Particle size distribution of organic primary and secondary aerosol constituents in urban, background marine, and forest atmosphere

Abstract

Polynuclear aromatic hydrocarbons (PAHs), n‐alkanes, n‐alkanals, n‐alkanols, saturated and unsaturated carboxylic acids, α, ω‐dicarboxylic acids, and carbonyl and carboxylic photooxidation products of monoteprenes were determined in particle‐sized aerosols of urban (Heraclion, Island of Crete, Greece), background marine (Island of Crete, Greece), and forest (Northern Greece and Portugal) atmospheres. The n‐alkanes were mostly associated with fine particles in the urban and forest aerosol, and their mass mean aerodynamic diameter (MMAD) calculated over the whole size range (total MMAD) was 0.45 μm and 0.63 μm, respectively. In the background marine aerosol, n‐alkanes were more evenly distributed, and their MMAD was 2.00 μm, because of physical changes occurring during their long‐range transport. Similar observations have been done for PAHs and n‐alkanals. Conversely, the most biogenic compound class, namely n‐alkanols, were evenly associated in the urban, background marine, and forest aerosol, between fine and coarse particles, and their corresponding total MMAD was 2.45, 2.69, and 1.67 μm, respectively. The total MMAD of n‐alkanoic acids was 0.71, 0.62, and 0.91 μm in the urban, background marine, and forest aerosol, respectively. Several compounds associated with photochemical reactions in the atmosphere were detected in urban marine and forests aerosol in the fine and ultrafine fraction, showing the low total MMAD (0.28–0.77 μm) in all aerosol types.