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  • 空气污染

    Thick smog and dust cover a polluted city skyline, highlighting air pollution issues.

    What is this haze?
    ::这是什么烟雾?

    This picture shows a thick layer of smog and dust over a very polluted city. Smog in the air is a serious health hazard for people living in many big cities around the globe. Smog is one example of air pollution.
    ::这张图片显示,在一个污染严重的城市上,有一层厚厚的烟雾和尘埃。 空气中的烟雾对全球许多大城市的居民的健康构成严重的危害。 烟雾是空气污染的一个例子。

    Outdoor Air Pollution
    ::室外空气污染

    Air is all around us. Air is essential for life. Sometimes, humans can pollute the air. For example, releasing smoke and dust from factories and cars can cause air pollution . Air pollution is due to chemical substances and particles released into the air mainly by human actions. This pollution affects entire around the world. Pollution can also cause many human health problems, and it can also cause death. Air pollution can be found both outdoors and indoors.
    ::空气环绕着我们周围。空气是生命的关键。有时,人类可以污染空气。例如,从工厂和汽车中释放烟尘和灰尘可以造成空气污染。空气污染主要来自化学物质和通过人类行动释放到空气中的微粒。这种污染影响到全世界。污染还可能造成许多人类健康问题,也可能造成死亡。空气污染既存在于户外,也存在于室内。

    Outdoor air pollution is made of chemical particles. When smoke or other pollutants enter the air, the particles found in the pollution mix with the air. Air is polluted when it contains many large toxic particles. Outdoor air pollution changes the natural characteristics of the atmosphere . Primary pollutants are added directly to the atmosphere. Fires add primary pollutants to the air. Particles released from the fire directly enter the air and cause pollution ( Figure  ). Burning of fossil fuels such as oil and coal is a major source of primary pollutants ( Figure  ).
    ::室外空气污染是由化学颗粒造成的。当烟雾或其他污染物进入空气时,在与空气混合的污染中发现微粒;当空气含有许多大的有毒微粒时,空气受到污染; 室外空气污染改变大气的自然特性; 初级污染物直接添加到大气中; 火将主要污染物添加到空气中; 火灾释放的粒子直接进入空气并造成污染(图 )。燃烧石油和煤炭等化石燃料是主要污染物的主要来源(图 )。

    Secondary pollutants are formed when primary pollutants interact with sunlight, air, or each other. They do not directly cause pollution. However, when they interact with other parts of the air, they do cause pollution. For example, ozone is created when some pollutants interact with sunlight. High levels of ozone in the atmosphere can cause problems for humans.
    ::次要污染物是在初级污染物与阳光、空气或相互之间发生相互作用时形成的,它们不会直接造成污染,但是,当它们与其他空气部分发生相互作用时,它们确实会造成污染,例如,有些污染物与阳光发生相互作用时,臭氧就会产生,大气中的高臭氧水平可能会对人类造成问题。

    A forest fire releasing smoke and flames, illustrating a source of outdoor air pollution.
    Wildfires, either natural or human-caused, release particles into the air, one of the many causes of air pollution.
    Factories emitting smoke into the atmosphere, illustrating the source of air pollution.
    A major source of air pollution is the burning of fossil fuels from factories, power plants, and motor vehicles.

    Sources of Outdoor Air Pollution
    ::室外空气污染源

    Most air pollutants can be traced to the burning of fossil fuels. Fossil fuels are burned during many processes, including in power plants to create electricity, in factories to make machinery run, in power stoves and furnaces for heating, and in waste facilities. Perhaps one of the biggest uses of fossil fuels is in transportation. Fossil fuels are used in cars, trains, and planes.
    ::多数空气污染物可以追溯到化石燃料的燃烧,化石燃料在许多过程中被燃烧,包括发电厂发电、工厂机械操作、电炉和供暖炉以及废物处理设施。 也许化石燃料的最大用途之一是运输。 化石燃料用于汽车、火车和飞机。

    Air pollution can also be caused by , such as cattle ranching and the use of fertilizers and pesticides. Other sources of air pollution include the production of plastics, refrigerants, and aerosols, in nuclear power and defense, from landfills and mining, and from biological warfare.
    ::其他空气污染来源包括生产塑料、制冷剂和气溶胶、核能和核防御、填埋场和采矿以及生物战。

