Multimedia Source Apportionment of Semivolatile Organic Contaminants in the Chicago Area of Influence.

The Chicago region suffers from a legacy of historic contamination and continuous release of industrial and traffic related pollution. Persistent Organic Pollutants (POPs) like Polycyclic Aromatic Hydrocarbons (PAHs) and Polychlorinated Biphenyls (PCBs) affect human health as well as Lake Michigan, the Chicago Area Waterway and downstream aquatic system, high quality native remnant habitats, and hundreds of threatened and endangered species. The primary objective of this research is to investigate the utility of receptor-based source apportionment approaches to identifying the sources of PAHs and PCBs to multiple environmental media in the Chicago metropolitan ‘area of influence’. The multimedia focus of this investigation includes an industrial harbor air-shed (the Indiana Harbor and Canal; IHC) and a less urbanized aquatic system (the Illinois River). Positive Matrix Factorization (PMF) is utilized alongside other source apportionment techniques (UNMIX, PAH diagnostic ratios) as a powerful and incisive tool for quantitative source determination of contaminants. Source apportionment results demonstrate the IHC air-shed has been dominated over the last decade by PAHs from nearby byproduct recovery coke production, followed by petroleum storage activities and vehicular emissions, emphasizing the need for industrial control of PAH emissions. The weight of evidence approach taken to confirm results included extensive use of reference profiles, meteorological data, temperature correction, spatial and temporal analysis, and reported and historical emissions information. Illinois River sediment PAH source profiles resembled background soils, coal-derived sources like coal tar sealcoat, and a traffic-based source that suggest mixed upland sources rather than direct inputs to the system. IHC atmospheric PCBs were driven by legacy contamination in the environment, generally resembling the Aroclor mixtures that were used in industry. Canal sediments contaminated with Aroclor 1248 are a main contributor to local PCB levels. These findings can inform policy and project decisions for environmental work at these locations, and establish a baseline for future analyses to monitor their efficacy. Pollution prevention, control, and removal solutions are suggested to reduce impacts to the surrounding communities and natural areas. Limitations of the models, data, contaminants, media, and applications are also examined and recommendations made to support successful source apportionment.