2 The Balance of the Environment The balance of the environment can be upset by the way in which humans obtain and use natural resources. If humans use renewable natural resources faster than they can be replaced, the balance will be upset. If we damage one resource in the process of obtaining or using another resource, the balance will be upset.
3 PollutionPollution is the release into the environment of substances that change the environment for the worse. Most pollution is the result of human activities.
4 The Trail of PollutionIn order to make a can of soda, the aluminum must be removed from the ground. Digging scars the land. Chemicals used in the factory to produce aluminum become waste that is discarded and ends up in a river as pollutants. The fuel burned to to make the aluminum into a can produces smoke that pollutes the air. The process used to make the soda to go into the can also produces pollutants. The consumer buying the can disposes of it as litter, another form of pollution.
5 Sources and SolutionsA great amount of pollution is tied directly to energy use. The world’s heavy dependence on fossil fuels has made pollution a major concern. The activities involved in finding and using fossil fuels have led to land, air and water pollution.Solutions can involve new ways to regulate and reuse materials. Solutions can also involve alternative energy to replace fossil fuels.
8 Land PollutionMost of the energy (90%) used comes form fossil fuels. Solar, wind, water and other alternative energy resources account for only 5%. Nuclear energy accounts for the other 5%. Obtaining both fossil fuels and nuclear energy can pollute the Earth.
9 CoalThe use of coal was an important step in the industrialization of the United States. Coal near the surface is strip mined. This process badly damages the land and causes soil and land pollution. Fertile topsoil is buried under tons of rock. When the rock is exposed to precipitation, acids and other harmful chemical seep into the ground, polluting the soil and land.
10 Hazardous WastesWastes from factories may pollute the land with toxic chemicals, called hazardous wastes. Hazardous wastes can cause death or serious damage to human health. Factories that produce fuels and petrochemicals from petroleum are the major sources of hazardous waste. When improperly stored in barrels buried in dumps, the wastes seep into the soil.
11 Management of Hazardous Wastes The best solution is to produce less hazardous wastes.In some cases, industries can reuse the wastes.Other wastes might be chemically treated to change the toxic substances they contain into nontoxic substances.
12 Radioactive WastesRadioactive wastes are the wastes produced as a result of the production of energy in nuclear power plants. Radioactive wastes are classified as either high-level or low-level. High-level wastes are primarily the used fuel rods from a nuclear reactor. Low-level wastes may include contaminated equipment used in the power plant.
13 Disposing of Radioactive Wastes Low-level wastes decay quickly. High-level wastes may of half-lives of 10,000 years or more. Isolating them from the environment for that length of time is almost impossible. In the past, high-level wastes were sealed in concrete or glass containers. The containers usually began to corrode or leak.
14 New Method of DisposalA new method of disposal has been proposed. Wastes can be buried in rock formations that are not subject to movement of in salt mines. This is known as Geologic disposal. Disposal in ocean beds is another alternative. Some scientists have suggested shooting rockets carrying high-level wastes into the sun.
15 Solid WastesAmericans produce about 11 billion tons of solid wastes every year. Solid wastes are useless, unwanted or discarded materials. They include agricultural wastes, commercial and industrial wastes and household wastes. Another word for solid waste is garbage. Mountains of garbage once surrounded cities.
16 Sanitary LandfillsOne way to deal with solid waste dumps is to cover them with thick layers of soil. In 1976 the United States Congress prohibited open dumps. They ruled that all existing open dumps were to be converted to sanitary landfills. All garbage is compacted and covered at least once a day with a layer of soil. Once filled they can be used as parks.
17 Problems with Landfills A problem with sanitary landfills is that when compacted garbage begins to decompose and methane gas is produced. It burns easily and is a fire hazard. Gas wells need to be installed. Wastes can ooze out of landfills and pollute the surrounding soil. The biggest problem is finding a place to put them.
18 Ocean DumpingAt one time, solid wastes were commonly towed offshore and dumped into the ocean. Much of the debris has washed up on beaches. Today some debris is still dumped.
19 Burning GarbageBurning garbage in open dumps and in the incinerators of apartment buildings and hospitals was used at one time. Because burning releases harmful gases, the practice is being halted. Sometimes the old incinerators are replaced with highly efficient incinerators. Some buildings use waste to energy incinerators. The heat produced is used to convert water into steam which is then used to generate electricity or heat the building.
20 Recycling Solid WasteMost environmentalists prefer recycling. Recycling not only gets rid of solid waste but also creates useful materials.
22 Air PollutionThe most significant source of air pollution is motor vehicles. The air is made up of oxygen, nitrogen, carbon dioxide, and water vapor. When fossil fuels are burned, pollutants enter the air. The gasoline burned in the engines of automobiles contains hydrocarbons. Pollution occurs when the gasoline is not completely burned in the engine. Some hydrocarbons as well as carbon monoxide enter the air.
23 SmogHydrocarbons, carbon monoxide and several other gases often react in sunlight to form a thick brownish haze called smog. Smog contains chemicals that irritate the eyes and make breathing difficult. Smog is very dangerous for people with asthma. Smog can also damage or kill plants. Smog can build up in a temperature inversion. This happens in Los Angeles.
