官方APP下载:英语学习播客(支持苹果手机、安卓手机)
创办于2003年
UNSV记不住?那就记中文谐音“忧安思危”吧!
  Slow and Steady Wins the Race!
UNSV英语学习频道 - Slow and steady wins the race!
公众微信服务号(英语全能特训)
英语全能特训(微信公众服务号)
UNSV英语学习频道淘宝网店
客服短信:18913948480
客服邮箱:web@unsv.com
初级VIP会员
全站英语学习资料下载。
¥98元/12个月

ENVIRONMENT REPORT - Great Lakes Clean Themselves

作者:George Grow 发布日期:10-19-2001

This is the VOA Special English ENVIRONMENT REPORT.

Scientists say they have evidence that the world's biggest freshwater lake system is cleaning itself of pollutants. North America's Great Lakes hold about twenty percent of the world's fresh surface water. Pollution has been a problem there for years. Yet scientists now say large amounts of chemical pollutants are disappearing from the water's surface. A team of Canadian and American scientists reported the unusual finding.

The five Great Lakes are named Superior, Michigan, Huron, Erie and Ontario. They extend from the middle western state of Minnesota to the eastern state of New York. Only Lake Michigan lies completely within the United States. The United States and Canada share the other four lakes. They also form part of the border between the two countries. A treaty signed in Nineteen-Oh-Nine provides for control of the lakes by the two countries.

The Great Lakes form the most important inland waterway in North America. The five lakes and their waterways are important to the economies of the United States and Canada.

In the new study, the scientists measured levels of several harmful chemicals that have washed into the lakes. They include chemicals to kill insects and polychlorinated biphenyls, or P-C-Bs. P-C-Bs are chemicals used in industry. The United States and Canada have banned P-C-Bs because of their links to cancer. Yet they still are used in some developing countries.

The study found that Lake Ontario alone released almost two metric tons of P-C-Bs between Nineteen-Ninety-Two and Nineteen-Ninety-Six. The five lakes decreased their combined levels of P-C-Bs by about ten metric tons during the period. Levels of one banned chemical dropped more than four metric tons.

The scientists believe the chemicals were released into the atmosphere. Keith Puckett of Canada's environment agency worked on the project. He said the lakes are like huge lungs that have been breathing in pollutants for the past fifty years. Mister Puckett says now it is as if the lakes are starting to breathe out again.

Mister Puckett adds that air pollution near the Great Lakes remains a threat. He called for increased efforts to control pollution from power production centers, factories, vehicles and other causes.

This VOA Special English ENVIRONMENT REPORT was written by George Grow.

版权所有©2003-2019 南京通享科技有限公司,保留所有权利。未经书面许可,严禁转载本站内容,违者追究法律责任。 互联网经营ICP证:苏B2-20120186
网站备案:苏公网安备 32010202011039号苏ICP备05000269号-1中国工业和信息化部网站备案查询
广播台