海洋环境是否健康与众多地球生灵的繁衍生息密切相关，近来由于各种原因，海洋中的“死区”越来越多，这样的趋势如果继续下去，海洋生灵甚至我们人类的未来都将面临灾难。 ' U% R5 b9 ^& {1 S7 J* @; f
Are there dead zones in the ocean? Find out on this Moment of Science.6 v. \6 N% q* j9 t: S0 h4 @( s
0 v8 J O6 @% J# R d Well, as if we needed one more reason to get our environmental act together, a recent U.N. report warns that the number and size of dead zones in the ocean is increasing.
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Dead zones are regions of oxygen-deprived water, where nothing can live. They’re caused by an excess of nutrients–usually nitrogen(氮)–released into the water. When sewage, farm fertilizers, and emissions from vehicles and factories get washed into the ocean, you get what experts call a “nitrogen cascade(氮容器)”. Tiny free- floating organisms known as plankton(浮游生物) feed on all that untreated nitrogen, and multiply to such an extent that they (1)deplete the oxygen supply in the water.
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8 ~) K, y- w0 m6 D* |$ B While fish may be able to swim away and avoid (2)suffocation, slower-moving and (3)bottom-dwelling creatures like lobsters(龙虾), clams(蛤蚌), and oysters(牡蛎) often can’t. Also, the ocean might be a large place, but right now there are 146 known dead zones, some of which span tens of thousands of square miles. One of the worst is where the Mississippi River (4)drains into the Gulf of Mexico, and dumps fertilizer (5)runoff from the Midwest.
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; f. T& ]! Q ?, l Oh,no.Is there anything we can do? We can reduce nitrogen emissions from cars and factories, and implement better sewage treatment. We can plant new forest and grasslands to (6)soak up extra nitrogen and keep it out of the water. And we can develop alternative energy sources(替代能源) that aren’t based on burning fossil fuels(化石燃料).
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如果我们需要一个理由一起进行环保行动，那么这个理由就是联合国最近的发布的一个报告警告说海洋死区的数量在不断增多，面积在不断增大。, s5 Z3 y ^; e& E9 B
' { \! X2 u3 P1 m 海洋死区是指海水中的氧气被消耗减少，以致没有东西能够生存。它们是由排入水中的过剩的营养物质引起的-这种物质常常是氮。当污水，农田肥料，以及车辆和工厂的排放物被冲刷入海中时，就形成了专家所谓的“氮容器”。像浮游生物这些自由浮动的微小生物就是以未经处理的氮为食。它们繁殖到了如此的程度，以致于耗尽了水中供应的氧气。/ c$ l: _0 {& |3 N8 o
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尽管鱼可以游走避免窒息，但是那些缓慢移动和底栖的生物，列如：龙虾，蛤蚌，和牡蛎却不行。或许海洋是一个广阔的地方，但是目前已知的海洋死区已有146个，其中一些跨度数万平方英里。最严重的地方之一是密西西比河流入墨西哥湾的地方，这里倾倒着从中西部流失过来的肥料。 |
发表于 2012-8-14 23:21:39
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