Free and combined L- and D-amino acids in Arctic aerosol

Aerosol samples were collected with a high-volume cascade impactor with a 10-day sampling frequency at the Gruvebadet observatory, close to Ny-Ålesund (Svalbard Islands). A total of 42 filters were analysed for free and combined amino acids, as they are key components of bio-aerosol. The main aim of this study was to determine how these compounds are distributed in size-segregated aerosols after short-range and long-range atmospheric transport and understand the possible sources of amino acids. The total load of free amino acids ranged from 2.0 to 10.8 pmol m-3, while combined amino acids ranged from 5.5 to 18.0 pmol m-3. Levoglucosan, methanesulfonate (MSA) and non-sea salt sulfate (nss-) were used as specific markers for biomass burning, and phytoplankton blooms and were used in comparison with the concentration of free amino acids to confirm potential emission sources. Back-trajectories analysis and factor analysis were used to describe the geographic origin of the air masses and to explain how biomass burning events and phytoplankton blooms may influenced the free amino acids concentration. Free and combined amino acids were mainly found in the fine aerosol fraction (<0.49 mm). This study provides the first investigation of free and combined L- and D-amino acids in Arctic atmospheric particulate matter.