A The fertile land of the Nile delta is being eroded along Egypt's Mediterranean coast at an astounding rate, in some parts estimated at 100 metres per year. A.尼罗河三角洲肥沃的土地正在埃及境内地中海沿岸以惊人的速度发生水土流失。在某些地区，估计速度已经达到每年 100 米。 In the past, land scoured away from the coastline by the current of the Mediterranean Sea used to be replaced by sediment brought down to the delta by the River Nile, but this is no longer happening. 过去，被地中海水流冲刷走的土地会被尼罗河带来的淤泥取代，而现在这一过程已经停止。

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B Up to now, people have blamed this loss of delta land on the two large dams at Aswan in the south of Egypt, which hold back virtually oil of the sediment that used to flow down the river. B.目前为止，人们把三角洲的土壤流失归罪于埃及南部的两座阿斯旺大坝，因为它们拦截了过去流向尼罗河的淤泥。 Before the dams were built, the Nile Bowed freely, carrying huge quantities of sediment north from Africa's interior to be deposited on the Nile delta. 在建设水坝之前，尼罗河可以自由流淌，将非洲北部内陆地区的大量淤泥带到了 尼罗河三角洲。 This continued for 7000 years, eventually covering a region of over 22,000 square kilometres with layers of fertile silt. 这一过程延续了 7 000 年，最终形成了面积超过 22 000 平方公里的肥沃土地。 Annual flooding brought in new, nutrient-rich soil to the delta region, replacing what had been washed away by the sea, and dispensing with the need for fertilizers in Egypt’s richest food-growing area. 每年一次 的洪水会为三角洲补充富含营养物质的新土壤，这些土壤取代了被海水冲走的土壤，为埃及最富饶的食品生长区提供了天然肥料。 But when the Aswan dams were constructed in the 20th century to provide electricity and irrigation, and to protect the huge population centre of Cairo and its surrounding areas from annual flooding and drought, most of the sediment with its natural fertilizer accumulated up above the dam in the southern, upstream half of Lake Nasser, instead of passing down to the delta. 20 世纪所建的阿斯旺水坝主要用于提供电力、灌溉用水以及为人口密集 的开罗市中心及其周边地区提供保护，以免其受到每年一次的洪水和干旱的影响。但是在水坝建成 后，富含天然肥料的淤泥大部分沉积在了水坝上游，即纳萨尔湖的上游地区，而不再继续流入尼罗河三角洲。

C Now, however, there turns out to be more to the story. C.然而，现在看来，情况不仅如此。 It appears that the sediment-free water emerging from the Aswan dams picks up silt and sand as it erodes the river bed and banks on the 800-kilometre trip lo Cairo. 来自阿斯旺水坝不含淤泥的水流在流向开罗的 800 公里的路 程中也带走了一些淤泥，因为河流侵蚀了河床及河流沿岸。 Daniel Jean Stanley of the Smithsonian Institute noticed that water samples taken in Cairo, just before the river enters the delta, indicated that the river sometimes carries more than 850 grams of sediment per cubic metre of water - almost half of what it carried before the dams were built. Daniel Jean Stanley 在河流流入三角洲前的 位置采集了水样，经分析发现，河水有时包含的淤泥含量超过了 850 克／立方米，大约达到了水坝建成 前的一半。 ‘I’m ashamed to say that the significance of this didn't strike me until after I had read 50 or 60 studies,’ says Stanley in Marine Geology. “我要很惭愧地说，直到阅读了 50～60 份研究报告后才我发现这个事实的重要性。 "There is still a lot of sediment coming into the delta, but virtually no sediment comes out into the Mediterranean to replenish the coastline. 来到三角 洲的淤泥数量仍然很大，但是却没有淤泥能流入地中海填补海岸线。 So this sediment must be trapped on the delta itself.’ 所以这些淤泥一定囤积在了尼罗 河三角洲内部。”

