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Welcome to the world of


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Welcome to the world of

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  1. Welcome to the world of pollution


  3. AIR POLLUTION ACID RAIN: As the name suggests, acid rain is just rain which is acidic. The rain becomes acidic because of gases which dissolve in the rain water to form various acids. Rain is naturally slightly acidic beacuse of the carbon dioxide dissolved in it (which comes from animals breathing), and to a lesser extent from chlorine (which is derived from the salt in the sea). This gives rain apH of around 5.0, and in some parts of the world it can be as low as 4.0 (this is typical around volcanoes, where the sulphur dioxide and hydrogen sulphide form sulphuric acid in the rain).

  4. About 70 percent of acid rain comes from sulphur dioxide (SO2), which dissolves into the water to form sulphuric acid. The rest comes from various oxides of nitrogen (mainly NO2 and NO3, collectively called NOx). (These figures are for Scandinavia - Scotland has a very similar ratio, while the north-eastern USA has 62 percent sulphuric acid, 32 percent nitric acid and 6 percent hydrochloric acid). These gases are produced almost entirely from burning fossil fuels, mainly in power satations and road transport: Acid rain causes lakes and rivers to become acidic, killing off fish - all the fish in 140 lakes in Minnesota have been killed, and the salmon and trout populations of Norway's major rivers have been severely reduced because of the increased acidity of the water. Short-term increases in acid levels kill lots of fish, but the greatest threat is from long-term increases, which stop the fish reproducing. The extra acid also frees toxic metals which were previously held in rocks, especially aluminium, which prevents fish from breathing. Single-celled plants and algae in lakes also suffer from increased acid levels, with numbers dropping off quickly once the pH goes below 5, and by the time the pH gets down to 4.5, virtually everything is dead.

  5. Rather surprisingly, the effects of acid rain on trees have overshadowed the effects on people. Many toxic metals are held in the ground in compounds. However, acid rain can break down some of these compounds, freeing the metals and washing them into water sources such as rivers. In Sweden, nearly 10,000 lakes now have such high mercury concentrations that people are advised not to eat fish caught in them. As the water becomes more acidic, it can also react with lead and copper water pipes, contaminating drinking water supplies. In Sweden, the drinking water reached a stage where it contained enough copper to turn you hair green! Slightly more worryingly, that much copper can also cause diarrhoea in young children, and can damage livers and kidneys.

  6. THE GREEN HOUSE EFFECT: The Earth is kept warm by it's atmosphere, which acts rather like a woolly coat - without it, the average surface temperature would be about -18 degrees Centigrade. Heat from the sun passes through the atmosphere, warming it up, and most of it warms the surface of the planet. As the Earth warms up, it emits heat in the form of infra-red radiation - much like a hot pan emits heat even after it's taken away from the cooker. Some of this heat is trapped by the atmosphere, but the rest escapes into space. The so-called "greenhouse gases" make the atmosphere trap more of this radiation, so it gradually warms up more than it should, like a greenhouse (although a greenhouse actually does this by stopping warm air rising and escaping from it).

  7. The Inter-Governmental Panel on Climate Change has predicted that this rise of one degree will happen by the year 2025. This could potentially cripple the North American corn belt, which produces much of the world's grain, leading to much higher food prices, and even less food for the Third World than they already have. However, it would also mean that some countries which are further north would be able to grow crops they had never been able to before, although there is less land as you move north from the corn belt. The other serious worry is that rising sea levels from the melting of the polar ice caps could severely flood many countries. A rise in sea levels of one metre, which many experts are predicting by the year 2100 (and some as soon as 2030), would flood 15 percent of Egypt, and 12 percent of Bangladesh. The Maldives in the Indian Ocean would almost completely disappear. Most of the countries which would suffer most from a rise in sea levels are the poor island states, so the islands in the Caribbean, South Pacific, Mediterranean and Indian Ocean have formed the Alliance of Small Island States, AOSIS, so they have a louder voice in internatioanl politics and can make the richer developed world listen to their problems. Closer to home, Britain would lose most of East Anglia, and to protect the coast line would cost an estimated 5 to 10 billion pounds

