60秒学美语：Sunlight Activates Smog-Causing Chemicals in City Grime

学更多地道英语口语，关注公众微信【英语】微信号：yingyu9 ，如果想系统学习提高英语口语能力，报名吉米老师听力口语特训班，百度传课网chuanke.com 搜索：听力口语特训班，看到第一个即可报名，482个同学报名啦，100%好评哦！ Sunlight Activates Smog-Causing Chemicals in City Grime 城里的日光 In recent years big cities have seen lower rates of crime. But there’s still plenty of grime. Combustion from cars, factories and fires spews out nitrogen oxides. Those compounds react with sunlight and air to form ozone—the main ingredient in smog. And certain nitrogen oxides called nitrates—same stuff you find in fertilizer— also settle onto buildings and other city surfaces. Scientists figured that was the end of the story. 最近大城市的犯罪率已经下降了不少.但是,还是有不少尘垢.从汽车,工厂和燃烧活动喷射出的氮氧化物.这些化合物在阳光和空气的作用下, 会形成臭氧——烟雾的主要成分。而某种氮氧化物就是被称为硝酸盐的物质—— 你会发现和化肥成分相同——建筑物和其它城市地面的成分里也有。科学家们指出这就是问题所在了。 “Usually one thinks about pollutants such as nitrogen dioxide and nitrous acid as being lost from the atmosphere onto surfaces.” University of Toronto chemist Jamie Donaldson, at a meeting of the American Chemical Society in Boston on August 17th. “What we have been interested in is to see whether or not the influence of sunlight on urban grime material can in fact recycle these compounds and bring them back into active play in the atmosphere.” [D. James Donaldson et al, Composition and chemistry of urban grime: a field and laboratory study] 通常一个人能想到的污染物比如二氧化氮和亚硝酸，正从大气中流失进入建筑物表面 。多伦多大学的化学家Jamie Donaldson，在8月17日波士顿举行的美国化学协会会议上说到。 我们已经对是否日光对城市废料的作用会实际上使这些化合物再次循环并把它们送入大气中这件事儿产生兴趣， Donaldson and his team found that sunlight interacts with nitrates stuck in grime, kicking them back into the air, where they can contribute to smog. They verified that process by putting trays of glass balls—a proxy for window glass, but with more surface area—out in downtown Toronto, and Leipzig, Germany. The glass in sunny areas lost 10 percent more nitrogen compounds than did their shady counterparts. Donaldson和他的研究小组发现日光能和污垢中存在的硝酸互动，把它们 弄回大气中，并在那里形成烟雾。他们通过装在盘子里的玻璃球验证了这个过程，盘子里的玻璃球模拟窗户玻璃但表面积更大——玻璃球被放在了多伦多市中心的户外，以及德国莱比锡的户外。被放在阳光下的玻璃比阴暗处的玻璃多减少了10%的含氮化合物。 “The total amount of nitrogen oxides entering a city is probably well captured in models. What is not well captured is the fact that the losses are less than people had considered because a loss from the gas phase to the grime surface does not constitute a permanent loss.” 进入城市的氮氧化物总量或许在模型中可以被很好的捕获到。我们不能很好的捕捉到信息的是这些损失比人们想象的要少很多，因为从气相到污染表面的元素损失 并不属于永久损失。 So grime is not as inert as we thought it was. And city beautification efforts, aimed at making buildings more pleasing to the eye, might also make the urban environment more pleasant for the lungs. 所以，污垢并不是像我们认为的那样有惰性不活泼的物质。美化城市的工作，目的在于是建筑物更养眼 ，也许也能使城市环境更养肺。 —Christopher Intagliata