Measurement of Dry Deposition and Air-Water Exchange of Polycyclic Aromatic Hydrocarbons with the Water Surface Sampler

Recent work has shown that dry deposition and gas exchange of semivolatile organic compounds in the Great Lakes is important. However, there is no generally accepted method for collecting particulate dry deposition or gas exchange. In this work the Water Surface Sampler (WSS) was modified and used in combination with dry deposition plates to measure the particulate dry deposition and gas exchange of PAHs. Simultaneous dry deposition and ambient air samples were collected between June and October 1995 in Chicago, IL. Total (particulate + gas) fluxes were measured with the WSS, while particulate fluxes were measured with dry deposition plates. Average Σ14-PAH and particulate Σ14-PAH fluxes were 360 ± 146 μg/m2 d and 144 ± 60 μg/m2 d, respectively. Gas-phase fluxes, determined by subtracting the dry deposition plate fluxes (particulate) from WSS fluxes (particulate + gas), averaged 170 ± 72 μg/m2 d. The measured particulate dry deposition and gas exchange fluxes were substantially higher than those previousl...