  8. There are some natural greenhouse gases: water vapour, nitrous oxide, carbon dioxide, methane and ozone. However, over the past fifty years, production of carbon dioxide, nitrous oxide and methane has risen sharply, and a new type of chemical - the chlorofluorocarbon, or CFC - has been introduced as a refrigerant, solvent and aerosol propellant, but it is also a very powerful greenhouse gas, because it can trap a lot of radiation - one molecule of CFC is 12,000 to 16,000 times as effective at absorbing infra-red radiation as a molecule of carbon dixide. , The carbon dioxide comes mainly from burning fossil fuels in power stations, which also causes acid rain. It is also created by living animals breathing, and is naturally converted by plants back to oxygen. However, deforestation is reducing the planet's carbon dioxide absoring capability. Nitrous oxide is a by-product of nylon production, and is also released by fertiliser use in agriculture. The extra methane is produced in coal mining, natural gas production and distribution (natural gas is methane), and waste disposal. One fifth of all methane generated by human activity comes from microbial decay of organic material in flooded rice fields.

  9. This graph shows how much each gas contributes to the greenhouse effect, taking into account how much of it there is and how much radiation it can absorb.

  10. NOISE POLLUTION Sound is such a common part of everyday life that we often overlook all that it can do. It provides enjoyment, for example through listening to music or bird-song. It allows spoken communication. It can alert or warn us, say though a door-bell, or wailing siren. In engineering it can tell us when something has slightly changed, like in a squeaking car. Yet in a modern society sound often annoys us. Many sounds are unpleasant or unwanted, and this is classed as noise. Causes of Noise Transport noise Industrial Noise Noise in the Sea Social Noise

  11. Road Noise This mainly comes from cars,buses, lorries, vans and motorbikes, and each of these makes noise in a variety of different ways. Typically the things that bother people the most are engine starting, gear changing, car stereos, brakes and tyres. Half the responsibility of keeping their vehicle quiet lies with the driver, making sure the car is in good working order, for example; that the brakes don't squeak. Also driver's must be aware that their vehicle is likely to cause a noise, and drive it in a way that reduces the annoyance to others; not racing along quiet residential roads, avoiding driving at night, unless necessary. The simple solution is to make people park their cars a few minutes walk away from residential areas, but when when you suggest this to people, it turns out that they would prefer to occasionally be disturbed by noise, rather than have to walk to their car, or the nearest bus stop. Aircraft Noise This is a major problem to those people who live near a busy commercial or military airport, but for most people aircraft noise goes unnoticed. As large planes have been changing from pure jet engines to fan-jet engines, the amount of noise they generate has been decreasing, albeit slowly as the old aircraft are only phased out after their useful life (typically 20 years).

  12. However as the planes get quieter, the airports grow, becoming more busy, and handling more planes every day. This means that while the total number of people effected slowly reduces, the remainder that can still hear it, hear more planes and are woken up more often at night. Industrial Noise Industrial noise comes from either an established factory, or by building works. As industrial noise is much more of a problem to people working in a factory, who might suffer permanent hearing damage as a result of noise, than to the general public, who report annoyance at it. Because of this most of the engineering solutions and regulations governing factory noise are to deal with the high levels inside, though this does have a benefit outside the factory. There are however, specific guidelines that the government has developed, under the guidance of engineers, to estimate the number of people likely to be affected by an industrial noise. With this tool, engineers can plan factories so they will disturb as few possible in the surrounding area. Once again the benefits of a new factory have to be weighed against the disturbance to the local inhabitants, and if necessary, offer some compensation to those effected.

  13. Rail traffic The level of noise associated with rail traffic is related to the type of engine or rolling stock used, the speed of the train and track type and condition. Major NSW population centres are served by electric trains which are generally quieter than diesel. Areas affected by freight trains often experience higher noise levels than areas affected by passenger trains. The problem of noise is compounded by the requirements of railway operations (especially night operations) and factors such as stopping patterns and topography which can lead to localised problems. Rail noise can be considerable, but generally affects a far smaller group of the population than road or aircraft noise as it is generally confined to residents living along rail lines in urban areas (ABS 1997b). While changes to locomotives and rolling stock mean that they have become quieter over the last few years, railway noise remains a problem because of longer, more frequent and faster trains and the build up of the urban environment.

