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

There are different approaches to determine dry deposition velocities (Vd) and mass transfer coefficients (KG) 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 KG 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/m2 d, while the mean gas-phase PAH flux was 5 060±4 260 ng/m2 d. The ratio between fluxes and air concentration values was used in calculation of Vd and KG. The average calculated Vd and KG 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. KG was also calculated using some models reported in the literature and models developed using the MWSS. The predicted KG determined by models developed using the MWSS was 0.59±0.02 cm/s showing a close agreement with the experimentally measured values.