評論
打印
Part 4 Air Pollution 空氣污染
Air is the ocean we breathe. Air supplies us with oxygen which is essential for our bodies to live. Air is 99.9% nitrogen, oxygen, water vapor and inert gases. Human activities can release substances into the air, some of which can cause problems for humans, plants, and animals.
There are several main types of pollution and well-known effects of pollution which are commonly discussed. These include smog, acid rain, the greenhouse effect, and "holes" in the ozone layer. Each of these problems has serious implications for our health and well-being as well as for the whole environment.
One type of air pollution is the release of particles into the air from burning fuel for energy. Diesel smoke is a good example of this particular matter. This type of pollution is sometimes referred to as "black carbon" pollution. The exhaust from burning fuels in automobiles, homes, and industries is a major source of pollution in the air. Some authorities believe that even the burning of wood and charcoal in fireplaces and barbeques can release significant quantities of soot into the air.
Another type of pollution is the release of noxious gases, such as sulfur dioxide, carbon monoxide, nitrogen oxides, and chemical vapors. These can take part in further chemical reactions once they are in the atmosphere, forming smog and acid rain.
Smog is a type of large-scale outdoor pollution. It is caused by chemical reactions between pollutants derived from different sources, primarily automobile exhaust and industrial emissions. Cities are often centers of these types of activities, and many suffer from the effects of smog, especially during the warm months of the year.
Another consequence of outdoor air pollution is acid rain. When a pollutant, such as sulfuric acid combines with droplets of water in the air, the water or snow can become acidified . The effects of acid rain on the environment can be very serious. It damages plants by destroying their leaves, it poisons the soil, and it changes the chemistry of lakes and streams. Damage due to acid rain kills trees and harms animals, fish, and other wildlife.
The Greenhouse Effect, also referred to as global warming, is generally believed to come from the build up of carbon dioxide gas in the atmosphere. Carbon dioxide is produced when fuels are burned. Plants convert carbon dioxide back to oxygen, but the release of carbon dioxide from human activities is higher than the world's plants can process. The situation is made worse since many of the earth's forests are being removed, and plant life is being damaged by acid rain. Thus, the amount of carbon dioxide in the air is continuing to increase. This buildup acts like a blanket and traps heat close to the surface of our earth. Changes of even a few degrees will affect us all through changes in the climate and even the possibility that the polar ice caps may melt.
Ozone depletion is another result of pollution. Chemicals released by our activities affect the stratosphere , one of the atmospheric layers surrounding earth. The ozone layer in the stratosphere protects the earth from harmful ultraviolet radiation from the sun. Ultraviolet radiation is known to cause skin cancer and has damaging effects on plants and wildlife.
Pollution also needs to be considered inside our homes, offices, and schools. Some of these pollutants can be created by indoor activities such as smoking and cooking.
In many countries in the world, steps are being taken to stop the damage to our environment from air pollution. Scientific groups study the damaging effects on plant, animal and human life. Legislative bodies write laws to control emissions. Educators in schools and universities teach students, beginning at very young ages, about the effects of air pollution.
The first step to solving air pollution is assessment . Researchers have investigated outdoor air pollution and have developed standards for measuring the type and amount of some serious air pollutants. Scientists must then determine how much exposure to pollutants is harmful. Once exposure levels have been set, steps can be undertaken to reduce exposure to air pollution. These can be accomplished by regulation of man-made pollution through legislation. Many countries have set controls on pollution emissions for transportation vehicles and industry.
Prevention is another key to controlling air pollution. The regulatory agencies mentioned above play an essential role in reducing and preventing air pollution in the environment.
In addition, it is possible to prevent many types of air pollution that are not regulated through personal, careful attention to our interactions with the environment. Only through the efforts of scientists, business leaders, legislators, and individuals can we reduce the amount of air pollution on the planet. This challenge must be met by all of us in order to assure that a healthy environment will exist for ourselves and our children.