    Acid Rain
    ::酸酸雨雨

    One result of air pollution is acid rain . Acid rain is precipitation with a low (acidic) pH. This rain can be very destructive to wildlife. When acid rain falls in forests , freshwater habitats , or soils, it can kill and life. It causes this damage because of its very low pH. Sulfur oxides and nitrogen oxides in the air both cause acid rain to form ( Figure  ). Sulfur oxides are chemicals that are released from coal-fired power plants. Nitrogen oxides are released from motor vehicle exhaust.
    ::空气污染的一个后果是酸雨。酸雨是低(酸)pH值的降水。这种雨对野生动物具有极大的破坏力。当酸雨落在森林、淡水生境或土壤中时,它会杀死生命。它会造成这种损害,因为它的pH值非常低。硫氧化物和空气中的氮氧化物都会导致酸雨形成(图 )。硫氧化物是燃煤发电厂释放出来的化学品。氧化氮从机动车排气排气中释放出来。

    Forest in the Jizera Mountains showing tree die-off due to acid rain effects.
    A forest in the Jizera Mountains of the Czech Republic shows effects caused by acid rain. What do you observe?

    Global Warming
    ::全球变暖

    Pollutants also affect the atmosphere through their contribution to global warming . Global warming is an increase in the Earth’s temperature. It is thought to be caused mostly by the increase of greenhouse gases like carbon dioxide. Greenhouse gases can be released by factories that burn fossil fuels. Over the past 20 years, burning fossil fuels has produced about three-quarters of the carbon dioxide from human activity. The rest of the carbon dioxide in the atmosphere is there because of deforestation, or cutting down trees ( Figure ). Trees absorb carbon dioxide during , so when trees are cut down, they cannot remove carbon dioxide from the air.
    ::全球变暖是地球温度的上升。 人们认为,全球变暖主要是二氧化碳等温室气体的增加造成的。 燃烧化石燃料的工厂可以释放温室气体。 在过去20年中,燃烧化石燃料从人类活动中产生大约四分之三的二氧化碳。 大气中的其他二氧化碳是由于砍伐森林或砍伐树木(图 ) 。 树木在砍伐树木期间吸收二氧化碳,因此当树木被砍伐时,它们无法从空气中去除二氧化碳。

    Deforested area from agriculture in southern Mexico, illustrating the impact of carbon emissions.
    Deforestation, shown here as a result of burning for agriculture in southern Mexico, has produced significant increases in carbon dioxide emissions over the past 20 years.

    This increase in global temperature will cause the sea level to rise. It is also expected to produce an increase in extreme weather events and change the amount of precipitation. Global warming may also cause food shortages and species extinction .
    ::全球气温的上升将导致海平面升高,预计还会增加极端天气事件,改变降水量,全球升温还可能导致粮食短缺和物种灭绝。

    Summary
    ::摘要

    • Air pollution is caused by chemical substances and particles released into the air, mainly by human activities.
      ::空气污染是由化学物质和释放到空气中的微粒造成的,主要是人类活动造成的。
    • The major cause of outdoor air pollution is the burning of fossil fuels.
      ::室外空气污染的主要原因是燃烧化石燃料。
    • Problems caused by the burning of fossil fuels include acid rain and global warming.
      ::燃烧化石燃料引起的问题包括酸雨和全球升温。

    Explore More
    ::探索更多

    Use the resource below to answer the questions that follow.
    ::利用以下资源回答以下问题。

    • Human Pollution at (2:15)
      ::人类污染时间(2:15)
    1. What are pollutants?
      ::什么是污染物?
    2. What are three sources of pollutants?
      ::污染物的三种来源是什么?
    3. What are the two main categories of pollutants?
      ::两大类污染物是什么?

    Review
    ::回顾

    1. What is air pollution?
      ::什么是空气污染?
    2. What's the difference between primary and secondary pollutants? Give examples of each.
      ::初级和二级污染物之间有什么区别?请举例说明每一种污染物。
    3. What are three ways that polluting fossil fuels are burned?
      ::燃烧污染化石燃料的三种方式是什么?
    4. Why is acid rain dangerous
      ::为什么酸雨危险