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时间:2006-04-14 16:00来源:互联网 提供网友:天心皓月   字体: [ ]


Scientists Measure Ocean Health by Its Color



You wouldn't order phytoplankton from a menu, but these microscopic1 green algae2 are an important food. They are the first link of the food chain for all marine3 life and are most abundant where fish are in great supply.


Phytoplankton is also the undersea lungs of the planet. Ocean biologist Michael Behrenfeld at the U.S. space agency, NASA, says that, like plant life on land, these single-celled floating organisms inhale4 carbon dioxide and exhale5 oxygen.


Michael Behrenfeld; Most people that I talk to are actually very surprised to hear that about half of the oxygen produced by plants on this planet actually comes from the oceans, not trees or shrubs7 or grasses. That's what is fueling our global ocean ecosystems9.


Phytoplankton also takes in about half of the carbon dioxide absorbed from the atmosphere by plants. Carbon dioxide is considered a major contributor to global warming. Therefore, the vitality10 of phytoplankton is crucial to Earth's health.


Scientists have been trying to develop an accurate way to measure its abundance and growth rate since the plants were discovered more than a century ago. A traditional technique measured just the variations in the green color reflected up to satellite cameras by the chemical chlorophyl in phytoplankton. Mr. Behrenfeld says the problem is that no one knows how well the color of the chlorophyl, which can vary based on temperature and the amount of nutrients11 and light, relates to phytoplankton's volume, or biomass.


The new method Mr. Behrenfeld and his associates developed uses a complex mathematical formula to compare the chlorophyl color to the amount of carbon in the phytoplankton. Carbon is a better predictor for biomass. They are also getting a truer measure of the greenness of the chlorophyl by assessing not only its hue12 but also brightness, and by correcting for the brighter light bouncing back from land and the atmosphere.


Michael Behrenfeld: We can now determine actually how green the individual phytoplankton are from space. And from years and years of laboratory studies, we know that the greenness of the cells provides a fingerprint13 to growth rate. So that's what we're doing. We're getting the greenness of the cells as well as the biomass, and that gives us growth rate and biomass.


The NASA scientist says the two measures together provide a more accurate assessment14 of ocean quality. The increased clarity will help determine how well the oceans' organisms are holding up under stresses such as pollution and global warming. Mr. Behrenfeld says it will also contribute to improved computer models that better predict how climate change will alter the environment.


Michael Behrenfeld: One of the hopes NASA has with all the investment it is putting into Earth-observing satellites is that with this information, we will get a better understanding of how our biosphere15 functions today. If we can understand how it is working today, we hope that we can predict better how it will behave in the future.


Earlier analyses of satellite imagery showed a decline of phytoplankton over the past two decades. But co-researcher David Siegel, a geologist16 at the University of California at Santa Barbara, says the good news from the improved analytical17 method is that it shows much more of the algae in the tropics than previously18 thought.


David Siegel: The differences are 200 percent for the tropics. We are predicting much more production in the tropics by taking into account that the phytoplankton can change the amount of pigment19 per cell. So it's very exciting from the point of view of a satellite oceanographer.


However, Mr. Siegel says the previous measurement technique overestimated20 how much phytoplankton production occurs in cooler latitudes21.


The researchers warn that they have just begun using their new methods. They say they must collect much more satellite data before they can determine its production rate of marine plants more precisely22 to give a more accurate picture of the health of the oceans.


David McAlary, VOA news, Washington.



