win10新电脑怎么刷win7:英语短文"pollution"

AIR POLLUTION

Sandstorms and the dust and gases from volcanoes pollute the earth's atmosphere naturally. But the most serious kind of air pollution comes from people. Factories, power stations, and rehicles exhausts[1] pump harmful gases into the air, contributing to global warming, causing acid rain[2], and destroying the ozone layer. On a much smaller scale, air pollution causes all sorts of breathing problems. There are no simple solutions to air pollution, but people could reduce air pollution by saving energy and reducing harmful emissions from vehicle exhausts and power stations.
When a volcano erupts, dust is blasted[3] high above the troposphere and may take weeks to be carried around the weather zone, so cannot be washed out of the air by rain. It will eventually fall to the earth after a few years.
Air pollution is at its worst over big cities where millions of people live, work, and travel about in cars, buses, and trucks. Factory chimmeys can be fitted with devices to cut down[4] air pollution, but this is expensive. If better pubic transport and cycle lanes were available in towns and cities, people would be less likely to use their cars, reducing the overall amount of pollution.
Smoking cigarettes adds to the general levels of air pollution as well as damaging our health. Cigarette smoke contains chemicals that can cause cancer, a gas which stops oxygen being taken into the blood and a substance called nicotine, which raises blood pressure and makes the heart beat faster. No-smoking areas cut down on this pollution and save non-smokers breathing in other people's cigarette smoke.

空气污染

沙暴和火山爆发喷出的尘埃和有毒气体自然而然地对地球大气造成的污染，然而最严重的空气污染却来自人类。工厂、火力发电站和车辆将有害废气排放到空气中，是造成全球气候变暖，出现酸雨，破坏臭氧层的罪魁祸首。就更小的范围来看，空气污染会引发各种呼吸道疾病。没有解决空气污染的简单办法，但人们可以通过节约能源、减少车辆和火力发电站的有害气体排放来达到降低污染的目的。

火山爆发时，尘埃被高高喷射入对流层以上的空间，需要几个星期才飘浮移至气象层，因而雨水无法将其从大气中冲走。几年之后，尘埃将最终漂落在地球上。

好几百万人在城市里工作、生活，还以轿车、公共汽车和卡车为交通工具，因而这种百万人口的城市空气污染最为严重。工厂烟囱可以安装滤清装置以减少空气污染，但成本昂贵。如能改善城镇公共交通，并设置自行车车道，人们就不再会热衷于使用自家汽车，从而达到全面减少污染的目的。

吸烟不仅对健康有害，而且增加空气污染程度。香烟雾含有多种有害物质：不仅有致癌化学物质、有某种能阻止氧气进入血液的气体，还有引起血压增高、心速加快的被称为尼古丁的物质。设立禁烟区有助于减少污染，并能使不吸烟者免受被动吸烟之害。

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Pollution

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.

高中课本里有

污染