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Examining pollution in Great Lakes sediment

Videography by Rachel Glass

An Li and Karl Rockne have been working together for more than five years to monitor and measure environmental pollutants in Great Lakes sediment.

Through the Great Lakes Sediment Surveillance Program, Li, professor of environmental and occupational health sciences in the UIC School of Public Health, and Rockne, professor and interim head of civil and materials engineering in the UIC College of Engineering, have collected more than 1,000 sediment samples in the lakes.

Rockne analyzes the physical structure of the sediment samples, looking for information that will provide clues of how the sediment deposited and what that means for the timing or speed with which chemical pollutants have accumulated in the lake bottom mud.

Li looks at the chemical composition of the samples to identify what kinds of industrial pollutants are present. These typically fall into one of two categories: legacy chemicals, or those that may persist in the environment even though their production has ceased (the pesticide DDT, for example) and chemicals of emerging concern. These chemicals can be known or unknown.

One reason the surveillance program is so important, Li said, is that “we need to constantly be on the lookout for the presence of new chemicals in the environment that may be hazardous to health.” Li recently discovered a suite of chemicals called polyhalogenated carbazoles in the deep sediments of Lake Michigan. These are similar in structure to dioxins and PCBs, but more research needs to be done to determine where they came from and if they are toxic.

“We keep finding new things — that’s the fun part,” Li said.