001 Microsoft Corporation. All rights reserved.
Environment
| I | INTRODUCTION |
Environment, all of the external factors affecting an organism. These factors may be other living organisms (biotic factors) or nonliving variables (abiotic factors), such as water, soil, climate, light, and oxygen. All interacting biotic and abiotic factors together make up an ecosystem.
Organisms and their environment constantly interact, and both are changed by this interaction. Additionally, environmental factors, singly or in combination, ultimately limit the size that any population may attain. This limit, a populations carrying capacity, is usually reached because needed resources are in short supply. Occasionally, carrying capacity may be dictated by the direct actions of other species, as when predators limit the number of their prey in a specific area.
Like all other living beings, humans have clearly changed their environment, but they have done so generally on a grander scale than have other species. Some of these changessuch as the destruction of the worlds tropical rain forests to create grazing land for cattle or the drying up of almost three-quarters of the Aral Sea, once the worlds fourth-largest freshwater lake, for irrigation purposeshave led to altered climate patterns, which in turn have changed the distribution of species of animals and plants.
Scientists are working to understand the long-term consequences that human actions have on ecosystems, while environmentalistsprofessionals in various fields, as well as concerned citizens in the United States and other countriesare struggling to lessen the impact of human activity on the natural world.
| II | UNDERSTANDING THE ENVIRONMENT |
The science of ecology is the study of the interactions that determine the abundance and distribution of organisms. In other words, ecology attempts to explain why individuals live where they do and why their populations are the sizes they are.
No population, human or otherwise, can grow indefinitely; eventually, some biotic or abiotic variable will begin to limit population growth. This basic ecological principle was first established in 1840 by German chemist Justus von Liebig and has been called the Law of the Minimum. From a human standpoint, this means that all of the worlds physical resources are in finite supply.
Ecologists also have discovered that all species in an ecosystem interact with one another, either directly or indirectly. A classic ecological experiment illustrates this point very well. American ecologist Robert Paine, working in the rocky intertidal region of the Pacific coast, found stable invertebrate communities dominated by 15 species of animals, including starfish, mussels, limpets, barnacles, and chitons. When Paine removed all of the starfish from the area, the community collapsed, and eventually only 8 invertebrate species were common. Although it was not obvious in the undisturbed regions, the starfish were preying heavily on one of the mussel species and keeping its numbers down. With the starfish removed, the population of this mussel increased, and the mussel was able to outcompete many other species of invertebrates. Thus, the loss of one species, the starfish, indirectly led to the loss of an additional six species and a transformation of the community.
Typically, because the species that coexist in natural communities have evolved together for many generations, they have established a balance, and their populations remain relatively stable. Occasionally, when humans introduce a non-native species to an ecosystem, dramatic disruptions occur, often because the natural predators of the introduced species are not present. For example, early sailors routinely introduced goats to isolated oceanic islands, intending for the goats to roam freely and serve as a source of meat when the sailors later came ashore. Free from all natural predators, the goats thrived and, in the process, overgrazed many of the islands. With a change in plant composition, many of the native animal species were driven to extinction. A simple action, the introduction of goats to an island, yielded many changes in the island ecosystem, demonstrating that all members of a community are closely interconnected.
In the 1970s the British scientist James Lovelock formulated the Gaia hypothesis, which has attracted many followers. According to this theory, named after the Greek goddess of the earth, the planet behaves like a single living organism. Lovelock postulated that the earth, like many organisms, can regulate its temperature, dispose of its wastes, and fight off disease. Although the Gaia hypothesis serves as a convenient metaphor for the interconnections among living beings, it does not have any particular scientific merit.
