海洋的演变史及堪忧的未来
文章来源:未知 文章作者:enread 发布时间:2013-06-16 01:29 字体: [ ]  进入论坛
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The ocean the Titanic1 sailed through just over 100 years ago was very different from the one we swim in today. Global warming is increasing ocean temperatures and harming marine2 food webs. Nitrogen run-off from fertilizers is causing coastal3 dead zones. A McGill-led international research team has now completed the first global study of changes that occurred in a crucial component4 of ocean chemistry, the nitrogen cycle, at the end of the last ice age. The results of their study confirm that oceans are good at balancing the nitrogen cycle on a global scale. But the data also shows that it is a slow process that may take many centuries, or even millennia5, raising worries about the effects of the scale and speed of current changes in the ocean. "For the first time we can quantify how oceans responded to slow, natural climate warming as the world emerged from the last ice age," says Prof. Eric Galbraith from McGill University's Department of Earth and Oceanic Sciences, who led the study. "And what is clear is that there is a strong climate sensitivity in the ocean nitrogen cycle."
 
The nitrogen cycle is a key component of the global ocean metabolism6(新陈代谢). Like the proteins that are essential to human health, nitrogen is crucial to the health of oceans. And just as proteins are carried by the blood and circulate through the body, the nitrogen in the ocean is kept in balance by marine bacteria through a complicated cycle that keeps the ocean healthy. The phytoplankton(浮游植物) (microscopic organisms at the base of the food chain) 'fix' nitrogen in the shallow, sunlit waters of the ocean, and then as they die and sink, nitrogen is eliminated (a process known as 'denitrification') in dark, oxygen-poor pockets of the ocean depths.
 
Using sediment7 gathered from the ocean floor in different areas of the world, the researchers were able to confirm that as the ice sheets started melting and the climate warmed up at the end of the last ice age, 18,000 years ago, the marine nitrogen cycle started to accelerate. The ocean had stabilized8 itself in its new, warmer state, in which the overall nitrogen cycle was running faster, by about 8,000 years ago. Given the current dramatic rate of change in the ocean nitrogen cycle the researchers are not sure how long it will take for marine ecosystems9 to adapt.
 
"We are changing the planet in ways we are not even aware of," says Galbraith. "You wouldn't think that putting carbon dioxide into the atmosphere would change the amount of nitrogen available to fish in the ocean, but it clearly does. It is important to realize just how interconnected everything is."
 
This research was funded by: the Canadian Institute for Advanced Research (CIFAR) through the Earth System Evolution Program


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1 titanic NoJwR     
adj.巨人的,庞大的,强大的
参考例句:
  • We have been making titanic effort to achieve our purpose.我们一直在作极大的努力,以达到我们的目的。
  • The island was created by titanic powers and they are still at work today.台湾岛是由一个至今仍然在运作的巨大力量塑造出来的。
2 marine 77Izo     
adj.海的;海生的;航海的;海事的;n.水兵
参考例句:
  • Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
  • When the war broke out,he volunteered for the Marine Corps.战争爆发时,他自愿参加了海军陆战队。
3 coastal WWiyh     
adj.海岸的,沿海的,沿岸的
参考例句:
  • The ocean waves are slowly eating away the coastal rocks.大海的波浪慢慢地侵蚀着岸边的岩石。
  • This country will fortify the coastal areas.该国将加强沿海地区的防御。
4 component epSzv     
n.组成部分,成分,元件;adj.组成的,合成的
参考例句:
  • Each component is carefully checked before assembly.每个零件在装配前都经过仔细检查。
  • Blade and handle are the component parts of a knife.刀身和刀柄是一把刀的组成部分。
5 millennia 3DHxf     
n.一千年,千禧年
参考例句:
  • For two millennia, exogamy was a major transgression for Jews. 两千年来,异族通婚一直是犹太人的一大禁忌。
  • In the course of millennia, the dinosaurs died out. 在几千年的时间里,恐龙逐渐死绝了。
6 metabolism 171zC     
n.新陈代谢
参考例句:
  • After years of dieting,Carol's metabolism was completely out of whack.经过数年的节食,卡罗尔的新陈代谢完全紊乱了。
  • All living matter undergoes a process of metabolism.生物都有新陈代谢。
7 sediment IsByK     
n.沉淀,沉渣,沉积(物)
参考例句:
  • The sediment settled and the water was clear.杂质沉淀后,水变清了。
  • Sediment begins to choke the channel's opening.沉积物开始淤塞河道口。
8 stabilized 02f3efdac3635abcf70576f3b5d20e56     
v.(使)稳定, (使)稳固( stabilize的过去式和过去分词 )
参考例句:
  • The patient's condition stabilized. 患者的病情稳定下来。
  • His blood pressure has stabilized. 他的血压已经稳定下来了。 来自《现代英汉综合大词典》
9 ecosystems 94cb0e40a815bea1157ac8aab9a5380d     
n.生态系统( ecosystem的名词复数 )
参考例句:
  • There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
  • Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样,从雨林到半荒漠等不一而足。 来自辞典例句
TAG标签: ocean global nitrogen
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