To: marcos who wrote (1468 ) 10/3/2001 4:48:57 AM From: Snowshoe Read Replies (1) | Respond to of 8273 OT - Some good news for a change...dailynews.yahoo.com Tuesday October 2 4:57 PM ET Scientists: Great Lakes Are Cleansing Themselves By Lesley Wroughton TORONTO (Reuters) - Canadian and U.S. scientists say they have proof the world's biggest fresh water system, the Great Lakes straddling Canada and the United States, are cleansing themselves of pollutants, and they are planning tests to see if the same is true in the Arctic. The unusual phenomenon was discovered by the bi-national Integrated Atmospheric Deposition Network (IADN), which says tests since 1992 show that significant quantities of polychlorinated biphenyls, or PCBs, and pesticides were being released into the atmosphere by the five Great Lakes -- Erie, Superior, Ontario, Michigan and Huron. The combined surface area of the lakes, which hold about 20 percent of the world's fresh surface water, is about 94,250 square miles. Dr. Keith Puckett, Environment Canada's manager of the IADN, likened the process to giant lungs that have been sucking in polluted air for the past 50 years. Now that the atmospheric levels of many of these pollutants have dropped, the lakes have started breathing out the pollutants again. He said that since Canada and the United States began regulating the use of certain chemicals, levels in the atmosphere started dropping and the lakes then began their own process of cleansing -- at twice the rate they took in. ``As air pollutants over the air drop, this then allows the lakes the opportunity to cleanse themselves and they do this through a process of volatilization or out-gassing of these compounds into the air,'' Puckett told Reuters. Now, Puckett and his team want to do the same tests around an archipelago of islands in the Arctic Ocean. ``Our greatest interest will be a group of small islands where we know that the wildlife there, the seals, walrus, polar bears, have high levels of these pesticides we can try to make same measurements there,'' he said. The studies of the IADN on the Great Lakes show that Lake Ontario, the smallest of the five lakes, released almost two tons of PCBs into the air from 1992 and 1996 as well as significant amounts of dieldrin, a widely banned insecticide. Puckett said data between 1992 and 1996 show there was a decrease of roughly 10 tons of PCBs in the lake and a net decrease of more than 4 tons of dieldrin. From remote IADN stations at each of the lakes, which are linked to a series of satellites, the scientists track some 20 atmospheric pollutants, he said. This year they will expand their monitoring to include mercury. Puckett said it was time to pay closer attention to air pollution from power plant smokestacks, factory boilers, household furnaces, fireplaces and smoking tailpipes on millions of vehicles. Each contributes its share of fine particles and ash, acid gases and smog-forming compounds to the atmosphere, some of which ends up in the Great Lakes. This was part of a new challenge, he said, adding that the IADN was still trying to determine the quantity of pollutants coming from local sources within the Great Lakes Basin, and how much was coming from continental or global sources outside. He estimated that about 30-40 percent of dioxins dropping into the lakes comes from local sources, but toxaphene, a now banned pesticide, was blowing in from the southern United States where it is used on cotton fields. ``There is still material going into the lakes but there is more coming out,'' Puckett said. ``In order to stop the material going in we have to ensure that material still being used in Canada and elsewhere is sort of limited and international agreements are put in place. With that, pollution levels will go down faster.''