Concentration and Gas-particle Partitioning of Atmospheric Polycyclic Aromatic Hydrocarbons in Relation to Monsoons

Abstract:

The atmospheric concentrations and gas-particle partitioning of polycyclic aromatic hydrocarbons (PAHs) were determined in the Hengchun Peninsula of southern Taiwan. The concentrations of total suspended particle (TSP) and total PAH (t-PAH; gas + particulate) ranged from 1.6 to 78.8 μg m^-3 and 430 to 4400 pg m^-3, respectively. The highest levels of t-PAH concentrations and particle-associated PAHs were found during the northeast (NE) monsoon season. Long-range transport and rainfall scavenging mechanisms could contribute to seasonal variations in TSP and t-PAH concentrations. Results from principal component analysis (PCA) indicated that air mass movement caused by the monsoon system was the main influence on atmospheric PAHs profiles and concentrations. Gas-particle partition coefficients (K_p) of PAHs were well-correlated with the sub-cooled liquid vapor pressures (P^o_L), suggesting that the gas-particle partition of PAHs follows the characteristic of PAHs. In addition, the partitioning of PAHs between gas and particle phases varied significantly between NE and SW monsoon seasons. This study sheds lights on the role of Asian monsoon regarding atmospheric transport of PAHs.