phytoplankton [7faitEu5plANktEn] n. 浮游植物

algae [5AldVi:] n. 藻类,海藻

organism [5C:^EnizEm] n. 生物体,有机体

carbon dioxide n. []二氧化碳

shrub6 [FrQb] n. 灌木,灌木丛

ecosystem8 [i:kE5sistEm] n. 生态系统

chlorophyl [5klCrEfil] n. 叶绿素

biomass [5baiEumAs] n. (单位面积或体积内)生物的数量

hue [hju:] n. 色调,颜色,色彩

biosphere [5baiEsfiE] n. 生物圈

pigment [5pi^mEnt] n. 色素,颜料

oceanographer [9EuFiE5nC^rEfE(r)] n. 海洋学者,海洋研究者


1 microscopic nDrxq     
  • It's impossible to read his microscopic handwriting.不可能看清他那极小的书写字迹。
  • A plant's lungs are the microscopic pores in its leaves.植物的肺就是其叶片上微细的气孔。
2 algae tK6yW     
  • Most algae live in water.多数藻类生长在水中。
  • Algae grow and spread quickly in the lake.湖中水藻滋蔓。
3 marine 77Izo     
  • 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。
4 inhale ZbJzA     
  • Don't inhale dust into your lung.别把灰尘吸进肺里。
  • They are pleased to not inhale second hand smoke.他们很高兴他们再也不会吸到二手烟了。
5 exhale Zhkzo     
  • Sweet odours exhale from flowers.花儿散发出花香。
  • Wade exhaled a cloud of smoke and coughed.韦德吐出一口烟,然后咳嗽起来。
6 shrub 7ysw5     
  • There is a small evergreen shrub on the hillside.山腰上有一小块常绿灌木丛。
  • Moving a shrub is best done in early spring.移植灌木最好是在初春的时候。
7 shrubs b480276f8eea44e011d42320b17c3619     
灌木( shrub的名词复数 )
  • The gardener spent a complete morning in trimming those two shrubs. 园丁花了整个上午的时间修剪那两处灌木林。
  • These shrubs will need more light to produce flowering shoots. 这些灌木需要更多的光照才能抽出开花的新枝。
8 ecosystem Wq4xz     
  • This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
  • We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。
9 ecosystems 94cb0e40a815bea1157ac8aab9a5380d     
n.生态系统( ecosystem的名词复数 )
  • 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
10 vitality lhAw8     
  • He came back from his holiday bursting with vitality and good health.他度假归来之后,身强体壮,充满活力。
  • He is an ambitious young man full of enthusiasm and vitality.他是个充满热情与活力的有远大抱负的青年。
11 nutrients 6a1e1ed248a3ac49744c39cc962fb607     
n.(食品或化学品)营养物,营养品( nutrient的名词复数 )
  • a lack of essential nutrients 基本营养的缺乏
  • Nutrients are absorbed into the bloodstream. 营养素被吸收进血液。 来自《简明英汉词典》
12 hue qdszS     
  • The diamond shone with every hue under the sun.金刚石在阳光下放出五颜六色的光芒。
  • The same hue will look different in different light.同一颜色在不同的光线下看起来会有所不同。
13 fingerprint 4kXxX     
  • The fingerprint expert was asked to testify at the trial.指纹专家应邀出庭作证。
  • The court heard evidence from a fingerprint expert.法院听取了指纹专家的证词。
14 assessment vO7yu     
  • This is a very perceptive assessment of the situation.这是一个对该情况的极富洞察力的评价。
  • What is your assessment of the situation?你对时局的看法如何?
15 biosphere 5Ryyu     
  • The entire biosphere was becoming more transparent.整个生物圈越来越透明。
  • The impact of modern technology on the biosphere is evident worldwide.现代技术对生物圈的影响在全世界是明显的。
16 geologist ygIx7     
  • The geologist found many uncovered fossils in the valley.在那山谷里,地质学家发现了许多裸露的化石。
  • He was a geologist,rated by his cronies as the best in the business.他是一位地质学家,被他的老朋友们看做是这门行当中最好的一位。
17 analytical lLMyS     
  • I have an analytical approach to every survey.对每项调查我都采用分析方法。
  • As a result,analytical data obtained by analysts were often in disagreement.结果各个分析家所得的分析数据常常不一致。
18 previously bkzzzC     
  • 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。
19 pigment gi0yg     
  • The Romans used natural pigments on their fabrics and walls.古罗马人在织物和墙壁上使用天然颜料。
  • Who thought he might know what the skin pigment phenomenon meant.他自认为可能知道皮肤色素出现这种现象到底是怎么回事。
20 overestimated 3ea9652f4f5fa3d13a818524edff9444     
对(数量)估计过高,对…作过高的评价( overestimate的过去式和过去分词 )
  • They overestimated his ability when they promoted him. 他们提拔他的时候高估了他的能力。
  • The Ministry of Finance consistently overestimated its budget deficits. 财政部一贯高估预算赤字。
21 latitudes 90df39afd31b3508eb257043703bc0f3     
  • Latitudes are the lines that go from east to west. 纬线是从东到西的线。
  • It was the brief Indian Summer of the high latitudes. 这是高纬度地方的那种短暂的晚秋。
22 precisely zlWzUb     
  • It's precisely that sort of slick sales-talk that I mistrust.我不相信的正是那种油腔滑调的推销宣传。
  • The man adjusted very precisely.那个人调得很准。
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