A University of Iowa study supports an earlier UI report that found polychlorinated biphenyls (PCBs) in sediments lining the Indiana Harbor and Ship Canal (IHSC) in East Chicago, Ind. The study also presents data showing that the sediments are a significant source of PCBs found in surrounding air and in Lake Michigan.
The study appears in the online edition of the journal Environmental Science and Technology (ES&T), a publication of the American Chemical Society and is scheduled for formal journal publication in April.
The study emphasizes the fact that it is unknown whether the proposed dredging of the canal to improve its navigability will result in the release of greater amounts of PCBs due to disturbing the sediments or lesser amounts through sediment removal. However, one thing is certain -- PCBs are already leaching into the environment in significant amounts, said Keri Hornbuckle, professor in the UI College of Engineering Department of Civil and Environmental Engineering and corresponding author on the study.
"We have analyzed PCBs in surficial sediment, water, suspended particles and air and examined the potential for chemical movement in the harbor system," Hornbuckle said. "We have shown that the system is currently a significant source of PCBs to the air and to Lake Michigan, even under quiescent conditions."
In order to obtain accurate estimates of each PCB emission, the researchers used on-site sampling in conjunction with a predictive model for chemical mass transfer and a mathematical approach to estimate the variability in the results.
They found that annually about 4 kilograms (kg) were released from the sediment to the water and about 7 kg were transferred from the water to the air. The PCB input from the upstream regions of the canal system measured 45 kg per year and the amount exported to Lake Michigan was 43.9 kg. The study noted that the measured PCBs account for nearly all the PCB in
|Contact: Gary Galluzzo|
University of Iowa