The Great Lakes Exhale and We Can All Breathe Easier

According to a report from the Integrated Atmospheric Deposition Network, the EPA and Environment Canada that measures the effect of chemicals on the Great Lakes Basin, the\r\nlakes are cleansing themselves of pollutants.

The Great Lakes might be greater than we thought. Scientists from the United States and Canada say there is good news lurking in the cold depths of the Great Lakes. According to a report out of the Integrated Atmospheric Deposition Network (IADN), a joint effort by the U.S. Environmental Protection Agency (EPA) and Environment Canada to measure the effect of chemicals on the Great Lakes Basin, the lakes are ridding themselves of pollutants. And they''re doing it much like we would breathe out bad air and take in good air, says one scientist.

According to IADN, tests for nearly a decade show that significant quantities of PCBs and pesticides have been released into the atmosphere by the Great Lakes, a process which Dr. Keith Puckett, Environment Canada''s manager of the IADN, compared to breathing. He said the Great Lakes are acting like giant lungs that have been sucking in polluted air for the past 50 years and have started to breathe out.

As the amount of air pollutants in the air over the Great Lakes decrease, it "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," said Puckett.

The five Great Lakes - Superior, Michigan, Erie, Huron and Ontario - straddle the border of Canada and the United States and hold about 20 percent of the world''s fresh water.

IADN was created to help establish the significance of long-range atmospheric transport of toxic substances. It was designed to assess the magnitude and trends of atmospheric deposition of certain chemicals, including polychlorinated biphenyls (PCBs), chlorinated pesticides, and trace metals such as lead and mercury. Stations on remote shores of each of the Great Lakes collect regional contaminant data that is representative of the air over each lake and that is not affected by local sources. Concentrations of target chemicals are measured in rain and snow, airborne particles, and airborne organic vapors.

According to Puckett and the scientists at IADN, as the United States and Canada reduced or eliminated the use of certain chemicals and the atmospheric levels of those chemicals began to drop, the Great Lakes began to "exhale" the pollutants. In other words, they began the process of cleaning themselves.

Lake Ontario, the smallest of the five lakes, released almost two tons of PCBs into the air from 1992 and 1996, and showed a total decrease of nearly 10 tons of PCBs.

The IADN has several projects in the works. The group would like to run the same tests it ran in the Great Lakes around an archipelago of islands in the Arctic Ocean. The IADN is also trying to determine how much of the pollutants found in the Great Lakes Basin is coming from sources within the basin and how much is from outside sources.

In related news, the "State of the Great Lakes 2001" report was released Sept. 27 by the governments of Canada and the United States. The report assesses the water quality of the Great Lakes Basin using 33 indicators such as drinking water quality, chemical contaminants in edible fish tissue, toxic chemical concentrations in offshore waters and amphibian diversity and abundance. The report gave a mixed review to the status of the chemical, physical and biological integrity of the waters of the Great Lakes Basin.

Among other things, the report noted that:

  • Surface waters are still among the best sources of drinking water in the world.
  • Progress has been made both in cleaning up contaminants and in rehabilitating some fish and wildlife species.
  • Invasive species continue as a significant threat to Great Lakes biological communities.
  • Atmospheric deposition of contaminants from distant sources outside the basin confound efforts to eliminate these substances.
  • Urban sprawl threatens high quality natural areas, rare species, farmland and open space.
  • Development, drainage and pollution are shrinking coastal wetlands.

By Sandy Smith

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