AGRICULTURE REPORT - Poplar Trees as Pollution Fighters

AGRICULTURE REPORT - Poplar Trees as Pollution Fighters
By Mario Ritter

Broadcast: Tuesday, August 10, 2004

This is Steve Ember with the VOA Special English Agriculture Report.

Poplar trees can be cut down and used for wood or paper. Or they can be left to stand and also used for different purposes. Poplar trees are often used to guard against water pollution. They are planted as barriers to keep waste from entering groundwater and rivers.

Their large root systems trap waste, like nitrogen-based fertilizer¹, and help reduce the loss of soil. Now, poplar trees may become important tools for cleaning the environment. Some scientists think poplars can be a valuable resource to remove poisonous substances from the soil.

The poplar tree is found in many places in the northern half of the world. It is a fast growing tree that requires a lot of water. Different kinds of poplar trees are native to Asia, Europe and North America. In the United States, poplars are also known as cottonwood trees.

For years, Professor Richard Meagher of the University of Georgia has done research on genetically² engineered plants. He is now testing a poplar tree that has been genetically engineered to take in mercury³ through its roots. The tree then slowly releases⁴ the mercury into the air through its leaves.

Mercury is a highly⁵ poisonous metal. It is a waste product of many industries. Mercury builds up in fish and other living things. It is especially dangerous to the development of children. This is why women who might get pregnant⁶ are warned to be careful about mercury levels in the food they eat.

Professor Meagher is testing his genetically engineered poplars on some land in Danforth, Connecticut. The ground is polluted with mercury from a factory once there. The scientist has planted one hundred sixty poplars to remove the pollution.

Not everyone likes the idea to use genetically engineered trees to collect mercury. Critics say these could reproduce⁷ with wild trees or displace⁸ them. Another criticism⁹ is that the poplars only spread mercury rather than remove it from the environment. The professor says it is better to spread the mercury than have it all in one place where it could be more of a health risk.

Still, there is great interest in using plants to process and control harmful substances. And poplar trees are among the most studied.

But using poplars as a natural barrier against water pollution is not a new idea. The Chinese have used them this way for thousands of years.

This VOA Special English Agriculture Report was written by Mario Ritter. This is Steve Ember.

1 fertilizer   

n.肥料，化肥

参考例句：

• Fertilizer enriches the soil.肥料使土壤肥沃。
• Get some more fertilizer for the garden.给花园再多施些肥料。

2 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物

3 mercury   

n.汞，水银，水银柱

参考例句：

• The liquid we can see in thermometers is mercury.我们看到的温度计里的液体是水银。
• Mercury has a much greater density than water.水银的密度比水大得多。

4 releases   

v.释放( release的第三人称单数 )；放开；发布；发行

参考例句：

• Nuclear fission releases tremendous amounts of energy. 核裂变释放出巨大的能量。 来自《现代汉英综合大词典》
• Zemel says that when calcium levels are low, the body releases a hormone that helps squeeze the most out of every available milligram of the mineral. 泽莫尔博士说，当人体中的钙含量偏低时，身体里就会产生一种荷尔蒙，它能帮助肌体最大限度地吸收所摄入的钙。 来自《简明英汉词典》

5 highly   

adv.高度地，极，非常；非常赞许地

参考例句：

• It is highly important to provide for the future.预先做好准备非常重要。
• The teacher speaks very highly of the boy's behaviour.老师称赞这个男孩的表现。

6 pregnant   

adj.怀孕的，怀胎的

参考例句：

• She is a pregnant woman.她是一名孕妇。
• She is pregnant with her first child.她怀了第一胎。

7 reproduce   

v.生育，繁殖，复制，重做

参考例句：

• The machine can reproduce a key in two minutes.这机器能在两分钟内复制一把钥匙。
• The picture will reproduce well.这照片会印得很清楚。

8 displace   

vt.取代，迫使...离开家园，使离开原位

参考例句：

• The extraordinary thing was that french did not displace English.奇特的是，法语没有取代英语。
• At present,obviously,nevertheless,he was not likely to displace himself.但时至今日，很清楚，他不可能再迁徙了。

9 criticism   

n.批评，批判，指责；评论，评论文章

参考例句：

• Some youth today do not allow any criticism at all.现在有些年轻人根本指责不得。
• It is wrong to turn a deaf ear to other's criticism.对别人的批评充耳不闻是错误的。