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  3. Global Water Problem The UN’s World Summit on Sustainable Development to be held in Johannesburg from August 26 to September

Global Water Problem The UN’s World Summit on Sustainable Development to be held in Johannesburg from August 26 to September

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问题                             Global Water Problem
    The UN’s World Summit on Sustainable Development to be held in Johannesburg from August 26 to September 4 is supposed to result in plans to reduce global poverty and the North-South income gap without causing irreparable damage to the environment. As a follow up to the Earth Summit of 1992, it is using the Millennium Development Goals (MDG) as a guide.    These are part of the UN’s 2000 Millennium Declaration, which resolved to cut the proportion of people who are unable to get safe drinking water in half by 2015.
    Following are some facts and figures on the state of the world’s water supplies and the UN’s goals regarding water.
Water Supply and Shortage
    A new study warns that about thirty percent of the world’s people may not have enough water by the year 2025.    A private American organization called Population Action International did the new study. It says more than three hundred-thirty-five-million people lack enough water now. The people live in twenty-eight countries which are mostly in Africa or the Middle East.
    PAI researcher Robert Engelman says by the year 2025 about three billion people may lack water. At least 18 more countries are expected to have severe water problems. The demand for water keeps increasing. Yet the amount of water on Earth stays the same.
    Mr. Engelman says the population in countries that lack water is growing faster than in other parts of the world. He says population growth in these countries will continue to increase.
    Freshwater ecosystems cover less than 1 percent of the Earth’s surface. Ice    mostly in the form of glacier    comprises 69 percent of the world’s freshwater supplies and groundwater is 30 percent. Wetlands, which include marshes and swamps, comprise 0. 3 percent, lakes 0.3 percent, and rivers 0.06 percent. However, many experts argue that the world’s wells are not about to run dry.
    They say that on a global level we have enough water but must use it more wisely and attempt to address uneven distribution around the globe which is related partly to different rainfall patterns.
    Problem/Issue
    Lacking of water in the future may result in several problems. It may increase health problems. Lack of water often means drinking water is not safe. Mr. Engelman says there are problems all over the world because of diseases, such as cholera (霍乱), which are carried in water. Lack of water may also result in more international conflicts.    Countries may have to compete for water in the future. Some countries now get sixty percent of their fresh water from other countries. This is true of Egypt, the Netherlands, Cambodia, Syria, Sudan, and Iraq. Water shortage would affect the ability of developing to improve their economies. This is because new industries often need a large amount of water when they are beginning.
    Moreover, there are many problems with the world’s fresh water supplies, including pollution from industry, agriculture and untreated sewage. The World Bank says inefficient infrastructure means that water that does not reach customers is not only wasted but ultimately not paid for. This can lead to infrastructure decay because of a lack of funding for maintenance. Tariffs are often kept low by politicians seeking to woo voters, leading many to advocate the privatization of water services-95 percent of municipal water services are publicly run    but this is controversial because of concerns that the very poor could be denied access. Privatization advocates argue that services will improve at a lower cost as a result because the contracted operators will have an incentive (动机) to improve their product.
    Dams
    Dams have brought huge benefits to more than 140 countries but the social and environmental costs have often been high. Perhaps 40 to 80 million people have been displaced globally by dam projects. Dams have damaged aquatic habitats and blocked migration routes. According to a 2000 report by the World Commission on Dams, China and India have half of the world’s 45,000 dams. Dams account for only 19 percent of electricity generated worldwide, but 24 countries generate more than 90 percent of their power from dams.
Species at Risk
    According to the WWF (World Wildlife Fund), of 10,000 species of freshwater fish, 20 percent are threatened by pollution, habitat destruction, damming, over-fishing and the introduction or invasion of alien species. The WWF says that 81 freshwater fish species have become extinct over the past century. The major proportion of known extinctions resulted from the introduction of the huge Nile perch (河鲈) in Africa’s Lake Victoria, which caused the loss of 50 species. But scientists say the state of knowledge about freshwater fish is incomplete so many unknown to us may have become extinct already.
    In addition to fish, the WWF says that four of the five species of river dolphin, two of the three manatee species, about 40 freshwater turtles and more than 400 types of freshwater crustaceans are at risk.
    An Example of Misuse
    The land-locked Aral Sea (咸海), which straddles (跨) the former Soviet Central Asian republics of Uzbekistan and Kazakhstan, is actually salt, but its tragedy highlights the potentially disastrous consequences of poor freshwater use. In the 1960s, Soviet planners built a network of canal to divert the waters of the river that fed the sea to irrigate cotton fields in Uzbekistan and Turkmenistan. As a result, the sea’s life source was reduced to a trickle, and it is shrinking and dying as a result. Once the world’s fourth largest lake, the Aral Sea has shrunk so much that it is now split. into two separate bodies of water-the northern or little Aral Sea and a larger southern body. Aralsk, once a thriving port town, is now 95 kilometers front the coast.
Tackling the Water Problem
    The Population Action International study gives several solutions to the water problem. One way, it says, is to find ways to use water for more than one purpose. Another way is to teach people to be careful not to waste water. A third way is to use less water of agriculture. The report also says long term solutions to the water problem must include controls on population growth.    It says countries cannot provide clean water unless they slow population growth by limiting the number of children people have.
The main reason for the reduction of the species of freshwater fish is ______.
选项
答案introduction of a huge Nile perch
解析 第十一段主要谈论的是濒危物种以及灭绝的原因。"The major proportion of known extinctions  resulted from the introduction of the huge Nile perch in Africa’s Lake Victoria，"表明大部分淡水鱼类的最大威胁是引进了一种来自非洲尼罗河的河鲈，当然这也是淡水鱼类数量、种类急剧减少的最主要原因。
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