Section outline

  • General

    Collapse all Expand all

  • 臭氧消耗

    Lesson
    ::经验教训

     

    Children playing and splashing water with an adult in a sunny outdoor setting.
     

    How do you protect yourself from the Sun?
    ::你如何保护自己不受太阳的伤害?

    You probably already use sunscreen when you play outside in the summer. The  ozone layer  in Earth’s   also helps protect us from the Sun’s  ultraviolet light . But for several years in the 1990s, the  ozone hole  moved north from Antarctica, effecting the world’s southernmost city of Punta Arenas, Chile. Too much of the Sun's harmful UV radiation got through, causing an increase in sunburns, skin cancer, and vision problems in both humans and livestock. Although the ozone hole started to shrink again, most residents continue to wear long sleeves and use sunblock outdoors.
    ::夏季,你可能已经使用防晒霜了。 地球的臭氧层也帮助我们免受太阳紫外线光照射。 但是,在1990年代的几年里,臭氧洞从南极向北移动,影响着世界上最南端城市智利蓬塔阿雷纳斯。 太多的太阳有害的紫外辐射通过,导致太阳晒伤、皮肤癌以及人类和牲畜的视力问题增加。 尽管臭氧洞开始再次缩小,但大多数居民继续穿长袖,在户外使用防晒霜。

    Loss of High-Level Ozone
    ::高臭氧损失

    Ozone  near the ground harms human health. Ground-level ozone is a pollutant. But the ozone layer in the stratosphere protects us from harmful solar rays. That’s why people were alarmed in the 1980s to learn that there was a hole in the ozone layer.
    ::臭氧接近地面会危害人类健康。 地面臭氧是一种污染物。 但平流层的臭氧层保护着我们免受有害的太阳射线的危害。 这就是人们在1980年代惊恐地得知臭氧层存在空洞的原因。

    Cause of Ozone Loss
    ::臭氧损失的原因

    What’s destroying the ozone layer? The chief cause is chlorofluorocarbons (CFCs). These are human-made chemicals that contain the  element  chlorine (Cl). In the past, CFCs were widely used in spray cans, refrigerators, and many other products. CFCs are  stable  compounds that can remain in the  atmosphere  for hundreds of years.
    ::是什么在破坏臭氧层? 其主要原因是氯氟化碳(CFCs ) 。 这些是含有氯元素(Cl)的人为化学品。 过去,氯氟化碳被广泛用于喷雾罐、冰箱和许多其他产品。 氯氟化碳是稳定的化合物,可以留在大气中数百年。

    Once CFCs are in the air, they float up into the stratosphere. What happens next is pictured below ( Figure   ). Sunlight breaks apart the molecules. This releases their chlorine  ions  (Cl). The free chlorine ions may then combine with oxygen ions in ozone. This breaks down the ozone molecules into an oxygen  molecule  and an oxygen ion. One CFC molecule can break down as many as 100,000 ozone molecules in this way! These forms of oxygen do not protect the  planet  from  ultraviolet radiation .
    ::一旦氟氯化碳进入空气,它们就会漂浮到平流层中。接下来发生的情况将在下面(图 ) 描绘(图 ) 。 日光破碎分子。 这释放了它们的氯离子( Cl ) 。 自由氯离子可能会与臭氧中的氧离子结合。 这可以将臭氧分子分解成氧分子和氧离子。 一种氟氯化碳分子可以这样将多达100,000个臭氧分子分解出来! 这些形式的氧不能保护地球免受紫外线辐射的危害。

    Process diagram showing how CFCs deplete the ozone layer and increase UV radiation.
     
    CFCs break down ozone in the stratosphere.

