Annual Report 2010

Civil and Environmental Engineering

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Keeping toxins out of our waterways

Polychlorinated biphenyls (PCBs) are potentially toxic compounds with no known smell or taste that are of tremendous interest to engineers and human toxicologists.

PCBs found their way into lakes and streams long ago, entering the food supply through animal products. This compound has remained in the food supply thanks to landfill leaks and other sources and are found in farm-raised salmon and types of freshwater fish.

PCBs are keeping University of Iowa professors and graduate students busy, as their discoveries are being regularly chronicled by the media.

A UI news release distributed last January announced that researchers found sediments of the Indiana Harbor and Ship Canal (IHSC) in East Chicago, IN, to be contaminated with PCBs.

The IHSC, part of the Calumet River tributary of Lake Michigan, will begin being dredged in the next few years to maintain the proper depth for ship traffic, with uncertain environmental impacts in regard to PCBs. Scientists aren't sure whether dredging will help the situation by removing the potentially harmful compounds or hurt it by stirring them up.

The origin of the PCBs is unknown, but they strongly resemble Aroclor 1248, a potentially toxic compound that may pose direct health hazards to humans. This mixture was used in hydraulic fluids, vacuum pumps, plasticizers and adhesives, according to the U.S. Department of Health and Human Services.

"The presence of PCBs is important because dredging will impact the fate and transport of chemicals," said Keri Hornbuckle, professor of civil and environmental engineering in the UI College of Engineering and corresponding author of the study, published in the journal Environment International.

"It is quite possible that dredging will provide a major improvement in the situation. It may remove PCBs that are available to fish and other wildlife, and reduce the release of PCBs from the sediments," she said. "On the other hand, dredging might increase the availability and mobility of PCBs. Now that we know PCBs are present, these questions are pertinent."

Hornbuckle collaborated on the research with first author Andres Martinez, a graduate student in civil and environmental engineering; Karin Norstrom, a postdoctoral student in civil and environmental engineering; and Kai Wang, an assistant professor of biostatistics in the college of public health.

PCBs present in major urban areas

Another news release in January stated that UI scientists identified multiple sources of PCBs in Cleveland and Chicago.

The study suggests that scientists should investigate multiple sources of PCBs in urban areas instead of focusing on one large source.

Scientists have known that PCBs exist in urban atmospheres, but they didn't know if the sources were localized or distributed across the cities. Using air samplers in Cleveland and Chicago, UI researchers discovered multiple sources.

"Acknowledging and examining the multiple sources of PCBs will be helpful in developing remediation efforts," Hornbuckle said. "Our work indicates that we probably cannot focus on just one large source in a city."

The study was published by the journal Environmental Science and Technology. Authors of the paper are Hornbuckle; Carolyn Persoon, a graduate student in civil and environmental engineering; Thomas Peters, an assistant professor of occupational and environmental health in the College of Public Health; and Naresh Kumar, an assistant professor of geography in the UI College of Liberal Arts and Sciences.

Funding for the research projects were provided by the National Institute for Environmental Health Sciences (NIEHS/NIH) Iowa Superfund Basic Research Program