2007年VOA标准英语-US Firm to Use Plankton to Combat Greenhouse Ga

By Brian Wagner
Miami
01 June 2007

Scientists are seeking new ways to reverse the build-up of carbon dioxide in the atmosphere, which many believe is the cause of global warming.  VOA's Brian Wagner reports one U.S. project aimed at stimulating¹ plankton² growth in the oceans is raising some debate about its possible effectiveness.

Planktos website screenshot

Environmental groups have long advocated planting trees as one way to reverse the build-up of carbon dioxide in the atmosphere.  Trees absorb small amounts of carbon dioxide to survive. Marine³ scientists say that growing tiny organisms in the ocean known as plankton also can help cut carbon dioxide levels in the atmosphere. 

The U.S. firm Planktos is planning to revive plankton in several regions of the Pacific Ocean as an effective way to absorb atmospheric⁴ CO2 and counter global warming. Planktos climate expert Melodie Grubbs says iron is the key nutrient⁵ needed to stimulate⁶ plankton growth. 

"Once we put that in, iron acts as a catalyst⁷ for photosynthesis⁸, which creates plankton," she said.  "It's a missing nutrient in the ocean, and from that sparks a natural plankton bloom."

Researchers say plankton blooms are down, because less iron dust is being blown onto the ocean's surface by nutrient-rich winds. Planktos says dust supply has fallen 30 percent over the past 30 years, resulting in a 10 percent decline in plankton populations. The Planktos team hopes to reverse the trend by seeding the waters off the Galapagos Islands and several other spots in the Pacific Ocean.

Researchers have been studying the effects of iron seeding on carbon dioxide levels in the atmosphere for more than two decades. Frank Millero, professor of marine chemistry at the University of Miami, helped pioneer some of the techniques in the 1990s. 

"Even at that time people were thinking about this as a solution," he said.  "We were more interested in showing that [lack of] iron was limiting to plant growth."

The Planktos team says it is building on the research of Millero and other scientists. But unlike academics, the California firm hopes to get financing from major companies that release carbon dioxide into the atmosphere. The companies would compensate¹⁰ Planktos for reducing greenhouse gas emissions¹¹ globally, without altering their own manufacturing process.   

Planktos says it hopes to sell these so-called carbon credits or offsets¹².  Profits from the sales will create new opportunities for environmental restoration, says Planktos project manager Michael Bailey.

"We are part of the international carbon credit community, part of that marketing¹³ plan, basically trying to find a way to make money by restoring the oceans and the earth's atmosphere. So this is a beautiful business model," he said.

Experts, however, disagree on how much carbon dioxide is absorbed by plankton blooms, which tend to last no more than two or three weeks. Professor Millero says a key concern is whether plankton seeded with iron can have a long-term effect.

"The problem, if there is one, is if the carbon dioxide in the plant material does not sink to the deep waters and become oxidized there, then the net effect is not as large as you might hope for," he noted¹⁴.

Scientists say plankton has a positive impact on global warming only when carbon-based material in it sinks to deep waters, where it can remain for centuries. Often, some of the material remains¹⁵ near the water's surface, where it is broken down and released back into the atmosphere as carbon dioxide.

Another concern is whether iron seeding can produce more plankton blooms than those that occur naturally. 

David Archer⁹ is a professor of geophysical science at the University of Chicago.

"Fertilizing¹⁶ the ocean, it is not at all clear there is any effect on CO2 in the atmosphere," he said.  "In models of the oceans, if you fertilize¹⁷ the ocean here, and reduce the fertility of the ocean somewhere else, the net effect globally will be very small."

Archer also notes that it is nearly impossible for Planktos to measure how much carbon dioxide is pulled from the atmosphere, if any, and as a result, to calculate the carbon credits that Planktos and other firms want to charge to fund environmental restoration projects. Archer says carbon credits would be better used on more reliable methods of reducing greenhouse gases. 

"You can buy carbon offsets that are used to pay for construction of windmills, or other carbon-free sources of energy to displace coal energy," he added.  "And that has a very clear, easy to demonstrate effect on CO2 in the atmosphere."

