Articles | Volume 17, issue 22
Research article
20 Nov 2017
Research article |  | 20 Nov 2017

Particulate trimethylamine in the summertime Canadian high Arctic lower troposphere

Franziska Köllner, Johannes Schneider, Megan D. Willis, Thomas Klimach, Frank Helleis, Heiko Bozem, Daniel Kunkel, Peter Hoor, Julia Burkart, W. Richard Leaitch, Amir A. Aliabadi, Jonathan P. D. Abbatt, Andreas B. Herber, and Stephan Borrmann

Abstract. Size-resolved and vertical profile measurements of single particle chemical composition (sampling altitude range 50–3000 m) were conducted in July 2014 in the Canadian high Arctic during an aircraft-based measurement campaign (NETCARE 2014). We deployed the single particle laser ablation aerosol mass spectrometer ALABAMA (vacuum aerodynamic diameter range approximately 200–1000 nm) to identify different particle types and their mixing states. On the basis of the single particle analysis, we found that a significant fraction (23 %) of all analyzed particles (in total: 7412) contained trimethylamine (TMA). Two main pieces of evidence suggest that these TMA-containing particles originated from emissions within the Arctic boundary layer. First, the maximum fraction of particulate TMA occurred in the Arctic boundary layer. Second, compared to particles observed aloft, TMA particles were smaller and less oxidized. Further, air mass history analysis, associated wind data and comparison with measurements of methanesulfonic acid give evidence of a marine-biogenic influence on particulate TMA. Moreover, the external mixture of TMA-containing particles and sodium and chloride (Na ∕ Cl-) containing particles, together with low wind speeds, suggests particulate TMA results from secondary conversion of precursor gases released by the ocean. In contrast to TMA-containing particles originating from inner-Arctic sources, particles with biomass burning markers (such as levoglucosan and potassium) showed a higher fraction at higher altitudes, indicating long-range transport as their source. Our measurements highlight the importance of natural, marine inner-Arctic sources for composition and growth of summertime Arctic aerosol.

Short summary
We conducted aircraft-based single particle chemical composition measurements in the Canadian high Arctic during summer. Our results provide evidence for a marine-biogenic influence on secondary formation of particulate trimethylamine in the Arctic boundary layer. Understanding emission sources and further processes controlling aerosol number concentration and chemical composition in the pristine Arctic summer is crucial for modeling future climate in the area.
Final-revised paper