24 Temperature Inversion A temperature inversion occurs when cool air near the Earth’s surface becomes trapped under a layer of warm air. Normally, cool air is heated by the Earth’s surface and rises, taking pollutants with it. But during a temperature inversion, the layer of warmer air acts as a lid and the pollutants are trapped in the cooler air near the surface. In the 1940’s some died and others were hospitalized in Donora, PA during a temperature inversion.
25 Acid RainFactories and cars release many pollutants into the air. Some of these pollutants include sulfur and nitrogen compounds called oxides. In the atmosphere, sulfur oxides and nitrogen oxides combine with water vapor and form acids: sulfuric and nitric. These acids fall to Earth as precipitation known as acid rain.
26 Problems with Acid Rain Very often acid rain falls many kilometers away from the original source of the pollution. Acid rain from factories in Germany, France and Great Britain killed fish and trees in Sweden. The best way to control acid rain is to burn low-sulfur coal but it is expensive.
27 Indoor Air PollutionIndoor pollution is a serious problem. Some appliances used in homes and offices give off potentially dangerous gases. In addition, often the houses are insulated in order to be energy efficient. Pollutants that might otherwise escape through cracks are trapped inside. One of the leading causes of indoor pollution is smoking.
29 Water PollutionMore and more of the water on Earth is becoming unusable. One reason for a shortage of water is water pollution. Obtaining and using energy resources are the major causes of water pollution.
30 Sources of Water Pollution Acid RainStrip MiningOil SpillsNuclear powerHazardous WastesSewage and Agricultural Runoff
31 Acid RainWhen acid rain falls into lakes, rivers and streams, they increase the acidity level of the water. Most fishes and other organisms that live in water can survive in only a narrow range of acidity. Acid rain kills many of the organisms living in the water.
32 Strip MiningStrip mining for coal releases pollutants that may run off into lakes and streams or may seep in to the soil to contaminate groundwater.
33 Oil SpillsPetroleum is often found under the ocean floor. To obtain this petroleum, offshore oil wells are constructed. Drilling accidents occurs and large amounts of oil spill into the oceans. Oil spills also occur when tanker carrying oil are damaged. Tankers also deliberately flush waste oil into the ocean. Plants and animals are killed.
34 Nuclear PowerWater is needed to cool the reactors in nuclear power plants. Cold water from lakes and rivers is used for this process. As a result of this a lot of hot water is generated. This heated water is then discharged in to lakes. This causes the temperature to rise. This temperature increase is called thermal pollution since organisms die when temperatures rise.
35 Radioactive WastesRadioactive wastes can also be a sources of ling-term water pollution. Radioactive wastes stored in underground containers may leak and pollute groundwater. Pollution of the oceans occurs if these wastes are dumped in the ocean.
36 Hazardous WastesPrior to the 1970’s many industries dumped chemicals and other hazardous wastes directly into streams and other nearby bodies of water. Today they are not deposited directly into water, instead they are buried. Often leaks occur and the groundwater is polluted. Illegal dumping, called midnight dumping, also occurs.
37 SewageThe greatest threat to human health comes form sewage. Sewage is the waste material that is carried away by sewers and drains. Sometimes it is dumped directly into streams. This sewage often contains disease-causing bacteria and viruses. Drinking water may become contaminated.
38 Danger to FishFish living in polluted water are also unfit for human consumption. Untreated sewage is also harmful to the fish and other organisms that live in the water. Bacteria in the water break down the sewage. In the process, the bacteria use oxygen. If too much oxygen is used, fish and other organism may die from lack of oxygen.
39 Agricultural RunoffThe runoff of agricultural wastes and chemicals from farmlands also contributes to water pollution. Chemicals such as Phosphates and nitrates are used in fertilizers to improve the growth of crops. When fertilizers run off the land in to a lake, they stimulate the growth of algae. The algae then use up the oxygen in the lake. Pesticides also enter the water.
40 What Can Be Done About Pollution? Pollution can be reduced by conserving energy, by finding cleaner ways to use energy, and by making sure that wastes are disposed of in the safest possible ways.
41 ConservationConservation is the wise use of natural resources so that they will not used up too quickly or used in a way that will damage the environment. The environment benefits two ways. First, nonrenewable resources last longer. Second, pollution is reduced.
42 Examples of Conservation RecyclingCarpoolingPublic TransportationTurning down the thermostat in the winter and turning up in the summerInsulate homesUse less water
43 New TechnologiesNew technologies can reduce pollution by creating cleaner and more efficient ways of obtaining and using energy resources. Technology can also help develop alternatives to fossil fuels.
44 Scrubber SystemsThe burning of coal has been made less damaging to the environment by the use of scrubber systems. A scrubber system works like a shower. As sulfur oxides are released from burning coal, a high-pressure spray of water dissolves the oxides before they can react with the water vapor. They can be used on smokestacks.
45 Oil Drilling and Spills New methods have been used to drill for oil under the ocean floor in order to reduce underwater leaks. Several new methods have been developed for cleaning up oil spills with vacuum systems. Oil-eating bacteria have also been developed.
46 Waste DisposalHazardous waste should be separated from industrial waste.Hazardous waste should be reused or recycled when possible.The waste should be treated chemically to destroy the toxic materials they contain.The wastes should be buried in landfills with many safeguards to prevent leaks.
47 Everyone’s Responsibility Pollution is mainly caused by the activities of people. It is important to realize that the activities of people can also reduce pollution. Everyone can help!