Concentrations and gas/particle partitioning of PCBs in Chicago Yu¨cel Tasdemir a, * , Nedim Vardar b , Mustafa Odabasi c , Thomas M. Holsen d a Uludag University, Faculty of Engineering and Architecture, Department of Environmental Engineering, 16059 Gorukle/Bursa, Turkey b Interamerican University, School of Engineering, 500 Dr. John Will Harris, 00957 Bayamon, P.R., USA c Dokuz Eylul University, Faculty of Engineering, Department of Environmental Engineering, Kaynaklar Campus, 35160 Buca/Izmir, Turkey d Clarkson University, Civil and Environmental Engineering Department, Box 5710, Postdam, NY 13699, USA Received 1 October 2003; accepted 9 February 2004 ‘‘Capsule’’: Results suggest that the area southwest of Chicago can be an important local or regional source sector for PCBs. Abstract Thirty seven air samples were collected in Chicago, IL from June to October 1995 and analyzed for gas and particle concentrations of polychlorinated biphenyls (PCBs). Lower molecular weight (MW) PCBs dominated the samples and on average 95% of the S 50 PCB concentration (gas C particulate) was in the vapor phase. S 50 PCB concentrations were classified based on prevailing winds (lake and land). The S 50 PCB concentration varied between 0.42 and 5.21 ng/m 3 (1:80 G 1:70 ng=m 3 ) for lake and 0.53 and 8.31 ng/m 3 (2:41 G 2:15 ng=m 3 ) for land wind directions. Back trajectory analyses suggested that SW of Chicago can be an important local or regional source sector for PCBs. Partitioning between gas and particulate phases was modeled using the Junge- Pankow model. The measured particle phase concentrations for low MW PCBs were lower than those predicted by the model while the opposite was observed for high MW PCBs. Plots of gas/particle partition coefficient (log K p ) vs. subcooled liquid vapor pressure (log p L 0 ) had reasonable correlations for individual samples but the slope varied among the samples. Samples that originated from over the lake had higher slopes than samples that originated from over the land. Ó 2004 Elsevier Ltd. All rights reserved. Keywords: PCBs; Gas-particle partitioning; Back trajectory; TSP 1. Introduction Polychlorinated biphenyls (PCBs) are semi volatile organic compounds (SOCs) found in air, soil, water and organisms (Achman et al., 1993; Franz and Eisenreich, 1993; Asplund et al., 1994; Jackson and Carpenter, 1995; Dahle et al., 1995; Garcia-Alonso et al., 2002). PCBs may enter the atmosphere from transformers, incinerators, landfills, sludge drying beds, or soil and air/water exchange (Murphy et al., 1985; Hornbuckle et al., 1993; Hsu et al., 2003). PCBs in the atmosphere are mainly in the vapor phase (Murphy and Rzeszutko, 1977; Hermanson and Hites, 1989; Tasdemir, 1997; Mandalakis et al., 2002) and they partition between the gas and particulate phase based on their concentrations, vapor pressures, the ambient air temperature, and the concentration of particulate matter present in the air (Cotham and Bidleman, 1992; Falconer et al., 1995; Hoff et al., 1996). Fate, transport, atmospheric residence time, and removal processes (dry or wet deposition) of SOCs are mainly affected by their gas and particle phase partitioning (Junge 1977; Pankow 1987; Bidleman 1988; Hoff et al., 1996; Tasdemir, 1997; Yeo et al., 2003). The Junge-Pankow model was developed to predict the reversible adsorption of gases to particles (Pankow et al., 1993; Pankow, 1994). The basis of the model is a linear Langmuir isotherm with compound adsorption expressed by the relationship between aerosol surface * Corresponding author. E-mail address: tasdemir@uludag.edu.tr (Y. Tasdemir). Environmental Pollution 131 (2004) 35e44 www.elsevier.com/locate/envpol 0269-7491/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.envpol.2004.02.031