    Ozone Hole
    ::臭氧洞

    Most ozone loss it taking place over the South Pole and Antarctica. This is the   of the ozone hole. The  ozone hole  is a region in the stratosphere where there is less ozone than normal. Conditions are just right for ozone destruction because it is exceedingly cold. The ozone hole is also seasonal. The hole forms during the early part spring in the  Southern Hemisphere  and then grows northward ( Figure   ). The ozone layer is also thinner over the  Northern Hemisphere .
    ::大部分臭氧损失发生在南极和南极上空。这是臭氧空洞。臭氧空洞是平流层中臭氧比正常少的一个区域。由于臭氧极冷,因此情况正好可以破坏臭氧。臭氧空洞也是季节性的。在南半球的早期春季,洞状形成,然后向北生长(图 )。臭氧层在北半球也较薄。

    Map showing ozone depletion over Antarctica, highlighting the ozone hole in the stratosphere.
     
    The hole in the ozone layer occurs over Antarctica. How do you think the hole in the ozone layer could affect life on Earth?

    Effects of Ozone Loss
    ::臭氧损损的影响

    With less ozone in the stratosphere, more UV rays reach the ground. More UV rays increase skin cancer rates. Just a 1 percent loss of ozone causes a 5 percent increase in skin cancer. More UV rays also harm plants and  phytoplankton . As a result, they produce less food. This may affect entire  ecosystems .
    ::随着平流层臭氧减少,更多的紫外线到达地面。更多的紫外线增加了皮肤癌率。只有1%的臭氧损失导致皮肤癌增加5%。更多的紫外线也危害植物和浮游植物。结果,它们生产的食物较少。这可能影响到整个生态系统。

    Protecting the Ozone Layer
    ::保护臭氧层维也纳公约》

    The Montreal Protocol is a worldwide agreement on air pollution. It focuses on CFCs. It was signed by many countries in 1987. It controls almost 100 chemicals that can damage the ozone layer. Its aim is to return the ozone layer to its normal state.
    ::《蒙特利尔议定书》是一项全球性空气污染协定,重点是氟氯化碳,1987年许多国家签署了该议定书,控制了近100种可能损害臭氧层的化学品,目的是将臭氧层恢复到正常状态。

    The Montreal Protocol has been effective in controlling CFCs. By 1995, few CFCs were still being used. But the ozone hole kept growing for several years after that because of the CFCs already in the atmosphere. It peaked in 2006. Since then, it has been somewhat smaller. The Montreal Protocol is a shining example of how nations can come together to solve a global environmental problem.
    ::《蒙特利尔议定书》有效地控制了氟氯化碳,到1995年,氟氯化碳仍然很少被使用,但此后几年,臭氧空洞一直在增加,因为氟氯化碳已经存在于大气中,2006年达到顶峰,自那时起,臭氧空洞规模小一些,《蒙特利尔议定书》是各国如何共同解决全球环境问题的光辉范例。

    Summary
    ::摘要

    • CFCs float up into the stratosphere where they break apart. The chlorine pulls an oxygen ion off of an ozone molecule and destroys it.
      ::氯从臭氧分子中提取氧离子并摧毁它。
    • The ozone hole forms over Antarctica in the spring.
      ::春天,臭氧洞在南极洲上空形成。
    • Ozone loss increases the amount of high-energy ultraviolet radiation that strikes Earth. This can cause ecological and health problems.
      ::臭氧损失增加了撞击地球的高能紫外线辐射量,可能造成生态和健康问题。

    Review
    ::回顾

    1. How do CFCs destroy ozone?
      ::氟氯化碳如何销毁臭氧?
    1. What is the ozone hole, and where is it found?
      ::臭氧洞是什么? 在哪里找到的?
    1. What effect does the ozone hole have on life, especially human life?
      ::臭氧洞对生命,特别是人类生命有何影响?

    Explore More
    ::探索更多

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

     

     

    1. What is the purpose of the ozone layer?
      ::臭氧层的目的何在?
    1. Why is the ozone layer so fragile?
      ::为什么臭氧层如此脆弱?
    1. How much did ozone decrease between 1979 and 1993? Where scientists surprised by this?
      ::从1979年到1993年,臭氧减少多少?科学家对此感到惊讶吗?
    1. Which satellite was launched to study the ozone? When?
      ::发射哪颗卫星研究臭氧?何时发射?

     

     

    1. What caused this ozone loss?
      ::是什么原因造成臭氧流失的?