Biogenic contributions to the chemical composition of airborne particles in a coniferous forest in Germany

Airborne particles in and above the canopy of a middle European spruce forest were investigated in summer 2001 and in day/night rhythm in summer 2002 near Waldstein site (Fichtelgebirge, Germany). The particles were size-segregated collected and analyzed for main components (inorganic ions, elemental and organic carbon) as well as oxalic acid and alkanes. A mass closure for the chemical composition including water was performed successfully for both years. For analysis of other organic compounds high volume (HV) samplers were used in order to obtain more particle mass. The HV filter particles were measured with GC/MS after extraction and derivatisation. The highest concentrations were found for the sugars and the dicarboxylic acids. Four terpene acids, pinonaldehyde and isoprene oxidation products were detected. Differences between day and night samples were found for pinonaldehyde (night: 13.7 ng m−3; day: 2.7 ng m−3), for pinic acid (night: 3.2 ng m−3; day: 9.5 ng m−3) and also for the 2-methyltetrols (night: 4.0 ng m−3; day: 8 ng m−3). The detected terpene and isoprene oxidation products account only for a small part of the measured organic carbon content of particles. In all cases oxalic acid accounts for the major fraction of the speciated organic carbon. The origin of the main components like inorganic ions, OC, and EC is associated with the origin of air masses.