A Prototype Passive Air Sampler for Measuring Dry Deposition of Polycyclic Aromatic Hydrocarbons

The passive dry deposition (Pas-DD) collector is presented as a tool for estimating atmospheric loadings (dry deposition fluxes or maps) for polycyclic aromatic hydrocarbons (PAHs) and other semivolatile compounds. Pas-DD collectors based on a parallel plate design were codeployed with conventional polyurethane foam (PUF) disk passive air samplers (PAS) in outdoor urban air over different seasons. Two configurations of sampling media (PUF only vs stacked glass fiber filter on PUF) were used. For both samplers, a higher level of accumulation of PAHs was observed when only the PUF disk was used as the sampling medium. The Pas-DD collector and the PAS accumulated gas-phase PAHs (dry gaseous deposition component) to a similar extent. For the higher-molecular weight PAHs that are associated with particles, the Pas-DD collector was enriched relative to the PAS. Dry deposition velocities derived from the Pas-DD collector were approximately 0.16 cm/s for gas-phase PAHs and up to 0.8 cm/s for particle-phase PAHs.