Experts may not agree on the best method to fight greenhouse gas emissions, but they do agree that lowering emissions from fossil fuels alone is not enough. Many say the world needs to find techniques to reverse decades of emissions and pull carbon dioxide from the atmosphere.

1 stimulating   

adj.有启发性的，能激发人思考的

参考例句：

• shower gel containing plant extracts that have a stimulating effect on the skin 含有对皮肤有益的植物精华的沐浴凝胶
• This is a drug for stimulating nerves. 这是一种兴奋剂。

2 plankton   

n.浮游生物

参考例句：

• Plankton is at the bottom of the marine food chain.浮游生物处于海洋食物链的最底层。
• The plankton in the sea feeds many kinds of animals. 海的浮游生物成为很多种动物的食物。

3 marine   

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。

4 atmospheric   

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。

5 nutrient   

adj.营养的，滋养的；n.营养物，营养品

参考例句：

• Magnesium is the nutrient element in plant growth.镁是植物生长的营养要素。
• The roots transmit moisture and nutrient to the trunk and branches.根将水分和养料输送到干和枝。

6 stimulate   

vt.刺激，使兴奋；激励，使…振奋

参考例句：

• Your encouragement will stimulate me to further efforts.你的鼓励会激发我进一步努力。
• Success will stimulate the people for fresh efforts.成功能鼓舞人们去作新的努力。

7 catalyst   

n.催化剂，造成变化的人或事

参考例句：

• A catalyst is a substance which speeds up a chemical reaction.催化剂是一种能加速化学反应的物质。
• The workers'demand for better conditions was a catalyst for social change.工人们要求改善工作条件促进了社会变革。

8 photosynthesis   

n.光合作用

参考例句：

• In apple trees photosynthesis occurs almost exclusively in the leaves.苹果树的光合作用几乎只发生在叶内。
• Chloroplasts are the structures in which photosynthesis happens.叶绿体就是光合作用发生的地方。

9 archer   

n.射手，弓箭手

参考例句：

• The archer strung his bow and aimed an arrow at the target.弓箭手拉紧弓弦将箭瞄准靶子。
• The archer's shot was a perfect bull's-eye.射手的那一箭正中靶心。

10 compensate   

vt.补偿，赔偿；酬报 vi.弥补；补偿；抵消

参考例句：

• She used her good looks to compensate her lack of intelligence. 她利用她漂亮的外表来弥补智力的不足。
• Nothing can compensate for the loss of one's health. 一个人失去了键康是不可弥补的。

11 emissions   

排放物( emission的名词复数 )； 散发物（尤指气体）

参考例句：

• Most scientists accept that climate change is linked to carbon emissions. 大多数科学家都相信气候变化与排放的含碳气体有关。
• Dangerous emissions radiate from plutonium. 危险的辐射物从钚放散出来。

12 offsets   

n.开端( offset的名词复数 )；出发v.抵消( offset的第三人称单数 )；补偿；（为了比较的目的而）把…并列（或并置）；为（管道等）装支管

参考例句：

• The following paragraphs deal with intra-source offsets and the so-called \"bubble\" concept. 下面讨论污染源内部的补偿和所谓的“泡泡”概念。 来自英汉非文学 - 环境法 - 环境法
• The preceding paragraphs were concerned with inter-source offsets. 前文牵涉到污染源之间的补偿。 来自英汉非文学 - 环境法 - 环境法

13 marketing   

n.行销，在市场的买卖，买东西

参考例句：

• They are developing marketing network.他们正在发展销售网络。
• He often goes marketing.他经常去市场做生意。

14 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

15 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

16 fertilizing   

v.施肥( fertilize的现在分词 )

参考例句：

• Sometimes the preliminary step must be taken of reducing weed population before fertilizing. 有时候，在施肥之前，必须采取减少杂草密度的预备性步骤。 来自辞典例句
• The self fertilizing garden can also be planted in raised beds. 自我施肥的菜园也可以在苗圃床中种植。 来自互联网

17 fertilize   

v.使受精，施肥于，使肥沃

参考例句：

• Fertilizer is a substance put on land to fertilize it.肥料是施在地里使之肥沃的物质。
• Reading will fertilize his vocabulary.阅读会丰富他的词汇。