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  3. Plastic Bag Pollution The use of plastic bags has increased at an alarming rate since they became popular in the 1980s. Big b

Plastic Bag Pollution The use of plastic bags has increased at an alarming rate since they became popular in the 1980s. Big b

admin2009-09-12  74
问题                                                   Plastic Bag Pollution
   The use of plastic bags has increased at an alarming rate since they became popular in the 1980s. Big black bin liners, plastic carrier bags carrying advertising logos, clear sandwich bags and a variety of other forms. They’re lightweight, handy and easily discarded. Too easily discarded. Just take a look around you. Plastic bags can be seen hanging from the branches, flying in the air, settled amongst bushes and floating on rivers. They block up drains causing water and sewage to overflow and become the breeding grounds of bacteria that cause diseases.
   Plastic bags are difficult and costly to recycle and most end up on landfill sites where they take around 300 years to decay. They break down into tiny toxic (有毒的) particles that pollute the soil and waterways and enter the food chain when animals accidentally consume them. But the problems surrounding waste plastic bags start long before they decay. Our planet is becoming increasingly endangered by our over-use of plastic bags.
   Production of Plastic Bags
   Plastic bags are made from ethylene (乙烯), a gas that is produced as a by-product of oil, gas and coal production. Ethylene is made into polymers (聚合体) -- chains of ethylene molecules -- called polyethylene. This substance, also known as polythene, is used to produce a range of items, including plastic bags.
   You have probably noticed two types of plastic shopping bags -- the lighter, filmy bags you get from supermarkets and food outlets, and the heavier bags from other retail outlets, like clothing stores. The supermarket bags are made from high density polyethylene (HDPE), while the thicker bags are made from low density polyethylene (LDPE). Unlike HDPE, LDPE can not be recycled.
   While plastic bags may not be the most high tech application of plastics technology, it is certainly one of the most prevalent. According to Clean Up Australia, Australians use in excess of 6 billion plastic bags per year. If tied together these bags would form a chain that is long enough to go around the world 37 times. More than half of these bags (3.6 billion) are made from HDPE.
   Dangers to Sea Life
   Plastic bags are now amongst the top 12 items of wastes most often found along the coastlines. Animals and sea creatures are hurt and killed every day by discarded plastic bags -- a dead turtle with a plastic bag hanging from its mouth isn’t a pleasant sight but mistaking plastic bags for food is commonplace amongst marine animals. Plastic blocks their intestines (肠道) and leads to slow starvation. Others become entangled in plastic bags and drown.
   Because plastic bags take hundreds of years to break down, every year our seas become "home" to more and more bags that find their way there through our sewers and waterways. Every bag that’s washed down a drain during rainfall ends up in the sea; every bag that’s flushed down a toilet ends up in the sea; every bag that’s blown into a river will most likely end up in the sea. One disquieting fact stemming from this is that plastic bags can become serial killers. Once an animal dies of plastic bags, it decays at a much faster rate than the bag. Once the animal has decomposed, the bag is released back into the environment more or less intact, ready to be eaten by another misguided organism. The incredibly slow rate of decay of plastic bags also means that each bag we use compounds the problem, because the bags simply accumulate.
   Pollution Taxes & Bans
   Different countries have adopted a range of approaches to discourage the use of plastic bags in an attempt to cut down on the number of bags finding their way into the environment. In South Africa for instance, where an estimated eight billion plastic bags are used annually, the government has implemented new regulations that will see only thicker, more durable plastic bags produced. As well as making them more suitable for reuse, it is hoped that the extra cost associated with their production and supply will prevent retailers giving the higher quality bags away, making their use a more expensive option for consumers.
   The use of plastic bags is being discouraged in other places such as Singapore and Taiwan, while the tax imposed on the use of plastic shopping bags in Ireland has resulted in the use of plastic shopping bags being reduced by 900/0 in just six months. Prior to the 15 euro cent per bag tax, it was estimated that 1.2 million plastic shopping bags were being handed out in Ireland per year. The money raised from the tax will be used to fund environmental initiatives.
   While anything that lowers our consumption is good, why wait until we’re hit financially before we change our habits when changes aren’t difficult to make?
   How about taking previously used bags with you next time you go to the shops? Or even better -- turn back time and do as grandma did and take a bamboo basket with you every time you go shopping. Shop-owners would rather you use their bags as they’re a convenient and cheap form of advertising, but what’s more important, shareholder profits or the environment?
   Plastic bags can be re-cycled although only about one in every 200 ever finds its way to a re- cycling unit. Find out if there’s a re-cycling bin near you and, if not, ask your local authority for one.
   Greenhouse Gases
   Some countries have introduced so-called "environmentally friendly plastic bags" that are biodegradable (可生物降解). These bags take about three years to break down into practically nothing and while that sounds like an attractive solution, the truth is that the process of breaking down these petrol-based bags causes carbon to become methane (甲烷) which is a greenhouse gas.
   It’s also possible to get "plastic" bags manufactured from corn. These break down very quickly and give off no more methane than any other corn product on landfill sites. Unfortunately, they’re more expensive to produce and few shops use them.
   Garbage Bins
   One question that’s often raised in connection with the plastic bag dilemma is what should be used to line bins if not plastic bags?
   To answer that, let’s go back in time to when plastic bags were yet to become commonplace. What did we doe.
   For one, we had far less garbage. Goods had much less packaging than is the case today so we didn’t fill our bins as quickly. Peelings, eggshells, tea bags and coffee grounds were all used as compost (肥料) for crops, as was any paper that wasn’t needed for lighting fires. What was left went into an unlined bin with anything dirty or wet being wrapped in newspaper first.
   If we choose carefully when shopping so as not to bring home more packaging than necessary -- there’s really no point in bringing it home just to throw it straight in the bin when we unpack, the amount of waste that goes into the kitchen bin will be halved, at least.
   Individual Effort
   By refusing to use plastic bags, you can make a huge difference to the pollution problem. Remember that each person uses about 83 bags a year. If there are four people in your family, that’s 332 plastic bags less every year. That’s 332 bags less that will:
   -- release toxins into the ground water from landfill sites
   -- stay in the environment for hundreds of years
   -- get into the food chain through animals
   -- waste energy during the manufacturing process
   -- kill any of the estimated 100,000 marine animals that die each year of plastic pollution
   These are all-important factors that have a profound effect on our environment and the creatures we share our planet with. Should we really put our own selfish needs before the needs of everything around us now and the lives of future generations? That’s up to you to decide.
选项 A、Y
B、N
C、NG
答案B
解析 全文主旨题。浏览各小标题可知，本文不仅分析了塑料袋的化学成分及其对环境造成的危害，还着重讨论了塑料袋污染的应对措施。
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