| Abstract
| - Air samples were collected simultaneously at three sitesdownwind of Lake Ontario and at a control site near LakeErie from March to July of 1999. The Lake Erie site(Stockton, NY) had PCB concentrations similar to ruralIntegrated Atmospheric Deposition Network (IADN) samplingsites across the Great Lakes, exhibited limited seasonalvariation, and approximates regional background. Samplestaken along Lake Ontario's southeastern shore (RiceCreek and Sterling, NY) had elevated PCB concentrationsaveraging ∼1 ng/m3 and were more chlorinated thanair collected at IADN sites and at Stockton. Air samplesfrom Potsdam (∼75 km inland) had similar concentrationsbut were less chlorinated. Clausius−Clapeyron plotsrevealed a strong correlation between PCB fugacity andtemperature near Lake Ontario; however, the extent ofchlorination of the air samples rules out volatilization fromthe lake as a major source. It is hypothesized thatvolatilization from local surfaces, enriched in higherchlorinated congeners by meteorological or geographicfactors, drives both the concentration and composition ofairborne PCBs along Lake Ontario's southeastern shore.
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