From Geotimes:
What keeps passengers safe when they fly in the winter may not be as safe for ecosystems. Researchers examining the environmental harm done by airplane de-icing and anti-icing fluid runoff have found that such runoff from airports located near bodies of water — including 45 of the 50 busiest airports in the United States — could spell trouble for aquatic ecosystems.
Although de-icer fluid is known to be toxic, de-icers have generally become less harmful since the mid-1990s, says Steven Corsi of the U.S. Geological Survey (USGS). But anti-icers — de-icers with additives that help the fluid stick to the surface and prevent the formation of new ice — have stayed just as toxic, he says. Airports use de-icers to remove ice from planes before takeoff, spewing between 100 and several thousand gallons per aircraft with each application, depending on conditions. Some of the fluid sticks to the plane, but 75 to 80 percent escapes into the surrounding environment, according to a 1995 Federal Aviation Administration report.
More here.