Occurrence and Distribution of Two Hydroxylated Polychlorinated Biphenyl Congeners in Chicago Air

We measured hydroxylated polychlorinated biphenyls (OH-PCBs) in both gas and particulate phases in 30 Chicago air samples, the first report of OH-PCBs in environmental air samples. Concentrations of 2OH-PCB2 and 6OH-PCB2 in both phases were similar to those of PCB2 measured in the same samples, from nondetect to 11 pg m(-3) and 12 ng g(-1) for the gas and particulate phases, respectively. We found that OH-PCB2 congeners sorbed more to particulates than did PCB2, seasonal variability was larger than spatial variability across Chicago, and partial pressure and temperature strongly correlated with the two OH-PCBs (p < 0.0001). Similar 6OH-PCB2:2OH-PCB2 ratios were found in our air samples and Aroclors, suggesting that Aroclors are a legacy source of OH-PCB2 congeners to the atmosphere and appear to be volatilizing proportionally to PCBs in Aroclors. Although degradation by the hydroxyl radical has been proposed as an efficient loss process for airborne PCBs, we found no evidence that this mechanism results in the formation of OH-PCB2 congeners.