Wintertime Aerosol Chemistry in Sub-Arctic Urban Air

• Main Authors: Sueper, Donna, Jimenez, Jose L., Worsnop, Douglas R., Carbone, Samara, Aurela, Minna, Saarnio, Karri, Saarikoski, Sanna, Timonen, Hilkka, Frey, Anna, Ulbrich, Ingrid M., Kulmala, Markku, Hillamo, Risto E.
• Format: Text
• Language: unknown
• Published: Taylor & Francis 2014
• Subjects: Uncategorized; Arctic
• Online Access: https://dx.doi.org/10.6084/m9.figshare.963449; https://tandf.figshare.com/articles/journal_contribution/Wintertime_Aerosol_Chemistry_in_Sub_Arctic_Urban_Air/963449

Measurements of submicron particulate matter (PM) were performed at an urban background station, in Helsinki, Finland during wintertime to investigate the chemical characteristics and sources of PM 1 . The PM 1 was dominated by sulfate and organics. The source apportionment indicated that organic aerosol (OA) was a mixture from local sources (biomass burning (BBOA), traffic, coffee roaster (CROA)), secondary compounds formed in local wintertime conditions (nitrogen containing OA (NOA), semivolatile oxygenated OA (SV-OOA), and regional and long-range transported compounds (low volatile oxygenated OA, LV-OOA). BBOA was dominated by the fragments C 2 H 4 O 2 + and C 3 H 4 O 2 + (m/z 60.021 and 73.029) from levoglucosan, or other similar sugar components, comprising on average 32% of the BBOA mass concentration. The ratio between fragments C 2 H 4 O 2 + /C 3 H 4 O 2 + was significantly lower for CROA (=1.1) when compared to BBOA (=2.1), indicating that they consisted of different sugar compounds. In addition, a component containing substantial amount of nitrogen compounds (NOA) was observed in a sub-arctic region for the first time. The NOA contribution to OA ranged from 1% to 29% and elevated concentrations were observed when ambient relative humidity was high and the visibility low. Low solar radiation and temperature in wintertime were observed to influence the oxidation of compounds. A change in aerosol composition, with an increase of LV-OOA and decrease in BBOA, SV-OOA and NOA was noticed during the transition from wintertime to springtime. Size distribution measurements with high-time resolution enabled chemical characterization of externally mixed aerosol from different sources. Aged regional long-range transported aerosols were dominant at around 0.5 μm (vacuum aerodynamic diameter), whereas traffic and CROA emissions dominated at around 120 nm. Copyright 2014 American Association for Aerosol Research