The Indiana Harbor and Ship Canal is located in East Chicago, Ind., on the southwest shore of Lake Michigan. The U.S. Army Corps of Engineers has proposed dredging sediments from the canal to allow its continued use as a navigable waterway. Researchers have discovered that some sediments are contaminated with high levels of polychlorinated biphenyls (PCBs). (Courtesy: Wikimedia)

U. IOWA—The Indiana Harbor and Ship Canal is contaminated with polychlorinated biphenyls (PCBs) and scientists are unsure whether planned dredging in the next few years will help or hurt the situation.

“The presence of PCBs is important because dredging will impact the fate and transport of chemicals,” explains Keri Hornbuckle, professor of civil and environmental engineering at the University of Iowa and corresponding author of the study.

Employing tandem mass spectrometry, an analytical technique to determine the elemental composition of a sample or molecule, the researchers found high levels of PCBs.

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.

“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,” Hornbuckle says.

“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. The study was published in the journal Environment International.

Prior to this study, there was little published data of the spatial extent and concentration magnitude of PCBs in the sediment in the canal, Hornbuckle says.

The Army Corps of Engineers reported that PCBs have existed in canal sediment since 1977, but has not published a full report.

Funding was provided by the National Institute for Environmental Health Sciences Iowa Superfund Basic Research Program.

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