Great Lakes Project Awarded $5 Million
A project to measure levels of airborne toxic chemicals being deposited in the Great Lakes was recently awarded a $5 million grant from the U.S. Environmental Protection Agency. The Integrated Atmospheric Deposition Network (IADN), led by SPEA professor Ronald Hites and research scientist Ilora Basu, began in 1990 under an agreement between the U.S. EPA and Environment Canada. IU has been in charge of the U.S. portion of the study since 1994, and the grant will extend IU's oversight of the project for a further five years.
The IADN project involves collecting air samples at regular intervals at master stations on each of the five Great Lakes and at several satellite stations. The U.S., through Indiana University, is responsible for master stations on Lakes Michigan, Superior and Erie and satellite stations in Chicago and Cleveland. Canada focuses on Lakes Huron and Ontario.
"Atmospheric deposition is one of the main ways that toxic chemicals get into the Great Lakes," said Gary Gulezian, director of the EPA's Great Lakes National Program Office. "IADN is a critical long-term Great Lakes monitoring program that not only estimates the loadings of these chemicals to the Great Lakes, but also tracks environmental progress and identifies potential source regions."
Hites said the grant will enable IU to provide important trend data on chemicals -- including polychlorinated biphenyls (PCBs), chlorinated pesticides such as DDT, polycyclic aromatic hydrocarbons and brominated fire retardants -- reaching the Great Lakes through the atmosphere.
"We also want to nail down something that we've seen in the last couple of years -- namely, the huge impact that cities have," Hites said. "Cities are clearly where the sources of the chemicals are, and they're leaking out into the lakes."
The Great Lakes are the largest surface freshwater system on the Earth, containing about 84 percent of North America's surface fresh water and about 21 percent of the world's supply. Roughly 10 percent of the U.S. population and more than 30 percent of Canada's population live in the Great Lakes basin.
For IADN, air samples are taken every 12 days, providing a mass of data that allow scientists to study trends in the deposition of chemicals to the Great Lakes and that help policy makers better understand how to manage the effects of pollution. "Just a few measurements over a few months don't tell you much," Hites said. "You've got to do these measurements continuously over a long time period."
While concentrations of some of these chemicals in the air are low, many do not easily break down. They are persistent, and they bioaccumulate in the tissues of animals. For many people, consumption of fish and wildlife is the primary pathway for exposure to the chemicals. As a result, government agencies continue to issue advisories against eating Great Lakes fish.
PCBs have been shown to cause cancer in animals and have been linked to other serious health problems, including effects on the immune, reproductive, nervous and endocrine systems.
Hites said monitoring to date has yielded some surprises. One is that concentrations are dramatically higher in cities, not only for industrial chemicals such as PCBs, but also for some pesticides. While DDT was widely used in agriculture before being banned from most uses in the U.S. in the 1970s, it was also sprayed to control mosquitoes in cities. Another pesticide, chlordane, was used to treat homes for termites. Apparently, these chemicals stay in the urban environment for decades, before getting into the air and being transported to the lakes.
Another surprise, Hites said, is that while concentrations of some of these chemicals are going down, the decline isn't as fast or steady as might have been expected. For example, the manufacture and use of PCBs was banned in the U.S. in 1976, but they have remained in use in products that were produced before that time. Great Lakes PCB levels went down for a time, and then actually have increased before resuming a gradual decline.
"The regulations picked the low-hanging fruit -- they found a few major sources and shut those down," Hites said. "But over the past 19 years, during the time of this study, PCB concentrations have not gone down very much at all."