美国国家公共电台 NPR As Carbon Dioxide Levels Rise, Major Crops Are Losing Nutrients

 

DAVID GREENE, HOST:

The amount of carbon dioxide in the air is rising because of human activity. And NPR's Merrit Kennedy reports that scientists around the world are trying to understand how more CO2 is going to impact the plants we eat.

MERRIT KENNEDY, BYLINE¹: Plants need carbon dioxide to grow, but its effects on them are complicated. At a government lab outside of Washington, D.C., are rows of controlled chambers³ that look kind of like industrial refrigerators. Scientists are using them to test how plants react to different levels of CO2. Lewis Ziska, who's a plant physiologist⁴ with the U.S. Department of Agriculture, walks me over to a set of these chambers with a crop important to many of us, coffee.

LEWIS ZISKA: This is a sense of the coffee that's growing in there now.

KENNEDY: He swings open the door. It's really bright to mimic⁵ the sun. Green coffee plants stand in neat rows. The CO2 levels in here are lower than they are today. They correspond to levels from about 250 years ago.

ZISKA: CO2 around the pre-industrial age.

KENNEDY: Across the hall, we can see a possible glimpse of the plants' future. Here, there's a chamber² with plants growing at CO2 levels projected for the end of this century.

So we're seeing coffee that look like they're a little bit taller in the high CO2 area versus⁶ the lower CO2 area.

They've all been growing for the same amount of time, but the high CO2 coffee plants are bigger. The extra CO2 seems to be making them grow faster. Scientists have noticed that in many kinds of plants, higher CO2 levels produce bigger crops. That sounds like a good thing, but there's a problem. Take rice, for example. Ziska teamed up with an international group of scientists to study whether high CO2 levels had an effect on the rice's nutritional⁷ value.

ZISKA: Was it changing not just how the plant grew, but the quality of the plant?

KENNEDY: They tested how 18 different kinds of rice responded to CO2 levels that are projected by the end of the century, and the effect was clear. They observed decreases in protein, iron and zinc⁸, and four important B vitamins. Higher CO2 lead to less nutritious⁹ rice. And it's not just rice. The scope of this could be much bigger. Harvard's Sam Myers, who studies the impact of climate change on nutrition, tested CO2's impact on the protein, iron and zinc of a number of crops.

SAM MYERS: Most of the food crops that we consume showed these nutrient¹⁰ reduction.

KENNEDY: The effects varied¹¹. He says wheat, soybeans and field peas showed significant declines in nutritional value. Maize¹² and sorghum¹³ were less affected¹⁴. These studies are enough to raise concerns about how this is going to impact human health, he says.

MYERS: Under what circumstances would this be a big problem?

KENNEDY: Around 600 million people get more than half of their calories from rice. Myers says the people most at risk will be the ones who are highly dependent on a single crop and are struggling to get enough nutrients¹⁵.

MYERS: We're likely to see really significant health impacts from these nutrient changes.

KENNEDY: Going forward, it's going to be important to figure out whether there are other things that can help people who are at risk of nutrient deficiency. Naomi Fukagawa is the director of the USDA's Beltsville Human Nutrition Research Center. If this is indeed found to negatively impact people's health...

NAOMI FUKAGAWA: What we need to then know is, what else do we have as part of their diet that's culturally sensitive that can make up for those differences?

KENNEDY: Scientists are trying to understand why exactly higher CO2 causes plants to lose nutritional value. Finding answers to these questions is going to be crucial as CO2 levels continue to rise. Merrit Kennedy, NPR News, Washington.

1 byline   

n.署名；v.署名

参考例句：

• His byline was absent as well.他的署名也不见了。
• We wish to thank the author of this article which carries no byline.我们要感谢这篇文章的那位没有署名的作者。

2 chamber   

n.房间，寝室；会议厅；议院；会所

参考例句：

• For many,the dentist's surgery remains a torture chamber.对许多人来说，牙医的治疗室一直是间受刑室。
• The chamber was ablaze with light.会议厅里灯火辉煌。

3 chambers   

n.房间( chamber的名词复数 )；（议会的）议院；卧室；会议厅

参考例句：

• The body will be removed into one of the cold storage chambers. 尸体将被移到一个冷冻间里。 来自《简明英汉词典》
• Mr Chambers's readable book concentrates on the middle passage: the time Ransome spent in Russia. Chambers先生的这本值得一看的书重点在中间：Ransome在俄国的那几年。 来自互联网

4 physiologist   

n.生理学家

参考例句：

• Russian physiologist who observed conditioned salivary responses in dogs (1849-1936). （1849-1936）苏联生理学家，在狗身上观察到唾液条件反射，曾获1904年诺贝尔生理学-医学奖。
• The physiologist recently studied indicated that evening exercises beneficially. 生理学家新近研究表明，傍晚锻炼最为有益。

5 mimic   

v.模仿，戏弄；n.模仿他人言行的人

参考例句：

• A parrot can mimic a person's voice.鹦鹉能学人的声音。
• He used to mimic speech peculiarities of another.他过去总是模仿别人讲话的特点。

6 versus   

prep.以…为对手，对；与…相比之下

参考例句：

• The big match tonight is England versus Spain.今晚的大赛是英格兰对西班牙。
• The most exciting game was Harvard versus Yale.最富紧张刺激的球赛是哈佛队对耶鲁队。

7 nutritional   

adj.营养的，滋养的

参考例句：

• A diet lacking in nutritional value will not keep a person healthy.缺乏营养价值的饮食不能维持人的健康。
• The labels on food products give a lot of information about their nutritional content.食品上的标签提供很多关于营养成分的信息。

8 zinc   

n.锌；vt.在...上镀锌

参考例句：

• Brass is formed by the fusion of copper and zinc.黄铜是通过铜和锌的熔合而成的。
• Zinc is used to protect other metals from corrosion.锌被用来保护其他金属不受腐蚀。

9 nutritious   

adj.有营养的，营养价值高的

参考例句：

• Fresh vegetables are very nutritious.新鲜蔬菜富于营养。
• Hummingbirds have discovered that nectar and pollen are very nutritious.蜂鸟发现花蜜和花粉是很有营养的。

10 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。

11 varied   

adj.多样的，多变化的

参考例句：

• The forms of art are many and varied.艺术的形式是多种多样的。
• The hotel has a varied programme of nightly entertainment.宾馆有各种晚间娱乐活动。

12 maize   

n.玉米

参考例句：

• There's a field planted with maize behind the house.房子后面有一块玉米地。
• We can grow sorghum or maize on this plot.这块地可以种高粱或玉米。

13 sorghum   

n.高粱属的植物，高粱糖浆，甜得发腻的东西

参考例句：

• We can grow sorghum or maize on this plot.这块地可以种高粱或玉米。
• They made sorghum into pig feed.他们把高粱做成了猪饲料。

14 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

15 nutrients   

n.（食品或化学品）营养物，营养品( nutrient的名词复数 )

参考例句：

• 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》