农田与污染——波托马克河的故事(1/2)
概述：波托马克河流经大量农田，农田废物入河，带来严重污染Hints
The Potomac River
Washington
Chesapeake Bay
American Rivers President
Bob Irvin
Washington, D.C.
Don Boesch
University of Maryland Center for Environmental Science
校对：Mornight
翻译&注解：Yuki_90
组长：elftea
答疑：jackmghearthttp://t1.g.hjfile.cn/listen/201206/201206110916304212268.mp3The Potomac River is seen by hundreds of thousands each day as it flows under bridges and past memorials.It is used for recreational activities, and provides drinking water for 5 million people.
Before the Potomac reaches Washington, it runs through farmland in four states, and continues on to the Chesapeake Bay, the country's largest estuary.
All along its course, pollution undermines the river's water quality, says American Rivers President Bob Irvin.
"It flows through farmlands, where pesticides are running off from the fields, where farm waste is running into the streams. Then as it makes its way down through the urban area of Washington, D.C., we have runoff from our streets, and when it rains really hard we have raw sewage flowing into the river."
That runoff concerns Don Boesch, head of the University of Maryland Center for Environmental Science. He says it is creating dead zones where aquatic plants and marine life cannot survive.
"It's got low light penetration and sometimes lowest levels of oxygen in the water."
He says before the river can become healthier, the nutrient runoff must be controlled.
"These are good things that stimulate life in the river, but they actually are in excess, and so they cause lots of negative problems in the river."每天都有成千上万的人能看到波托马克河在大桥下和纪念碑旁流过，它被用于娱乐活动，并为五百万人提供饮用水。
在波托马克河到达华盛顿之前，它会流经四个州的农田，之后继续到国家最大的河口----切萨皮克湾。
美国河流协会主席鲍勃•欧文说，在整个流程中，污染破坏了河流的水质。
“它流经农田，那里杀虫剂会从土地流失，农场废物进而会流进溪流里。然后当它穿过华盛顿城区时，会在我们的街道上流下径流。每当下大雨的时候，就会有未经处理的污水流进河流里。”
马里兰大学环境科学中心主任唐•伯施很关心径流问题，他说径流正是在给水生植物和海洋生物创造不能得以生存的死亡区域。
“它的水中含有低水平的光透入率和含氧量。”
他说要想河流能够变得更为健康，就一定要控制养分径流。
“这些都是促进河内生物生长的有利因素，但事实上，这些营养已经过剩了，并且给河流带来了很多负面问题。”
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