From a scientific viewpoint, the earth is not a single living organism, but it can be viewed as a single integrated system. The National Aeronautics and Space Administration (NASA), using its expertise in planetary and space sciences, is collaborating with other U.S. governmental agencies in the use of artificial satellites to study global change. NASAs undertaking, begun in 1991, is called Mission to Planet Earth. This project is part of an international effort linking numerous satellites into a single Earth Observing System (EOS). EOS is designed to increase knowledge of the interactions taking place among the atmosphere, land, and oceans; to assess the impact of natural and human events on the planet; and to provide the data that permit sound environmental policy decisions to be made.
| III | HISTORY OF ENVIRONMENTALISM |
The modern American environmental movement is rooted in a 19th-century New England philosophical movement called transcendentalism, of which the poet and essayist Ralph Waldo Emerson and the naturalist and author Henry David Thoreau were leaders. In their writings, both expressed a reverence for the natural world, believing that humans and nature shared a divine spirit. Emerson asserted that nature was eternal and, much like the Gaia followers of the present day, contended that it was capable of recovering from mistreatment at the hands of humans. Thoreau, more protective and pessimistic, has been quoted as saying, Thank God, men cannot yet fly and lay waste the sky as well as the earth.
Although Emerson and Thoreau wrote eloquently about the value of nature and its spiritual importance to humans, neither of them undertook a systematic analysis of the effects that humans could have on their environment. That task was left for George Perkins Marsh, who published Man and Nature; or, Physical Geography as Modified by Human Action in 1864. This important book was the first to demonstrate that human activity could cause dramatic and irreversible damage to the earth. Marsh explained how agricultural practices had led to deforestation, loss of wetlands, desertification (the process of land becoming desert), species extinction, and changes in weather patterns.
Protection of federal lands defined the tenure of U.S. President Theodore Roosevelt, and during his years in office, from 1901 to 1909, he greatly expanded both the national forest and national park systems and created a system of national wildlife refuges. Roosevelt appointed forester Gifford Pinchot as head of the U.S. Forest Service, and together they molded American conservation on two major premises. They recognized that even the vast natural resources of the United States were not limitless and thus had to be managed carefully, and they believed that those resources should be used for the betterment of the American people. Roosevelt, thinking broadly about resources, claimed that one of the most valuable natural assets was the American people themselves, and he argued that the protection of human health was a central and valid focus for the conservation movement.
Roosevelt also was a friend of Scottish-American naturalist and essayist John Muir, founder of the Sierra Club. Muirs philosophical approach to the environment was very different from Pinchots: Muir valued nature for its own sake and argued forcefully to protect species and preserve wilderness, whereas Pinchot was much more concerned with the use of natural resources to serve human needs. Their perspectives fully diverged in the debate over Californias Hetch Hetchy Valley, often considered a twin to the Yosemite Valley, also in California. Pinchot wanted to dam the Tuolumne River and flood the valley to provide water and electricity to San Francisco, while Muir thought the destruction of such a natural wonder an abomination. Roosevelt sided with Pinchot and the dam was authorized in 1913.
When Franklin D. Roosevelt assumed the U.S. presidency in 1933, he continued and expanded on the conservation efforts begun earlier in the century during the administration of his second cousin. Not only did he expand national parks and national forests, but, in response to the twin challenges of massive unemployment in the Great Depression and environmental havoc wreaked by the Dust Bowl conditions in the Midwest, he created the Civilian Conservation Corps to replant forests and improve recreational opportunities on public land and the Soil Conservation Service to protect valuable topsoil.
In 1962 in her book Silent Spring, American biologist Rachel Carson warned of the grave dangers posed by the indiscriminate use of dichlorodiphenyltrichloroethane (DDT) and related pesticides. The title suggested a time when birds, their populations greatly reduced by pesticides, could no longer be heard singing in the spring. Carson, by arguing that humans as well as wildlife were at risk, issued a call to action. A combination of solid science, a reverence for nature as strong as that of the transcendentalists, and a wonderfully poetic style moved people to a new level of environmental awareness and activism.
