UI study measures levels of PCBs flowing from Indiana canal to air and water

February 24, 2010

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 inputs and losses to the navigational regions.

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.
-end-
The paper is part of a special topic focus issue of ES&T for which Hornbuckle and Larry Robertson, professor in the UI College of Public Health, are special editors.

The study was funded by the Iowa Superfund Basic Research Program and the National Institute of Environmental Health Sciences.

The study can be found online at: http://pubs.acs.org/doi/abs/10.1021/es902911a?prevSearch=%255Bauthor%253A%2Bhornbuckle%255D&searchHistoryKey.

STORY SOURCE: University of Iowa News Services, 300 Plaza Centre One, Iowa City, Iowa 52242-2500

MEDIA CONTACTS: Keri Hornbuckle, UI College of Engineering, 319-384-0789, keri-hornbuckle@uiowa.edu; Gary Galluzzo, University News Services, 319-384-0009, gary-galluzzo@uiowa.edu

University of Iowa

Related Sediment Articles from Brightsurf:

The first detection of marine fish DNA in sediment sequences going back 300 years
Far too little is known about the long-term dynamics of the abundance of most macro-organism species.

Microbial diversity below seafloor is as rich as on Earth's surface
For the first time, researchers have mapped the biological diversity of marine sediment, one of Earth's largest global biomes.

Climate change could deliver more sediment and pollution to the San Francisco Bay-Delta
Climate change could deliver more silt, sand and pollution to the San Francisco Bay-Delta, along with a mix of other potential consequences and benefits, according to a new study in the AGU journal Water Resources Research.

Urine sediment test results, diagnoses vary significantly across nephrologists
A new study shows that nephrologists do not always agree on their interpretation of images from urine sediment tests, which are frequently ordered to evaluate a variety of kidney diseases.

Texas cave sediment upends meteorite explanation for global cooling
Texas researchers from the University of Houston, Baylor University and Texas A&M University have discovered evidence for why the earth cooled dramatically 13,000 years ago, dropping temperatures by about 3 degrees Centigrade.

Model links patterns in sediment to rain, uplift and sea level change
In a recent study, researchers from The University of Texas at Austin show that a natural record - sediments packed together at basin margins - offers scientists a powerful tool for understanding the forces that shaped our planet over millions of years, with implications on present day understanding.

Massive seagrass die-off leads to widespread erosion in a California estuary
The large-scale loss of eelgrass in a major California estuary -- Morro Bay -- may be causing widespread erosion.

Revealed from ancient sediment: Mangrove tolerance to rising sea levels
The growth and decline of mangrove forests during the final stages of Holocene deglaciation offers a glimpse into how the ecosystems will respond to the rapidly rising seas projected for the future, according to a new study.

New sediment record reveals instability of North Atlantic deep ocean circulation
In the future's warmer climate, large, abrupt and frequent changes in ocean ventilation may be more likely than currently assumed, according to a new study.

Study examines the impact of oil contaminated water on tubeworms and brittlestars
A new study published by Dauphin Island Sea Lab researchers adds a new layer to understanding how an oil spill could impact marine life.

Read More: Sediment News and Sediment Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.