  14. Ocean Noise The ocean has always been a noisy place to live. Breaking waves cause lots of noise, shrimps click their claws, surf on the beach and various fishy noises all contribute to the general hubbub. Now however, the greater amount of shipping has dramatically increased the noise in the ocean, drowning out all the natural noises. Huge engines hammer away, driving the ships across the oceans, radiating sound from their propellers and through their hulls. Through all this clamour there is one creature that really relies on hearing quiet noises across vast distances, and that creature is the whale. Whale song has been popular for several years now, but the whales have been using it much longer than that. It is widely believed that the whales use their song to communicate with each other, across hundreds of miles of ocean. With the increase in noise in the ocean people are beginning to worry that the whales won't be able to hear each other, and so will be less likely to find each other. This could effect their migration patterns, and so effect their population. As always it comes down to the engineer to improve on what has gone before. The ship owners don't want to pay a fortune to make their ships quiet for the benefit of a few fish (I know they're mammals really), so combined with government legislation, the engineers make ships that are cheaper, faster, and more efficient, while still making less noise than older ships. This keeps both the ship owners and environmentalists happy, while allowing the whales to sing in peace.

  15. Social Noise Of all sorts of noise, neighbourhood noise is the greatest source of noise nuisance and complaints. A survey carried out in the UK in 1986/87 estimated that 14% of the adult population was bothered by neighbourhood noise, compared with 11% from road traffic noise, and 7% bothered by aircraft noise. The sources of neighbourhood noise, in order of number of complaints, was Amplified music; Dogs; Domestic activities; Voices; DIY; Car repairs; with 10% complaining about something else. Engineers strive to make these complains less frequent. Often there is little engineers can do to reduce the noise at source. People are people, and will make a noise. What is done is to stop the noise, as it travels from from the source to the listener. Double glazing and better insulated walls are two low-tech solutions to the problem. Hi-tech solutions include the active control of sound: For every noise, making an anti-noise, and having the two cancel out, but active control is still to expensive and unreliable to apply to general cases, at the moment. Just remember, that for every time you hear a noise that annoys you, you might have annoyed someone else with your noise

  16. Water Pollution Water is probably one of the most important resources we have. People can survive without food for several weeks, but without water we would die in less than one week. On a slightly less dramatic note, millions of litres of water are needed every day worldwide for washing, irrigating crops, and cooling industrial processes, not to mention leisure industries such as swimming pools and watersports centres. Despite our dependence on water, we use it as a dumping ground for all sorts of waste, and do very little to protect the water supplies we have. There are several threats to our water resources. Oil spills kill thousands of seabirds and can wreck water desalination plants and industrial plants drawing their water from affected coastlines. However, oil can get into the sea from many other sources, and cause just as much damage. Poor management of existing water resources can lead to those resources running out or at least shrinking, such as the Aral Sea. More locally, the North Sea is suffering from heavy pollution. Much of the pollution in rivers and seas comes from chemicals, mainly from agriculture. Another pollution issue which is often overlooked is thermal pollution.

  17. LAND POLLUTION Whenwe hear a person describe a place as 'dirty', what usually comes to our minds is the bad condition of the place. The place, which could be your bedroom, is imagined to have clothes scattered on the floor and books unarranged on the shelf. However, in our site, we have decided to define the word 'dirty' in a more specific manner. 'Dirty' in our definition, means that there are rubbish or litter on the floor. This makes the atmosphere of that certain place unpleasant not only to the eye, but also to the mind. Land pollution is therefore the dirtying of the land. It comes about due to inconsiderate dumping of waste, littering and ineffective waste disposal methods.

  18. SOLID WASTE DISPOSAL The refuse collected in 2001 was disposed of at the incineration plants or in the sanitary landfill. The 4 incineration plants at Ulu Pandan, Tuas, Senoko and Tuas South processed a total of 2.55 million tonnes or 91.0 % of the total refuse generated in Singapore. The rest of the refuse was disposed of at Semakau Landfill.

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