Aerosol contributions at an urban background site in Eastern Mediterranean - Potential source regions of PAHs in PM mass.

In this paper, two backward air mass trajectory-based models (Potential Source Contribution Function [PSCF] and Concentration Weighted Trajectory [CWT]) were combined, aiming to identify sources and factors defining the load of PM in the city of Limassol (Cyprus). The study also focused on the determination of atmospheric pathways enriching the aerosol phase of four carcinogenic Polycyclic Aromatic Hydrocarbons (PAHs): Benzo(a)pyrene (BaP), Benzo(a)anthracene (BaA), Benzo(b)fluoranthene (BbF) and Benzo(k)fluoranthene (BkF), in PM mass. The analysis was performed on a 0.5°·0.5° resolution grid for the two-year period 2011-2012. During cold seasons, regional airflows triggered the accumulation of locally produced PM, while the impact of dust plumes originated from deserts in NE Africa, Syria and the Middle East, was apparent on PM and principally on PM levels. On the contrary, within warm seasons, weaker dust PM contributions were detected in Limassol from areas in Egypt and Libya. Raised particulate-phase PAH concentrations in Limassol were clearly related to air parcels reaching Cyprus via continental areas. The use of outdated technologies for heating and transportation in Turkey and Syria, and fire events in central Turkey, are possible sources of exogenous PAHs throughout cold and warm period respectively. The influence of clean marine air masses dropped the levels of PAH compounds in all seasons.