科学家揭示地球早期大气组成-凯发k8官网

科学家揭示地球早期大气组成
文章来源:未知 文章作者:enread 发布时间:2011-12-01 06:07 字体: [ ] 
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scientists in the new york center for astrobiology(天体生物学) at rensselaer 1 institute have used the oldest minerals on earth to reconstruct the 2 conditions present on earth very soon after its birth. the findings, which appear in the dec. 1 edition of the journal nature, are the first direct evidence of what the ancient atmosphere of the planet was like soon after its formation and directly challenge years of research on the type of atmosphere out of which life arose on the planet. the scientists show that the atmosphere of earth just 500 million years after its creation was not a 3(甲烷) -filled wasteland as 4 proposed, but instead was much closer to the conditions of our current atmosphere. the findings, in a paper titled "the oxidation state(氧化态) of hadean magmas and implications for early earth's atmosphere," have implications for our understanding of how and when life began on this planet and could begin elsewhere in the universe.

for decades, scientists believed that the atmosphere of early earth was highly reduced, meaning that oxygen was greatly limited. such oxygen-poor conditions would have resulted in an atmosphere filled with 5(有害的) methane, carbon monoxide(一氧化碳) , hydrogen sulfide, and ammonia. to date, there remain widely held theories and studies of how life on earth may have been built out of this deadly atmosphere 6.

now, scientists at rensselaer are turning these atmospheric assumptions on their heads with findings that prove the conditions on early earth were simply not 7 to the formation of this type of atmosphere, but rather to an atmosphere dominated by the more oxygen-rich compounds found within our current atmosphere -- including water, carbon dioxide, and 8 dioxide.

"we can now say with some certainty that many scientists studying the origins of life on earth simply picked the wrong atmosphere," said bruce watson, institute professor of science at rensselaer.

the findings rest on the widely held theory that earth's atmosphere was formed by gases released from 9 activity on its surface. today, as during the earliest days of the earth, magma flowing from deep in the earth contains dissolved gases. when that magma nears the surface, those gases are released into the surrounding air.



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1 g1vzw     
adj.各种工艺的,综合技术的;n.工艺(专科)学校;理工(专科)学校
参考例句:
  • she was trained as a teacher at manchester polytechnic.她在曼彻斯特工艺专科学校就读,准备毕业后做老师。
  • when he was 17,einstein entered the polytechnic zurich,switzerland,where he studied mathematics and physics.17岁时,爱因斯坦进入了瑞士苏黎士的专科学院,学习数学和物理学。
2 6eayr     
adj.大气的,空气的;大气层的;大气所引起的
参考例句:
  • sea surface temperatures and atmospheric circulation are strongly coupled.海洋表面温度与大气环流是密切相关的。
  • clouds return radiant energy to the surface primarily via the atmospheric window.云主要通过大气窗区向地表辐射能量。
3 t1eyx     
n.甲烷,沼气
参考例句:
  • the blast was caused by pockets of methane gas that ignited.爆炸是由数袋甲烷气体着火引起的。
  • methane may have extraterrestrial significance.甲烷具有星际意义。
4 bkzzzc     
adv.以前,先前(地)
参考例句:
  • the bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
  • let me digress for a moment and explain what had happened previously.让我岔开一会儿,解释原先发生了什么。
5 zhoxb     
adj.有害的,有毒的;使道德败坏的,讨厌的
参考例句:
  • heavy industry pollutes our rivers with noxious chemicals.重工业产生的有毒化学品会污染我们的河流。
  • many household products give off noxious fumes.很多家用产品散发有害气体。
6 jw8znt     
n.鸡尾酒;餐前开胃小吃;混合物
参考例句:
  • we invited some foreign friends for a cocktail party.我们邀请了一些外国朋友参加鸡尾酒会。
  • at a cocktail party in hollywood,i was introduced to charlie chaplin.在好莱坞的一次鸡尾酒会上,人家把我介绍给查理·卓别林。
7 hppzk     
adj.有益的,有助的
参考例句:
  • this is a more conducive atmosphere for studying.这样的氛围更有利于学习。
  • exercise is conducive to good health.体育锻炼有助于增强体质。
8 ps4wc     
n.硫,硫磺(=sulphur)
参考例句:
  • sulfur emissions from steel mills become acid rain.炼钢厂排放出的硫形成了酸雨。
  • burning may produce sulfur oxides.燃烧可能会产生硫氧化物。
9 blgzq     
adj.火山的;象火山的;由火山引起的
参考例句:
  • there have been several volcanic eruptions this year.今年火山爆发了好几次。
  • volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。
tag标签: earth methane atmosphere
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