AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Long-term Volatility Measurements of Submicron Atmospheric Aerosol in Boreal Forest
SILJA HÄKKINEN, Mikko Äijälä, Katrianne Lehtipalo, Heikki Junninen, John Backman, Aki Virkkula, Tuomo Nieminen, Mika Vestenius, Hannele Hakola, Mikael Ehn, Douglas Worsnop, Markku Kulmala, Tuukka Petäjä, Ilona Riipinen, University of Helsinki
Abstract Number: 52 Working Group: Remote and Regional Atmospheric Aerosols
Abstract The volatility of atmospheric submicron aerosol particles was investigated in a boreal forest site in Hyytiälä, Finland, in order to get information on aerosol chemical properties and composition. Measurements were performed continuously between January 2008 and May 2010. Ambient sample air was heated step-wise to six temperatures ranging from 80 to 280 degrees Celsius and the total mass concentration of aerosol particles was determined from the measured particle number size distribution before and after heating. On average 19% of the total aerosol mass stayed in the condensed or solid phase even after heating the aerosol to 280 degrees Celsius. Black carbon explained 55 to 90% of the non-volatile mass. Especially during colder months noticeable amount of non-volatile material, something else than black carbon, was observed. Using additional information on ambient meteorological conditions and air mass trajectories, as well as results from aerosol mass spectrometry (AMS) the chemical composition of the non-volatile residual and its seasonal behavior was further examined. However, no single explaining factor was found. During winter and spring months the non-volatile aerosol residual had a significant positive correlation with pollutant trace gases, such as carbon monoxide, and polycyclic aromatic hydrocarbons (PAH). This indicates a strong anthropogenic influence on the non-volatile aerosol residual. From campaign-based AMS data it was seen that during fall 2008 aerosol particles were relatively more non-volatile when the aerosol mass fraction of organic nitrate and organics was high compared to the sulfate contribution. Thus, the existence of very low-volatile organic compounds can be speculated.