TRACING HYDROCARBON CONTAMINATION THROUGH HYPERALKALINE ENVIRONMENTS IN THE CALUMET REGION OF SOUTHEASTERN CHICAGO

The Calumet region of Southeastern Chicago chronicles a history of industrialization with pollution. Slag and other industrial waste products were used to fill the former wetlands in an effort to reclaim them for future development. The waste fill not only creates a heterogeneous and unpredictable geology, but it also produces a hyperalkaline environment where the pH of groundwater has been recorded as high 13.3. Additionally, surface water precipitates calcium carbonate sediment and provides a unique microbial environment. Immediately adjacent to the field site is a former coking facility, where coke, creosote, and coal weather openly on the ground. Weathering hydrocarbons degrade into characteristic polycyclic aromatic hydrocarbons (PAHs) which are unique to the original chemical composition of their parent compound. This research identifies PAHs present in the nearby surface and groundwaters through use of gas chromatography/mass spectrometry (GC/MS) and determines the influence of the alkaline environment on the organic contamination. Through ratio comparison of the PAHs found to known compound profile ratios, the source of organic carbon in the adjacent alkaline sites appears to originate from coke oven emissions. 16s DNA profiling and carbon utilization patterns in Biolog Ecoplates correlated to PAHs found indicate that different hydrocarbon parent products may be influencing the microbial community profiles, even in environments of a similar pH. The use of bioinformatics with PICRUSt to predict metabolic function from the sequenced microbes further examines this relationship. As remediation efforts continue, understanding the geochemistry, weathering and decomposition, microbiology, and distribution of known contaminants is vital for effective local clean-up. PAHs, toxic for humans and the environment, are often targeted for remediation efforts. However, PAHs may often provide carbon-based energy sources for the microbes present within this hyperalkaline ecosystem. Investigating the geochemistry of this site is critical to ongoing research of the unusual microbiology and groundwater patterns in the area as well as providing descriptive data in current and future remediation projects.