Great Lakes cleanse themselves
ABC Online 8/10/2001
Scientists in North America say the Great Lakes on the US-Canadian border are cleansing
themselves of the pollution that they have absorbed in the last half of the 20th century.
The BBC reports, the lakes between them hold about one-fifth of the world's fresh surface
water.
Environmental researchers in Canada and the USA say the five great lakes are acting like
giant lungs.
As the use of agricultural and industrial chemicals increased in the second half of the
20th century, the Lakes in effect breathed in pollutants, absorbing them from high
concentrations in the air.
A group of chemicals, PCBs, which have been linked to cancer, became concentrated in the
food chain in the water, and especially in fish.
However, once regulations imposed to curb the use of chemicals began to take effect, and
atmospheric concentrations of PCBs started to decrease, the levels of pollutants in the
Lakes also began to drop. END OF REPORT
Back |
|
