作业帮求一个关于环境污染的例子,要英文的.一个趣味的关于环境污染的例子,要英文的.
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求一个关于环境污染的例子,要英文的.一个趣味的关于环境污染的例子,要英文的.
求一个关于环境污染的例子,要英文的.
一个趣味的关于环境污染的例子,要英文的.
求一个关于环境污染的例子,要英文的.一个趣味的关于环境污染的例子,要英文的.
Chlorofluorocarbons (CFCs)
CFCs are lowering the average concentration of ozone in the stratosphere."Since 1978 the use of CFCs in aerosol cans has been banned in the United States,Canada,and most Scandinavian countries.Aerosols are still the largest use,accounting for 25% of global CFC use".(Miller 448) Spray cans,discarded or leaking refrigeration and air conditioning equipment,and the burning plastic foam products release the CFCs into the atmosphere.Depending on the type,CFCs stay in the atmosphere from 22 to 111 years.Chlorofluorocarbons move up to the stratosphere gradually over several decades.Under high energy ultra violet (UV) radiation,they break down and release chlorine atoms,which speed up the breakdown of ozone (O3) into oxygen gas (O2).
Chlorofluorocarbons,also known as Freons,are greenhouse gases that contribute to global warming.Photochemical air pollution is commonly referred to as "smog".Smog,a contraction of the words smoke and fog,has been caused throughout recorded history by water condensing on smoke particles,usually from burning coal.With the introduction of petroleum to replace coal economies in countries,photochemical smog has become predominant in many cities,which are located in sunny,warm,and dry climates with many motor vehicles.The worst episodes of photochemical smog tend to occur in summer.