This study hypothesized that Chicago remains an ongoing source of legacy and emerging contaminants to Lake Michigan. To address this, we measured PCBs, PAHs, pesticides, emerging flame retardants (FR), and PBDEs in air and water samples collected simultaneously, approximately 5km from the Chicago shoreline. We predicted air-water exchange though application of physical-chemical properties of each compound, local meteorological data, and the compound specific air and water concentrations. Air-water exchange was modeled, utilizing MATLAB® R2015a, with combination of the following: Whitman’s two-film resistance model, Deacon’s boundary model, three-phase partitioning model, and two parameter Weibull distribution. Gas-phase concentrations ranged from 0.19 to 1.1 ng m-3, &lt;LOQ to 90 pg m-3, 56 to 440 pg m-3, 30 to 250 pg m-3, &lt;LOQ to 40 pg m-3 for ΣPCB, ΣPAH, pesticides, ΣPBDE, and ΣFR, respectively. Dissolved-phase concentrations ranged from 150 to 170 pg L-1, 4.45 to 7.58 ng L-1, 0.05 to 5.3 ng L-1, 17.3 to 163 pg L-1, 1.4 to 7.4 pg L-1 for ΣPCB, ΣPAH, pesticides, ΣPBDE, and ΣFR, respectively. As expected for the Aroclor history of the area, the distribution of congeners in air and water resembled of Aroclor 1242, 1248, and 1254. For the entire period of study, the congener specific (PCB) net flux ranged from -27 to 18 ng m-2 day-1, PCB107+124 and PCB11, respectively; net ΣPCB fluxes were determined to range from -320 to 84 ng m-2 day-1 with an average of -160 ± 170 ng m-2 day-1, where positive and negative fluxes indicate volatilization and absorption, respectively. SW/W winds, originating from Chicago, exhibited increased absorption of medium to higher chlorinated congeners and net absorption of SPCB; whereas N/NE/E winds, originating from across the lake, exhibited net volatilization. Despite the limited study period, this study displays strong evidence that Chicago remains a source of PCBs, primarily medium to higher chlorinated congeners (tetra-, penta- and so on), to Lake Michigan. Furthermore, southern Lake Michigan was found to be a volatilization source of a non-Aroclor congener, PCB11; average net flux of 14 ng m-2 day-1, regardless of wind direction.

Air-Water exchange of legacy and emerging contaminants in Lake Michigan near Chicago

253rd National Meeting (2017)

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