The gas-and particle-phase polycyclic aromatic hydrocarbons (PAHs) were collected from the air of Liaodong Bay in May and August to investigate their occurrence and gas/particle distribution. The 24 PAHs were analyzed for gas-and particle-phase samples, and the concentrations of total gas-and particle-phase PAHs were found to be 28.8 ng·m-3 and 24.0 ng·m-3, respectively. The concentrations of the gas-phase PAHs were higher in August than in May, and the concentrations of the particle-phase PAHs were higher in May than in August. The low molecular weight PAHs were mainly distributed in the gas-phase, and the high molecular weight PAHs were mainly distributed in the particle-phase; the medium molecular weight PAHs were more easily affected by the environmental conditions than the low and high molecular weight PAHs. The value of Kp increased with an increase in the molecular weight. The slopes m for regressed lgKp-lgPL and lgKp-lgKOA plots were -0.35 and 0.37, deviated from -1 and+1 for the equilibrium states of gas/particle partitioning. The equilibrium states of the lgKp-lgKOA, lgKp-lgPL, and soot-air models were applied; the predicted results of the 5-ring PAHs fitted well with the field measure results. The predicted results of the soot-air model were much closer to the field measure results than the results of the lgKP-lgKOA and lgKP-lgPL models; compared to their heavier counterparts, the low and medium molecular weight PAHs were influenced to a greater extent by soot.
Keywords: Liaodong Bay; PAHs; atmosphere; distribution; gas-particle partitioning.