Gas-particle partitioning and seasonal variation of polycyclic aromatic hydrocarbons in the atmosphere of Zonguldak, Turkey.

Atmospheric concentrations and gas-particle partition coefficients were determined for polycyclic aromatic hydrocarbons (PAHs) in the atmosphere of Zonguldak, Turkey between May 2007 and April 2008. Total concentrations of PAHs ranged from 0.52ngm(-3) to 636ngm(-3) in the particle phase and from 5.60ngm(-3) to 725ngm(-3) in the gas phase. The annual mean concentrations of PAHs in the particle and gas phase were found to be 114ngm(-3) and 184ngm(-3), respectively. Significant seasonal variations of particle and gas phase PAH concentrations were observed with higher levels during cold period. The distribution of PAHs between the particle and gas phase was investigated and it was found that three ring PAHs were associated primarily with the gas phase, four ring PAHs were distributed almost equally between the two phases and five and six ring PAHs were mainly associated with the particle phase. Gas-particle partition coefficients (K(p)) of PAHs have been calculated and correlated with their subcooled liquid vapor pressures (P(L)º). The slopes (m(r)) varied from -0.63 to -0.23 were far from the theoretical value (-1) due to the short distance between the sampling point and the emission sources. The relationships between temperature and gas phase partial pressures of PAHs were examined using the Clausius-Clapeyron equation and the obtained positive slopes indicated that PAH concentrations increased with decreasing air temperature as a result of high dominance of local emissions.