江河水道中富含温室气体
文章来源:未知 文章作者:meng 发布时间:2010-12-21 03:33 字体: [ ]  进入论坛
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Nitrous oxide1(一氧化二氮) , a potent2 greenhouse gas, has increased by more than 20 percent over the last century, and nitrogen in waterways is fueling part of that growth, according to a Michigan State University study. Based on this new study, the role of rivers and streams as a source of nitrous oxide to the atmosphere now appears to be twice as high as estimated by the Intergovernmental Panel on Climate Change, according to Stephen Hamilton, a professor at MSU's Kellogg Biological Station. The study appears in the current issue of the Proceedings3 of the Academy of Sciences.

The increased production of nitrous oxide in streams can be traced to the growth of nitrogen fertilizers and the cultivation4 of crops that return nitrogen to the soil naturally, both of which have the unintended consequence of increasing nitrogen in streams. Some of the nitrogen entering streams is converted to nitrous oxide.

While many studies have focused on how agricultural soils contribute to the production of this greenhouse gas, little attention has been given to nitrous oxide originating from streams and rivers, according to the study.

Nitrous oxide exists at low levels in the atmosphere, yet is thought to be responsible for 6 percent of climate warming and also contributes to stratospheric(平流层的) ozone5 destruction. It packs a much bigger punch – on a molecular6 level – than carbon dioxide, Hamilton said.

"Nitrous oxide is the leading human-caused threat to the atmospheric7 ozone layer, which protects the earth from the sun's harmful ultraviolet radiation," said Hamilton, who works with MSU's Long-Term Ecological8 Research program. "And on a per molecule9 basis, its global warming potential is 300-fold greater than carbon dioxide."

Hamilton was part of a team of researchers led by Jake Beaulieu of the Environmental Protection Agency and formerly10 with the University of Notre Dame11. The team conducted experiments on 72 U.S. rivers and streams and ran their findings through a global river network model. They studied the production of nitrous oxide from the process of denitrification(脱氮) , in which bacteria convert nitrates(硝酸盐) to nitrogen gases.

"Even with more than 99 percent of denitrified nitrogen in streams and rivers being converted to the inert12 gas(惰性气体) , dinitrogen, river networks still contribute to at least 10 percent of global anthropogenic(人为的) nitrous oxide emissions," Hamilton said.

Reducing use of agricultural fertilizer and other sources of nitrogen are examples of how to decrease humanity's contribution to the growth of nitrous oxide produced in waterways, the study concluded.



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1 oxide K4dz8     
n.氧化物
参考例句:
  • Oxide is usually seen in our daily life.在我们的日常生活中氧化物很常见。
  • How can you get rid of this oxide coating?你们该怎样除去这些氧化皮?
2 potent C1uzk     
adj.强有力的,有权势的;有效力的
参考例句:
  • The medicine had a potent effect on your disease.这药物对你的病疗效很大。
  • We must account of his potent influence.我们必须考虑他的强有力的影响。
3 proceedings Wk2zvX     
n.进程,过程,议程;诉讼(程序);公报
参考例句:
  • He was released on bail pending committal proceedings. 他交保获释正在候审。
  • to initiate legal proceedings against sb 对某人提起诉讼
4 cultivation cnfzl     
n.耕作,培养,栽培(法),养成
参考例句:
  • The cultivation in good taste is our main objective.培养高雅情趣是我们的主要目标。
  • The land is not fertile enough to repay cultivation.这块土地不够肥沃,不值得耕种。
5 ozone omQzBE     
n.臭氧,新鲜空气
参考例句:
  • The ozone layer is a protective layer around the planet Earth.臭氧层是地球的保护层。
  • The capacity of ozone can adjust according of requirement.臭氧的产量可根据需要或调节。
6 molecular mE9xh     
adj.分子的;克分子的
参考例句:
  • The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
  • For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时,分子的碰撞就停止了。
7 atmospheric 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。
8 ecological IrRxX     
adj.生态的,生态学的
参考例句:
  • The region has been declared an ecological disaster zone.这个地区已经宣布为生态灾难区。
  • Each animal has its ecological niche.每种动物都有自己的生态位.
9 molecule Y6Tzn     
n.分子,克分子
参考例句:
  • A molecule of water is made up of two atoms of hygrogen and one atom of oxygen.一个水分子是由P妈?f婘??妈?成的。
  • This gives us the structural formula of the molecule.这种方式给出了分子的结构式。
10 formerly ni3x9     
adv.从前,以前
参考例句:
  • We now enjoy these comforts of which formerly we had only heard.我们现在享受到了过去只是听说过的那些舒适条件。
  • This boat was formerly used on the rivers of China.这船从前航行在中国内河里。
11 dame dvGzR0     
n.女士
参考例句:
  • The dame tell of her experience as a wife and mother.这位年长妇女讲了她作妻子和母亲的经验。
  • If you stick around,you'll have to marry that dame.如果再逗留多一会,你就要跟那个夫人结婚。
12 inert JbXzh     
adj.无活动能力的,惰性的;迟钝的
参考例句:
  • Inert gas studies are providing valuable information about other planets,too.对惰性气体的研究,也提供了有关其它行星的有价值的资料。
  • Elemental nitrogen is a very unreactive and inert material.元素氮是一个十分不活跃的惰性物质。
TAG标签: gas greenhouse waterways
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