Gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs) in an urban traffic site in Eskisehir, Turkey

Abstract

Gas and particle-phase ambient air samples were collected at a traffic site in Eskisehir over a six-month period between January and October 2006. Gas/particle concentrations of 15 PAHs were determined by analyzing integrated glass fiber and polyurethane foam samples. On average, 66% of the total concentrations of PAHs were found in the gas-phase in heating and 69% in the non-heating period samples. Heating period PAH concentrations were found to be 7 to 8 times greater than concentrations in non-heating period samples. Multiple linear regression analysis was carried out to determine the effect of meteorological parameters on measured individual PAH concentrations. Temperature, wind speed and wind direction explained 43% (dibenzo[a,h]anthracene and benzo[a]pyrene) to 78% (phenanthrene) of the variability in atmospheric PAH concentrations. Results of the multiple linear regression analysis indicated that temperature and wind speed were statistically significant factors for the measured concentrations of PAHs. Gas-particle partitioning coefficients, (K-p) and particle-phase fractions (Phi) of PAHs, were correlated with supercooled vapor pressures (P-L(o)). Application of non-linear fitting for Phi versus log P-L(o) plots was found to be more robust than linear logarithmic regressions of log K-p versus log P-L(o) plots. Particle-phase fractions (Phi) for each PAH were also calculated using octanol-air and soot-air partitioning models. Soot model resulted better predictions of Phi for fluorene, phenanthrene, anthracene, fluoranthene and pyrene. Both two models yielded very similar particle-phase fractions having very close results to experimentally obtained Phi values for the rest of PAHs measured