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D Once north of Cairo, most of the Nile water is diverted into more than 10,000 kilometres of irrigation canals and only a small proportion reaches the sea directly through the rivers in the delta. D.一度位于开罗以北的尼罗河水，现在大都流入了长度超过 10 000 公里的灌溉水渠中，只有一小 部分能穿过三角洲中的河流最终流入大海。 The water in the irrigation canals is still or very slow-moving and thus cannot carry sediment, Stanley explains. 灌溉水渠中的水几乎不流动或者流动非常缓慢，因此无法 带走淤泥，Standley 如此解释道。 The sediment sinks to the bottom of the canals and then is added to fields by farmers or pumped with the water into the four large freshwater lagoons that are located near the outer edges of the delta. 淤泥沉到了水渠底部，随后被农民填充到了田地中，或者被与水一起 泵入了位于三角洲边缘地区的四个大型淡水泻湖中。 So very little of it actually reaches the coastline to replace what is being washed away by the Mediterranean currents. 所以，很少有淤泥能够到达海岸线用以填补被地 中海水流冲刷走的土壤。

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E The farms on the delta plains and fishing and aquaculture in the lagoons account for much of Egypt's food supply. E. 三角洲平原上的农业以及泻湖地区的渔业和水产业为埃及提供了大量食物供给。 But by the time the sediment has come to rest in the fields and lagoons it is laden with municipal, industrial and agricultural waste from the Cairo region, which is home to more than 40 million people. 但是在淤泥来 到田地和泻湖之前，就已经充满了来自开罗地区的各种生活、工业和农业垃圾，因为开罗地区人口已 达 4 000 万。 Pollutants are building up faster and faster,’ says Stanley. “污染积累的速度越来越快，”Stanley 说。 Based on his investigations of sediment from the delta lagoons, Frederic Siegel of George Washington University concurs. 基于对三角洲泻湖淤泥的分析，华盛顿大学的 Frederic Siegel 对Stanley 的说法表示赞同。 ’ In Manzalah Lagoon, for example, the increase in mercury, lead and zinc coincided with the building of the High Dam at Aswan, the availability of cheap electricity, and the development of major power-based industries,’ he says. 他说：“以Manzalah泻湖为例，随着阿斯旺高坝的建设、廉价电力的使用和大型耗电工业的发展，湖中汞、铅、铜和锌的含量也增多了。” Since that time the concentration of mercury has increased significantly. 从那时起，汞的浓度便大幅上升。 Lead from engines that use leaded fuels and from other industrial sources has also increased dramatically. 使用含铅燃料的发动机产生的铅和其他工业源产生的铅也大幅度增加。 These poisons can easily enter the food chain, affecting the productivity of fishing and farming. 这些有害物质很容易就会进入到食物链中，从而影响渔业和农业的产量。 Another problem is that agricultural wastes include fertilizers which stimulate increases in plant growth in the lagoons and upset the ecology of the area, with serious effects on the fishing industry. 另一个问题就是包括化肥（残留物）在内的农业废弃物会刺激泻湖中植物的迅速生长，扰乱该地区的生态平衡，进而对渔业产生严重的影响。

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F According to Siegel, international environmental organisations are beginning to pay closer attention to the region, partly because of the problems of erosion and pollution of the Nile delta, but principally because they fear the impact this situation could have on the whole Mediterranean coastal ecosystem. F. Siegel 说，国际环境组织已经开始密切关注这一地区，尼罗河三角洲的水土流失和污染问题是 原因之一，但更主要的原因是他们担心这种情况会对整个地中海沿岸的生态系统造成破坏。 But there are no easy solutions. 但是解决 这一问题并非易事。 In the immediate future, Stanley believes that one solution would be to make artificial floods to flush out the delta waterways, in the same way that natural floods did before the construction of the dams. Stanley 认为，可以立刻操作的一种方案是利用人工洪水将三角洲的水流通道冲 开，就像建水坝前的自然洪水的作用一样。 He says, however, that in the long term an alternative process such as desalination may have to be used to increase the amount of water available. 然而，从长远来看，可能必须要采取一些方法来增加可用淡水的数量，如海水淡化等。 ‘In my view, Egypt must devise a way to have more water running through the river and the delta,’ says Stanley. “在我看来，埃及必须想办法使更多的水流入尼罗河和三角洲”，Stanley 说。 Easier said than done in a desert region with a rapidly growing population. 然而这对于人口快速增长的沙漠地区而言，显然是说起来容易做起来难。