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(单词翻译:双击或拖选)
Air Pollution
托福阅读材料推荐:空气污染问题
Comes From Many Sources
Here's what you need to know about the warming planet, how it's affecting us, and what's at stake.
Smog hanging over cities is the most familiar and obvious form of air pollution. But there are different kinds of pollution—some visible, some invisible—that contribute to global warming. Generally any substance that people introduce into the atmosphere that has damaging effects on living things and the environment is considered air pollution.
Carbon dioxide, a greenhouse gas, is the main pollutant1 that is warming Earth. Though living things emit carbon dioxide when they breathe, carbon dioxide is widely considered to be a pollutant when associated with cars, planes, power plants, and other human activities that involve the burning of fossil fuels such as gasoline and natural gas. In the past 150 years, such activities have pumped enough carbon dioxide into the atmosphere to raise its levels higher than they have been for hundreds of thousands of years.
Other greenhouse gases include methane—which comes from such sources as swamps and gas emitted by livestock—and chlorofluorocarbons (CFCs), which were used in refrigerants and aerosol2 propellants until they were banned because of their deteriorating3 effect on Earth's ozone4 layer.
Another pollutant associated with climate change is sulfur5 dioxide, a component6 of smog. Sulfur dioxide and closely related chemicals are known primarily as a cause of acid rain. But they also reflect light when released in the atmosphere, which keeps sunlight out and causes Earth to cool. Volcanic7 eruptions8 can spew massive amounts of sulfur dioxide into the atmosphere, sometimes causing cooling that lasts for years. In fact, volcanoes used to be the main source of atmospheric9 sulfur dioxide; today people are.
Industrialized countries have worked to reduce levels of sulfur dioxide, smog, and smoke in order to improve people's health. But a result, not predicted until recently, is that the lower sulfur dioxide levels may actually make global warming worse. Just as sulfur dioxide from volcanoes can cool the planet by blocking sunlight, cutting the amount of the compound in the atmosphere lets more sunlight through, warming the Earth. This effect is exaggerated when elevated levels of other greenhouse gases in the atmosphere trap the additional heat.
Most people agree that to curb10 global warming, a variety of measures need to be taken. On a personal level, driving and flying less, recycling, and conservation reduces a person’s "carbon footprint"—the amount of carbon dioxide a person is responsible for putting into the atmosphere.
On a larger scale, governments are taking measures to limit emissions11 of carbon dioxide and other greenhouse gases. One way is through the Kyoto Protocol12, an agreement between countries that they will cut back on carbon dioxide emissions. Another method is to put taxes on carbon emissions or higher taxes on gasoline, so that people and companies will have greater incentives13 to conserve14 energy and pollute less.
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1 pollutant | |
n.污染物质,散布污染物质者 | |
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2 aerosol | |
n.悬浮尘粒,气溶胶,烟雾剂,喷雾器 | |
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3 deteriorating | |
恶化,变坏( deteriorate的现在分词 ) | |
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4 ozone | |
n.臭氧,新鲜空气 | |
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5 sulfur | |
n.硫,硫磺(=sulphur) | |
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6 component | |
n.组成部分,成分,元件;adj.组成的,合成的 | |
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7 volcanic | |
adj.火山的;象火山的;由火山引起的 | |
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8 eruptions | |
n.喷发,爆发( eruption的名词复数 ) | |
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9 atmospheric | |
adj.大气的,空气的;大气层的;大气所引起的 | |
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10 curb | |
n.场外证券市场,场外交易;vt.制止,抑制 | |
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11 emissions | |
排放物( emission的名词复数 ); 散发物(尤指气体) | |
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12 protocol | |
n.议定书,草约,会谈记录,外交礼节 | |
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13 incentives | |
激励某人做某事的事物( incentive的名词复数 ); 刺激; 诱因; 动机 | |
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14 conserve | |
vt.保存,保护,节约,节省,守恒,不灭 | |
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