Determination of mass transfer rates and deposition levels of polycyclic aromatic hydrocarbons (PAHs) using a modified water surface sampler

Abstract

There are different approaches to determine dry deposition velocities (V-d) and mass transfer coefficients (K-G) of individual polycyclic aromatic hydrocarbons (PAHs). A modified water surface sampler (MWSS) and a high volume air sampler were concurrently used to determine Vd and K-G in this study. Ambient air and deposition samples were collected from August 2004 to May 2005 in Bursa, Turkey. The mean particle-phase dry deposition flux of PAHs was 890 +/- 520 ng/m(2) d, while the mean gas-phase PAH flux was 5 060 +/- 4 260 ng/m(2) d. The ratio between fluxes and air concentration values was used in calculation of V-d and K-G. The average calculated V-d and K-G values for PAH compounds were 0.52 +/- 0.36 cm/s and 0.69 +/- 0.41 cm/s, respectively. Despite the fluctuation on seasonal atmospheric concentrations due to regional sources and meteorological conditions, there was no significant difference on deposition velocities and mass transfer rates. K-G was also calculated using some models reported in the literature and models developed using the MWSS. The predicted K-G determined by models developed using the MWSS was 0.59 +/- 0.02 cm/s showing a close agreement with the experimentally measured values.