The PCB profiles in sediment, water and air support their determination that the contaminated sediment is a major source of PCBs into the water and air above it, noted Hornbuckle and colleagues Andres Martinez, lead author and civil and environmental engineering graduate student, and Kai Wang, associate professor of biostatistics in the UI College of Public Health.
"We were not surprised to discover that PCBs were continuously emitted from the sediments of the Indiana Harbor and Ship Canal. However, without our study, there was no way to determine how much was being released. Now we better understand the magnitude of the PCB release to Lake Michigan and to the air over the harbor and canal," Hornbuckle said. "We have found that this tributary releases more PCBs to Lake Michigan than any other known direct discharge of PCBs to the lake."
"We don't know if the airborne PCBs are dispersed into the surrounding community, Hornbuckle added. "Furthermore, we don't yet know if the emissions of airborne PCBs from this contaminated water system are a large source compared to many other possible sources in the area.
"One of the surprising findings of our study is that there appear to be upstream sources. Although we examined PCBs within the navigational regions of the canal, we were not able to study regions of the canal that are inaccessible to our research vessel. But our study suggests that there are large sources of PCBs in the upper reaches of the canal," she said.
Manufactured from about 1930 until being banned in the 1970s due to their toxicity and persistence in the environment, PCBs were widely used as coolants, in electrical transformers and in a wide variety of products ranging from waterproofing compounds to paints and pesticides.
|Contact: Gary Galluzzo|
University of Iowa