Dry Deposition of Polycyclic Aromatic Hydrocarbons in Ambient Air

Diurnal and seasonal variability in size-dependent atmospheric deposition fluxes of polycyclic aromatic hydrocarbons in an urban center

“…Contrary to the results in the present study, monotonically increasing V values of individual PAHs with decreasing sub-cooled liquid vapor pressures were obtained in previous studies, which was attributed to the enrichment of low molecular weight PAHs in the gaseous phase (McVeety and Hites, 1988;Sheu et al, 1996); however, contradicting results were reported from Greece (Terzi and Samara, 2005). The difference may be partially explained by different meteorological conditions that lead to differences in the dispersion, distribution and deposition of atmospheric pollutants (Lang et al, 2002) equilibrium partitioning between the gaseous and particulate phases leads to differences in PAH size distributions, as discussed above.…”

“…It seems that the dry deposition of PAHs in Guangzhou is predominated by dry particle deposition. This result is similar to those obtained at various sites (urban, industrial, rural sites) in Tainan and Taichung of Taiwan (Sheu et al, 1996;Fang et al, 2004), but different from those observed at the urban and rural sites of western Greece (Terzi and Samara, 2005). However, if a higher dry deposition velocity of 0.005 m s À1 is used (which is also possible as shown in a few previous studies (Poor et al, 2004)), then the dry deposition of gaseous PAHs can be as important as particle PAHs dry deposition.…”

“…Dry deposition of PAHs in the gaseous phase is mainly caused by diffusion. Dry deposition velocity of gaseous PAHs is usually lower than that of particle-bound PAHs, and reported values have large uncertainties (Lee, 1991;Sheu et al, 1996;Fang et al, 2004;Poor et al, 2004). If a conservative value of 2 Â 10 À4 m s À1 (Lee, 1991) is used for the dry deposition velocity of gaseous PAHs in the present study, the mean dry deposition fluxes of gaseous PAHs in summer is estimated at 0.51 AE 0.18 (100 m) and 0.27 AE 0.11 (150 m) pg m À2 s À1 in daytime and 0.40 AE 0.16 (100 m) and 0.51 AE 0.22 (150 m) pg m À2 s À1 at night, while those in winter were 0.41 AE 0.43 (100 m) and 0.16 AE 0.15 (150 m) pg m À2 s À1 in daytime and were 0.50 AE 0.45 (100 m) and 0.15 AE 0.18 (150 m) pg m À2 s À1 at night.…”

“…Dry deposition fluxes of semivolatile organic compounds (SVOCs), substantially influenced by particle size and meteorological conditions (Sheu et al, 1996), have been extensively measured worldwide. Surrogate receptors (mostly polyvinyl chloride plates smeared with silicon grease and water-filled platters) (Holsen and Noll, 1992;Sheu et al, 1996;Franz et al, 1998;Odabasi et al, 1998;Shahin et al, 1999;Tasdemir and Esen, 2007) and automated wet/dry deposition collectors (Feely et al, 1985;Golomb et al, 1997;Terzi and Samara, 2005) have been used to measure dry deposition fluxes. However, surrogate receptors seldom reasonably represent natural surfaces; therefore the results cannot be extrapolated to natural deposition with confidence.…”

Calculated respiratory exposure to indoor size-fractioned polycyclic aromatic hydrocarbons in an urban environment

“…Polycyclic aromatic hydrocarbons (PAHs) are a group of pollutants typically found in urban areas, and are principally generated from a variety of incomplete combustion processes (Sheu et al, 1996), e.g., fossil fuel combustion, incineration, coking, and cooking. High levels of atmospheric PAHs have been shown to induce elevated lung cancer risk (Boström et al, 2002), a major cause of death in China (Jiang et al, 2008).…”