2004-8-9
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
fertilizer, 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 genetically engineered plants. He is now
testing a poplar tree that has been genetically engineered to take
in mercury through its roots. The tree then slowly releases the
mercury into the air through its leaves.
Mercury is a highly 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 pregnant 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 reproduce with wild
trees or displace them. Another criticism 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.