Spatial and seasonal variations of biogenic tracer compounds in ambient PM10 and PM1 samples in Berlin, Germany

Abstract: PM10 and PM1 aerosol samples were collected between February and October, 2010 at three sites in Berlin that were characterized by different vegetation influences. The aim of the study was to determine the spatial and seasonal variations of several, mainly biogenic secondary and primary tracers in an urban area. Selected tracers including isoprene and α-pinene markers, fatty acids and levoglucosan were detected with GC-MS. The highest median concentrations, up to 45.1ngm−3, were found for the combustion product levoglucosan. The concentration range of the secondary compounds was 0.3ngm−3 for the isoprene markers 2-methyltetrols up to 35.7ngm−3 for malic acid. The occurrence of these compounds was mainly affected by the seasons, which could be described by three patterns. Whereas secondary compounds were mainly characterized by significantly higher concentrations during the warmer months, levoglucosan showed significantly higher concentrations during the colder months. No significant concentration differences between the two periods were rather observed for the primary compounds but also for the α-pinene degradation product pinonic acid. The secondary compounds and levoglucosan could be associated with the fine mode (particles with an aerodynamic diameter (AD)<1μm), while primary compounds are rather associated with the coarse mode (AD>1μm). Spatial variations were emphasized with a tendency toward higher concentrations for most compounds at sites that were influenced by vegetation, especially evident for the PM10 fraction. Besides concentration differences, spatial variations could also be described by differences in seasonal behavior and the size distribution, indicating major complexity in the composition of biogenic PM within the city of Berlin. [Copyright &y& Elsevier]