VOA慢速英語:研究：密西西比河因大量農(nóng)藥的使用而不堪重負

研究：密西西比河因農(nóng)藥的大量使用而不堪重負

From VOA Learning English, this is the Agriculture Report.

這里是美國之音慢速英語農(nóng)業(yè)報道。

An area known as a dead zone develops every spring in the Gulf of Mexico near the mouth of the Mississippi River. It can spread as much as 13,600 square kilometers, extending all the way to the eastern Texas coast. Scientists know what causes the dead zone -- too much nitrogen, but the solution might be hard to accept.

在墨西哥灣靠近密西西比河河口的地方，每年春天都會變成死水區(qū)。它可以蔓延13600平方公里，可以一直蔓延到德克薩斯州東部海岸?？茖W家知道這片死水區(qū)是怎樣來的——是因為里面有太多的化學元素氮，但是解決方法可能也很難接受。

Bayani Cardenas is a professor of water studies at the University of Texas at Austin. He says the movement of rivers usually removes material like nitrates. So he wondered why that natural filtration process does not remove nitrates from the Mississippi River.

巴亞妮·卡迪納斯是奧斯丁德克薩斯大學研究水的教授，他稱河流的運動經(jīng)常會清除一些像硝酸鹽類的物質(zhì)。所以他很好奇為什么自然過濾不能清除密西西比河里的硝酸鹽。

Professor Cardenas says his recent study shows that more than 99 percent of the river's water does pass through the river's sediment which is on the shore or bottom of the river. But he says the study found that there is so much nitrogen in the river system that is simply can not filter all of it.

卡迪納斯教授稱，他最近的研究表明，多于99%的河水流經(jīng)岸邊或河底的沉淀物。但是他稱研究發(fā)現(xiàn)在這條河里有太多氮，這并不是很簡單就可以過濾掉的。

The water that has nitrogen still in it supports the growth of algae. As the algae dies, it sinks to the bottom of the river where it breaks down or decomposes. It then takes oxygen from the water. This condition is called hypoxia and it is deadly to fish and shrimp.

含氮的河水也會促進藻類的生長，隨著藻類的死亡，這些藻類就會沉淀到河底，然后分解，這樣就會消耗掉水里的氧氣。這種環(huán)境狀況叫做缺氧，這對于魚蝦來說是致命的。

Where does all this nitrogen come from? The answer is farms. The Mississippi River system carries water from 33 American states and part of Canada to the gulf of Mexico. Along the way nitrogen and other chemicals used in farming enter the system. Farmers say these chemicals must be used to produce enough food for a growing world population.

這些氮來自哪呢?答案是農(nóng)場。密西西比河流經(jīng)美國33個州，還有加拿大到墨西哥灣的部分地區(qū)。流經(jīng)沿途中，農(nóng)業(yè)種植中所用的氮和其他化學成分就會流入河中。農(nóng)民們稱，隨著世界人口的不斷增長，這些農(nóng)藥必須用于農(nóng)業(yè)種植來獲得足夠的食物。

Aaron Packman is a professor of Civil and Environmental Engineering at Northwestern University. He says farmers may be able to better control the amount of nitrate fertilizer they put on fields.

亞倫·帕克曼是美國西北大學土木與環(huán)境工程系的教授，他稱農(nóng)民可能有能力更好的控制天地中硝態(tài)氮肥的使用量。

"How much fertilizer do you need to give you good yields and then how much is maybe a marginal gain from adding lots more fertilizer? There is really a question here: can you maybe [reduce the amount] and get close to the same level of yield without having such a negative impact?" said Packman.

帕克曼說：“你需要使用多少肥料才可以有你好的收成，還有使用大量肥料最多可以獲得多少收成?這真是一個問題，或許你減少次肥料的用量也可以獲得接近于你想要的收成量，從而又消除了對河流的不良影響呢?”

The water in the Mississippi River system should be able to clean itself naturally as it flows down stream. But flood controls and other human-made structures have hurt this filtering process.

因為密西西比河的水向下流動，它本應該可以自然的凈化自己。但是，防洪控制和其他認為建造嚴重影響了其自濾過程。

Storms in the next few month will mix the gulf water and the dead zone will disappear, but it will return next year. And scientists say it will grow larger in years to come, if something is not done to reduce the amount of nitrogen in the Mississippi River.

幾個月以后的暴風雨將會混合海灣里的水，那時死水區(qū)將會消失，但是明年它還會形成。并且科學家稱，如果在未來幾年不能減少密西西比河里的氮含量，這片死水區(qū)會變得越來越大。

And that's the VOA Learning English Agriculture Report. I'm Caty Weaver.

這就是本期美國之音慢速英語農(nóng)業(yè)報道的全部內(nèi)容，我是卡蒂·韋弗。