慶應SFC 2009年 環境情報学部 英語 大問1 全文

 If Bangladesh were to count her blessings, they would number three: the Brahmaputra, the Meghan and the mighty Ganges.  These great rivers are practically Bangladesh’s only natural resources. In a predominately rural country in which agriculture and freshwater fishing are the keys to the economy, the rivers are the people’s lifeblood.

 But these blessings, allied with the regions summer monsoon climate, are also a curse. Although almost two meters of rain fall on Bangladesh each year, more than two thirds [1] (1. go in 2. get in 3. arrive in) just four months.  For much of the year, the vast delta formed by the three rivers is parched, but in many summers their banks burst, causing massive floods.  Lacking proper sanitation and water storage facilities, Bangladesh is also [2] (1. prone to 2. immune to 3. adapted to) epidemics of waterborne disease. Even during floods, the major problem is the availability of safe water.

 Climate change will only make matters worse, with shifting patterns of rainfall and rising sea levels threatening to render large tracts of agricultural land [3] (1. infeasible 2. insignificant 3. useless). Add a cruel and recently discovered twist the poisoning of many millions of people by well water contaminated with arsenic and it’s clear that Bangladesh represents a challenging case study for anyone who wants to solve the world’s water problems.

 “Nowhere is water more dominant in people’s lives,” says British geographer John Soussan. And nowhere better illustrates the complexity of producing [4] (1. visible 2. subjective 3.workable) solutions to water resource problems.  The threats that face Bangladesh’s supplies are intimately interconnected: thwart one, [5] (1. and 2.or 3. for) you can create problems downstream―sometimes literally.

 Worse still, the issues are overlaid by fractious regional politics.  For decades, Bangladesh has been [6](1. in harmony with 2. in dispute with 3. in correspondence with) its neighbours ― particularly India―  over their management of the rivers that drain into Bangladeshi territory. For the country’s politicians, water is the defining issue, and the Ganges ― known in Bangladesh as the Padma ― whose basin is home to some 400 million people, is a perennial bone of contention. Despite some progress in reaching agreement over the river’s management, Bangladesh still blames India for [7](1. holding back 2. taking back 3. giving back) too much water in the dry season, and letting the floodgates open each time the monsoon threatens.

 The picture looks bleak, but experts point out that Bangladesh is, in some ways, a victim of its own success. Given the hydrological hand they were dealt, the inhabitants of the Bengal Delta traditionally grew low-yielding but flood tolerant rice, and fished wetlands and pools that were recharged by annual floods. This could support a modest population at [8](1. Flat 2. Similar 3. Subsistence) levels, but no more. Since the late 1950s, however, aid­donor-backed irrigation schemes, later incorporating groundwater pumping, have opened up vast areas of fertile delta soil to the plough.  Now almost all of the land in Bangladesh that is suitable for agriculture is in use. High-yielding rice varieties have boosted productivity hugely, while the development of coastal areas for shrimp farming has also provided further food and revenue.

 As a result, the population has quadrupled since 1950. Today, an average of 920 people crowd into each square kilometer of Bangladesh, making it one of the most [9](1. largely 2. densely 3. appropriately) populated countries in the world. Therein lies the problem: population pressure has helped to make droughts more severe and floods potentially more [10](1. devastating 2. demanding 3. enriching). Also, with sanitation still inadequate, the rapid population growth of the past half century has exacerbated problems with waterborne disease.  Environmental scientist Atiq Rahman [11](1. prefers 2. likens 3. ascribes) Bangladesh to a giant toilet flushed just once a year.

 By the 1970s, it was clear that something had to be done, and aid agencies ― led by the World Bank and UNICEF ― [12] ( 1. caught up with 2. hit on 3. got away with) the idea of sinking tube wells into the underground water reservoirs that lie beneath the deltas surface. Local people, [13](1. dependent on 2. fearful of 3. indifferent to) this subterranean source, initially called it the Devils water.” But when rates of diarrheal disease halved, the programmer was deemed an unqualified success. By the 1990s, as many as 10 million wells had been sunk, many of them by local companies.

 If only things were that simple: the tragedy that has subsequently unfolded reveals in stark terms how “solutions” to water resource problems can go astray if our knowledge of a region’s hydrology and geology is [14] (1. incomplete 2. sufficient 3. accumulated). It was Dipankar Chakraborty, an epidemiologist, who first raised the alarm. In 1988, on a visit to his Bengali parents’ rural village, Chakraborty noticed that many local people were suffering from skin lesions and cancers that seemed to be [15] (1. independent of 2. causing 3. consistent with) arsenic poisoning. When he tested samples of well water in his laboratory at Jabalpur University in Calcutta, it became clear why: the villagers’ water supply was massively tainted with the metal.

 Over the ensuing five years, Chakraborty and his colleagues at Dhaka Community Hospital showed that the problem extends across large areas of the Bengal Delta on both sides of the India-Bangladesh border.  Some wells contain 400 times the World Health Organization (WHO) safe drinking water standard for arsenic. Current estimates are that 80 million Bangladeshis are [16] ( 1. at large 2. at odds 3. at risk), with 30 million drinking water containing five times the WHO arsenic limit. “The danger is very, very real,” says Chakraborty.

 The arsenic was washed from the sediments of the Himalayas, and is thought to have been accumulating beneath the Bengal Delta for at least 2 million years. The puzzle is why it is now being drawn to the surface in some wells, but not in others. One leading theory is that the arsenic is released from the sediments into groundwater under oxygen-free, reducing conditions. And some researchers suspect that rotting vegetation in the uppermost 30 meters or so of sediment creates just such an environment.  That would help to explain why the problem seems worse in shallower wells, and adds to hopes that it may be possible to [17] (1. modify 2. identify. overcome) and selectively shut down those that are hazardous.

 But recent research from a team led by Shaniqua Islam, a Bangladeshi hydrologist, suggests that the pumping of groundwater for irrigation seems to be drawing arsenic into deeper wells. The mechanism remains [18] (1. unclear 2. transparent 3. simple, but Islam suspects that deep groundwater is being replaced by surface water that is rich in organic material, which then mobilizes previously insoluble arsenic. Chakraborty has also found that wells that his group tested and marked as safe had become dangerous when surveyed again a few years later.

1 What’s more, drinking water may not be the only hazard: rice crops irrigated with arsenic contaminated groundwater have now been shown to accumulate the toxic element. Although its [19] (1. too easy 2. too late 3. too early) to tell whether this poses a serious threat, the finding has sown seeds of doubt about the use of groundwater for irrigation, which is the mainstay of Bangladesh’s agriculture.

 Research and new technology will be central to [20](1. undermining 2. tackling 3. indicating) the arsenic problem. Surveying and screening wells is a top priority, yet arsenic testing kits for use in the field are still unreliable. More work is also needed to confirm the conditions under which arsenic is mobilized from the sediments, and at what depths this occurs.

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