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新东方网为大家带来2020托福听力练习：废安非他命改变水下生态系统（下载），希望对大家有所帮助!更多内容请随时关注新东方网!
Last week, tens of thousands of gallons of sewage gushed into urban streams in Baltimore, because of leaky pipes and flooding rains. And when that happens, it's not just organic matter and microbes that get flushed into aquatic habitats. It's drug residues, too: caffeine, antihistamines, headache drugs... even amphetamines and heroin.
Researchers actually detected all those drugs a few years ago, in a survey of urban and suburban streams in Baltimore. And they wanted to see what effect illegal drugs, like amphetamines, might have on aquatic ecosystems. So they built artificial streams in the lab, stocked with insects and real creek rocks—slippery ones with biofilms of algae and bacteria growing on them. Then they doped half the streams with amphetamine residues—similar to the concentrations found in real urban streams.
After three weeks, the mix of microbial life in the amphetamine-laced streams changed significantly, compared to the untainted waters. And insects like midges emerged earlier than usual—suggesting that drug residues might be able to alter food webs underwater, and on land, too. The results appear in the journal Environmental Science and Technology.
Previous studies have shown that even treated sewage has lots of drug residues in it—because most wastewater treatment plants weren't built to filter out pharmaceuticals. One solution, the researchers say, is more up-to-date wastewater infrastructure. Think of it as preventive medicine…for the nation's aquatic life.
翻译见下页
上周，管道泄漏和暴雨导致数万加仑污水流入巴尔的摩的城市河流中。流入水生栖息地的不仅有有机物质和微生物，同时还有残留的药物：咖啡因、抗组胺剂、头痛药……甚至还有安非他命和海洛因。
实际上，研究人员在几年前对巴尔的摩的城市河流和郊区河流进行调查时，就发现了这些药物。他们想了解安非他命等非法药物对水生系统有什么影响。所以，他们在实验室里建了一个人工河流，河流里面有昆虫和真的溪岩，就是那些上面长有藻类和细菌的光滑岩石。然后他们在一半的人工河流中投放了安非他命残留物，其浓度与真正的城市河流中的浓度相似。
三个星期以后，与未受污染的河流相比，加有安非他命河流中的微生物发生了重大的变化。摇蚊等小昆虫出现的时间缩短，这表明药物残留物可能会改变水下的食物网，也可以改变陆地上的食物网。该研究结果发表在《环境科学与技术》期刊上。
此前的研究表明，经过处理的污水仍然含有大量的药物残留，这是因为大多数污水处理厂并并没有过滤药物。研究人员表示，其中一种解决方案是更新污水处理设备。就把这看作水生生物的预防药吧。
重点讲解：
1. because of 因为;由于;
例句：He had given up his job because of failing health.
由于体质衰弱他放弃了工作。
2. be similar to 相像的;相仿的;类似的;
例句：My opinions are similar to hers.
我的看法跟她的相似。
3. compared to 与…相比;和…比起来;
例句：This problem was insignificant compared to others she faced.
这一问题与她面临的其他问题比较起来算不得什么。
4. filter out 滤除;滤掉;
例句：Children should have glasses which filter out UV rays.
儿童应该戴上滤除紫外线的眼镜。
以上是新东方网为大家带来的2020托福听力练习：废安非他命改变水下生态系统（下载），希望认真积极的备考，早日取得优异的成绩。更多内容请随时关注新东方网!
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