Characterization of free amino acids, bacteria and fungi in size-segregated atmospheric aerosols in boreal forest: seasonal patterns, abundances and size distributions
- 1Department of Chemistry, P.O. Box 55, University of Helsinki, 00014 Helsinki, Finland
- 2Division of Microbiology and Biotechnology, Department of Food and Environmental Sciences, P.O. Box 56, University of Helsinki, 00014 Helsinki, Finland
- 3Department of Forest Sciences, P.O. Box 27, University of Helsinki, 00014 Helsinki, Finland
Abstract. Primary biological aerosol particles (PBAPs) are ubiquitous in the atmosphere and constitute ∼ 30 % of atmospheric aerosol particle mass in sizes > 1 µm. PBAP components, such as bacteria, fungi and pollen, may affect the climate by acting as cloud-active particles, thus having an effect on cloud and precipitation formation processes. In this study, size-segregated aerosol samples (< 1.0, 1–2.5, 2.5–10 and > 10 µm) were collected in boreal forest (Hyytiälä, Finland) during a 9-month period covering all seasons and analysed for free amino acids (FAAs), DNA concentration and microorganism (bacteria, Pseudomonas and fungi). Measurements were performed using tandem mass spectrometry, spectrophotometry and qPCR, respectively. Meteorological parameters and statistical analysis were used to study their atmospheric implication for results. Distinct annual patterns of PBAP components were observed, late spring and autumn being seasons of dominant occurrence. Elevated abundances of FAAs and bacteria were observed during the local pollen season, whereas fungi were observed at the highest level during autumn. Meteorological parameters such as air and soil temperature, radiation and rainfall were observed to possess a close relationship with PBAP abundances on an annual scale.