Organic compounds in atmospheric aerosols from a Finnish coniferous forest

Atmospheric aerosol particles were collected with a high-volume sampler in a Finnish coniferous forest during the field campaign Quantification of Aerosol Nucleation in the European Boundary Layer (QUEST) in March–April 2003. Four chromatographic techniques were applied to characterise the organic composition of the samples, and to study variations in the concentrations of identified compounds. Among the nearly 160 organic compounds identified were n-alkanes, n-alkanals, n-alkan-2-ones, n-alkanols, n-alkanoic acids, n-alkenoic acids, dicarboxylic acids, polyaromatic hydrocarbons, hopanes, streranes, terpenes and terpenoids. The observed variations in the concentrations of certain compounds were mostly explained by ambient temperature. Comparison of days when atmospheric new particle formation took place with days when the formation did not occur, however, revealed higher concentrations of long-chain n-alkanes (> C22) and < C18 n-alkanoic acids on the particle formation days.