所謂干潔空氣是指在自然狀態下的大氣，由混合氣體、水氣和雜質組成，當大氣中污染物質的濃度達到有害程度，以至破壞生態系統和人類正常生存和發展的條件，對人或物造成危害的現象叫做大氣污染。造成大氣污染的原因，既有自然因素又有人為因素，尤其是人為因素，如工業廢氣、燃燒、汽車尾氣和核爆炸等。隨著人類經濟活動和生產的迅速發展，在大量消耗能源的同時，同時也將大量的廢氣、煙塵物質排入大氣，嚴重影響了大氣環境的質量，特別是在人口稠密的城市和工業區域。
大氣中的二氧化碳濃度增加，阻止地球熱量的散失，使地球發生可感覺到的氣溫升高，這就是有名的“溫室效應”，致使地球氣溫上升。
隨著工業化和能源消費增多，酸性排放物也日益增多，它們進入空氣中，經過一系列化學作用就形成了酸雨。人們對酸性排放物已經有了控制，但仍然還有酸雨現象。大氣塵埃可能是造成酸雨問題的另一原因。
臭氧層是地球最好的保護傘，它吸收了來自太陽的大部分紫外線。然而近二十年的科學研究和大氣觀測發現：每年春季南極大氣中的臭氧層一直在變薄，事實上在極地大氣中存在一個臭氧“洞” 通過不斷的科學研究，人們發現人類社會活動釋放的物質嚴重的破壞了臭氧層，當然這種現象還受到這一地區獨特的氣象狀態（極渦、寒冷的平流層溫度、極地平流層云）的影響。
大氣被污染后，由于污染物質的來源、性質和持續時間的不同，被污染地區的氣象條件、地理環境等因素的差別，以及人的年齡、健康狀況的不同，對人體造成的危害也不盡相同。大氣污染對人體的危害主要表現為呼吸道疾病；對植物可使其生理機制受抑制，生長不良，抗病抗蟲能力減弱，甚至死亡；大氣污染還能對氣候產生不良影響，如降低能見度，減少太陽的輻射而導致城市佝僂病發病率的增加；大氣污染物能腐蝕物品，影響產品質量；近十幾年來，不少國家發現酸雨，雨雪中酸度增高，使河湖、土壤酸化、魚類減少甚至滅絕，森林發育受影響，這與大氣污染是有密切關系的。
大氣污染對氣候的影響很大，大氣污染排放的污染物對局部地區和全球氣候都會產生一定影響，尤其對全球氣候的影響，從長遠的觀點看，這種影響將是很嚴重的。由于人類對自然的嚴重破壞，在世界范圍內掀起了保護大氣環境的浪潮。許多國家圍繞大氣污染物的來源與歸宿，大氣化學過程中的反應機理及效應進行了大量的研究工作，促進了人類對一系列環境問題的認識。
Dialogue Script 對話原文
David: The air in Beijing is seriously polluted. Look! I can even see the floating dirt overhead.
Li: Yes, air pollution in China is extremely serious, especially in cities with heavy industry.
David: Isn't there any protecting measure adopted by government for the sake of people's health?
Li: There are many. But some depurating devices are not so effective. Some effective devices are so expensive that manufacturers can't even afford.
David: That's it. Then why not consider reducing some heavy industries?
Li: Pretty hard! China is a developing country and needs heavy industries to increase it's GDP.
David: How about transferring some plants to suburbs?
Li: It's a good idea! There is a low population density in suburbs so that the harm to people is also slight. However, it brings great inconvenience.
講解：
1. 對話中David和李平在討論有什么辦法能夠緩解現在城市中的空氣污染狀況。David抱怨說北京空氣污染真的很嚴重，都能看見上空飄著的浮塵。pollute是污染的意思，常用的句式就是pollute something with something，for example, Rivers are polluted with chemical waste from factories. 河流被工廠排放的化學廢料污染了。
2. 如果用到比喻當中，pollute可以表示“玷污或褻瀆某事物，破壞”，那么我們再來延伸一下，pollutant，污染物，pollution，pollute的名詞形式，污染。
3. 李平也說中國的空氣污染很嚴重，尤其是那些重工業城市，heavy industry，就是“重工業”，那么輕工業呢，就是“light industry”。David問難道政府沒有為了人們的健康而采取措施嗎？adopt表示“采取，采用”，例如：They adopted our methods. 他們采用了我們的辦法。Adopt還表示“收養”，She adopted a baby girl last year. 她去年收養了一個女嬰。
4. sake表示“為了…之好處, 出于對...的興趣, 緣故, 理由”，那么由它組成的短語for the sake of something或者for one's sake，就表示“為了…好處；為…著想”，I stopped smoking for the sake of my health.為了我的健康我戒煙了。She only did that for her own sake. 她那么做只是為了她自己。
5. sake還以用來加強語氣，表示迫切的請求 或不耐煩，例如：for God's sake 看在上帝的份上for Christ's sake 看在基督面上，看在老天面上，比如說，你正在專心讀書準備考試，但是隔壁正在開party，你就可以大喊，For God's sake, stop making the noise! I'm trying to read!
6. 政府當然會采取措施來控制空氣污染，只是很多凈化空氣的設備不是很有效，而很多工廠又支付不起效果顯著但是非常昂貴的機器設備。afford，表示“能夠提供，負擔得起”，既可以指實質性的東西，比如金錢，也可以指一些抽象的東西，比如時間、感情等等，例如：I can't afford a new car. 我買不起新車。He's so busy that he can't even afford an hour for lunch. 他太忙了，甚至抽不出一小時來吃午飯。
7. David說，既然負擔不起，就減少一些重工業好了，但是李平覺得這很難，因為中國是一個發展中國家，需要重工業來發展經濟，GDP就是國內生產總值，gross domestic product。David又建議說或者可以把一些工廠搬到郊區，那里人口密度小，空氣的污染面相對就會小一些。但是這又會帶來極大的不便。
