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The contamination of the air, water, or earth by harmful or potentially harmful substances.
The U.S. environmental movement in the 1960s emerged from concerns that air, water, and soil were being polluted by harmful chemicals and other toxic substances. During the industrial revolution of the nineteenth century, the mass production of goods created harmful wastes, much of which was dumped into rivers and streams. The twentieth century saw the popular acceptance of the automobile and the internal combustion engine, which led to the pollution of the air. Rapidly expanding urban centers began to use rivers and lakes as repositories for sewage.
Land pollution involves the depositing of solid wastes that are useless, unwanted, or hazardous. Types of solid waste include garbage, rubbish, ashes, sewage-treatment solids, industrial wastes, mining wastes, and agricultural wastes. Most solid waste is buried in sanitary landfills. A small percentage of municipalities incinerate their refuse, while composting is rarely employed.
Modern landfills attempt to minimize pollution of surface and groundwater. They are now located in areas that will not flood and that have the proper type of soil. Solid wastes are compacted in the landfill and are vented to eliminate the buildup of dangerous gases. Hazardous wastes, including toxic chemicals and flammable, radioactive, or biological substances, cannot be deposited in landfills, and the management of these wastes is subject to federal and state regulation. The federal government's Resource Conservation and Recovery Act (42 U.S.C.A. § 6901 et seq.) is a comprehensive regulatory statute that creates a "cradle to grave" system of controlling the entire hazardous waste life cycle.
Nuclear wastes are especially troublesome. Congress passed the Nuclear Waste Policy Act of 1982 (42 U.S.C.A. §§ 10101–226), which directed the department of energy to formally begin planning the disposal of nuclear wastes and imposed most of the costs of disposal on the Nuclear Power industry. Since 1986 the Department of Energy has been unsuccessful in finding an acceptable site. Yucca Mountain, Nevada, is the only place earmarked for a site study. Solid waste pollution has been reduced by recovering resources rather than burying them. Resource recovery includes massive systems that burn waste to produce steam, but it also includes the recycling of glass, metal, and paper from individual consumers and businesses. The elimination of these kinds of materials from landfills has prevented pollution and extended the period during which landfills can receive waste.
Land pollution also involves the accumulation of chemicals in the ground. Modern agriculture, which has grown dependent on chemical fertilizers and chemicals that kill insects, has introduced substances into the soil that kill more than pests. For many years the chemical DDT was routinely sprayed on crops to control pests. It was banned when scientists discovered that the chemical entered the food chain and was harming wildlife and possibly humans.
Air Pollution is regulated by the federal government. The Clean Air Act was originally enacted in 1970 and was extensively amended in 1977 and again in 1990 (42 U.S.C.A. §§ 7401–7626; Pub. L. No. 95-95 [1977 amendments]; Pub. L. No. 101-549 [1990 amendments]). Under its provisions, every stationary and mobile pollution source must comply with emission standards as a means of cleaning up the ambient air quality in the area. This has meant that automobile emission control systems have been created and improved to meet more stringent air quality standards. Coal-burning electric power plants have been required to install filtration systems on their smokestacks, and manufacturing facilities have had to install equipment that "scrubs" polluted air clean.
Water Pollution has existed longer than any other type of pollution. Depositing liquid and solid wastes in rivers, streams, lakes, and oceans was convenient and inexpensive for a company or municipality, but it eventually destroyed the ecosystems found in the water. Many large rivers became nothing more than sewers. Most troubling was the polluting of groundwater, creating serious health hazards for those people who drank water containing toxic substances.
The federal Clean Water Act (CWA) was originally enacted in 1972 and then amended in 1977 and 1987 (33 U.S.C.A. §§ 1251–1387; Pub. L. No. 95-217 [1977 amendments]; Pub. L. No. 100-4 [1987 amendments]). The CWA seeks to eliminate the "discharge of pollutants into navigable waters," to make water safe for people to fish and swim in, and to end the "discharges of toxic pollutants in toxic amounts." The CWA seeks to accomplish these goals through a variety of regulatory strategies.