On April 22, 1970, the first Earth Day, approximately 20 million Americans gathered at various sites across the country to protest corporate and governmental abuse of the environment. Earth Day, the events leading up to it, and its aftermath transformed American culture. Environmental awareness became much more commonplace, and numerous grassroots environmental organizations were established to work for political change, including the Environmental Defense Fund in 1967, Friends of the Earth in 1968, Greenpeace in 1970, the Natural Resources Defense Council in 1970, and the Sierra Club Legal Defense Fund in 1971.
| IV | LEGISLATION AND LITIGATION |
The strong environmental sentiments that led to Earth Day yielded dramatic changes in American legislation and reflected an expanded set of priorities. In 1964 the Congress of the United States passed the Wilderness Act in an attempt to set aside, in the words of the act, an area where earth and its community of life are untrammeled by man; the lands designated as wilderness areas were to be affected primarily by nature. In 1968 Congress adopted the Wild and Scenic Rivers Act to ensure that at least some of the scenic and recreational value of the countrys rivers was preserved in the face of a growing number of dams and riverside development.
In 1970 the Environmental Protection Agency (EPA) was established, and attention began to shift toward pollution control and the establishment of national environmental quality standards. The EPA was responsible for the environmental well-being of the country as defined through numerous specific pieces of legislation. One of these, the Clean Air Act of 1970, became the model for future measures. The act established national air-quality standards, gave states the responsibility for developing and enforcing plans to use these standards, and set up compliance schedules. Additionally, the act made federal funding available to states to assist in their efforts. The National Environmental Protection Act (NEPA), also enacted in 1970, required an environmental assessment of all federally funded projects.
The Occupational Safety and Health Administration (OSHA) was formed in 1970 as well, although it was placed under the control of the Department of Labor rather than the EPA. Reflecting Theodore Roosevelts belief that human health was a natural resource worthy of protection, OSHAs mission was to assure so far as possible every working man and woman in the Nation safe and healthful working conditions.
In 1972 Congress passed the Clean Water Act, designed to do for the nations water supply what the Clean Air Act accomplished for the atmosphere. The Endangered Species Act was passed the following year and has been described by the Supreme Court of the United States as the most comprehensive legislation for the preservation of endangered species ever enacted by any nation. The most important aspect of the legislation is its reliance on scientific rather than economic data.
The Resource Conservation and Recovery Act (RCRA) was adopted in 1976 with the twin goals of protecting human health and the environment and conserving valuable natural resources. Through this act, the federal government took a more active role in controlling solid and hazardous waste, as well as in promoting recycling. Despite the good intentions of RCRA, numerous hazardous waste sites were created throughout the country. To combat the dangers posed by these sites, Congress passed the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980. Known as Superfund, the act created a $15 billion fund of public money, to be increased by taxes on polluting industries. As huge as this fund is, it is inadequate to deal with the thousands of hazardous sites in need of cleanup. The vast majority of these sites occur on federal military reservations. Of the 35,000 sites screened since the passage of CERCLA in 1980, the EPA has chosen or is considering 1295 sites for its National Priorities List and estimates that 3000 sites eventually could be given this status.
The body of federal environmental legislation has been under increasing attack since the election of Ronald Reagan as president in 1980. Conservatives have argued that too much public money is being spent on the environment and that the federal government should play a much-reduced role in environmental regulation. In addition, some people believe that most restrictions on the use of private property are forbidden by the Fifth Amendment to the Constitution of the United States, which prohibits the taking of property without just compensation. When environmental laws limit use, the argument goes, property values decline and the government has taken or reduced the worth of private holdings. The U.S. Supreme Court has agreed with this reasoning and ruled that some environmental protection laws have placed unfair burdens on property owners. As each piece of environmental legislation is modified or comes before Congress for reauthorization, battles are fought between those who believe industry and development are being unnecessarily stifled and those who contend that the environment is being irreparably damaged.
Environmental advocacy groups have regularly taken to the courts in defense of the environment. Suits have been filed against the federal government in the hope of compelling its various agencies to enforce congressionally mandated acts. Additionally, advocacy groups have sued corporations directly for failing to follow various environmental laws.
| V | A GLOBAL APPROACH |
The environmental concerns growing in the United States during the late 1960s and early 1970s increased internationally as well. Perhaps the biggest impetus for d
