評(píng)論
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If you've ever seen movies about World War I, you know thatthe soldiers in the trenches often wore bulbous gas masks that made them look like human insects.
如果你看過(guò)關(guān)于一戰(zhàn)的電影的話，你肯定知道沖在一線的士兵們通常會(huì)配戴著球莖形狀的防毒面罩，看起來(lái)很像人形昆蟲(chóng)。
The masks were necessary to protect them from chemical weapons such as chlorine gas, a noxious substance that could almost instantly suffocate unprotected victims.
這種面具可以保護(hù)士兵不被化學(xué)武器攻擊，如氯氣-一種可以快速使人窒息的有毒氣體。
If chlorine is so dangerous, why the do we dump it in swimming pools?
如果氯算危險(xiǎn)物質(zhì)的話，那么為什么我們要把它倒進(jìn)游泳池里呢？
As you probably already know, chlorine is used to disinfect swimming pools.
你可能已經(jīng)知道，氯可以用于消毒游泳池。
It also gives mostpools their distinctive odor.
同時(shí)，大多數(shù)加氯的游泳池也會(huì)有一種獨(dú)特的味道。
Chlorine comes in pellet, liquid, and gas forms, and when it reacts withpool water it immediately breaks down into different chemicals, including hypochlorous acid and hypochlorite ion.
氯可以以固、液、氣三種形式存在。氯遇到水會(huì)立刻分解成不同的化學(xué)物質(zhì)，如：次氯酸和次氯酸鹽離子。
Both chemicals attack micro organisms in the water by breaking through their cellwalls and scrambling the inner workings of the cells, rendering them harmless.
這兩種化學(xué)物質(zhì)都可以通過(guò)破壞水中微生物的細(xì)胞壁、擾亂細(xì)胞內(nèi)部正常運(yùn)轉(zhuǎn)而使微生物變的無(wú)害。
So why don't these killer chemicals destroy human cells as well?
那這些致命的化學(xué)物質(zhì)不會(huì)破壞人體細(xì)胞呢？
They would, if not for the verysmall amounts of chlorine needed to cleanse the typical pool.
如果用于清理泳池的氯使用量過(guò)大的話是會(huì)對(duì)人體造成傷害的。
For example, the concentration of chlorine used to sanitize an Olympic-size pool is three parts per million, meaning that for everythree molecules of chlorine there are one million water molecules.
比如，用于奧運(yùn)會(huì)的泳池消毒的氯濃度是3比100萬(wàn)，也就是說(shuō)每一百萬(wàn)個(gè)水分子里有三個(gè)氯分子。
Such low concentrations may cause slight irritation to the eyes and skin, but there's not enough chlorine to cause any real harm to swimmers.
這樣的低濃度可能只會(huì)對(duì)眼睛和皮膚產(chǎn)生輕微刺激，但對(duì)游泳的人來(lái)說(shuō)不會(huì)產(chǎn)生真正的傷害。
Chlorine is not the only chemical used to keep pools clean—bromine and ozone are becoming increasingly popular in pool maintenance facilities.
氯不是唯一能夠保持泳池清潔的化學(xué)物質(zhì)-溴和臭氧在泳池的日常維護(hù)中也越加頻繁。
But chlorine is still the pool cleaner's mainstay.
但泳池清潔人員主要還是用氯來(lái)消毒。
