Great Lakes ‘exhale’ pesticides
Keith Puckett, manager of the Integrated Atmospheric Deposition Network, a joint Canada-U.S. research team, says the lakes can now get rid of these chemicals because regulatory actions, such as banning certain pesticides, have reduced the amount of the chemicals in the atmosphere.
The levels in the air are low enough now, he says, that the chemicals are evaporating, or “out-gassing,” from the lakes into the atmosphere.
In that time, the Great Lakes released 10 tonnes more PCBs than they took in, and four tonnes more of the pesticide dieldrin. But the release of pollutants from the lakes isn’t dangerous. In fact, says Puckett, this is a sign that the overall amount of these chemicals is decreasing.
When the lakes release the chemicals into the atmosphere, where they end up depends on weather patterns. They could be carried out to the Atlantic Ocean or washed out of the atmosphere in the rain.
Puckett says the amount of pollution coming out of the lakes is small compared to other sources, such as countries that still use chemicals banned in North America.
Puckett says the research has changed the way scientists look at lakes. They can no longer be considered the ultimate destination of chemicals we release into the environment.
The researchers also point out that reducing global levels of pollutants is necessary for cleaning up the Great Lakes. Much of the chemical pollution entering the lakes comes from other countries around the world, they say.