Physical and chemical characterization of urban winter-time aerosols by mobile measurements in Helsinki, Finland

Liisa Pirjola, Jarkko V. Niemi, Sanna Saarikoski, Minna Aurela, Joonas Enroth, Samara Carbone, Karri Saarnio, Heino Kuuluvainen, Anu Kousa, Topi Rönkkö, Risto Hillamo

    Research output: Contribution to journalArticleScientificpeer-review

    23 Citations (Scopus)
    45 Downloads (Pure)


    A two-week measurement campaign by a mobile laboratory van was performed in urban environments in the Helsinki metropolitan area, Finland, in winter 2012, to obtain a comprehensive view on aerosol properties and sources. The abundances and physico-chemical properties of particles varied strongly in time and space, depending on the main sources of aerosols. Four major types of winter aerosol were recognized: 1) clean background aerosol with low particle number (Ntot) and lung deposited surface area (LDSA) concentrations due to marine air flows from the Atlantic Ocean; 2) long-range transported (LRT) pollution aerosol due to air flows from eastern Europe where the particles were characterized by the high contribution of oxygenated organic aerosol (OOA) and inorganic species, particularly sulphate, but low BC contribution, and their size distribution possessed an additional accumulation mode; 3) fresh smoke plumes from residential wood combustion in suburban small houses, these particles were characterized by high biomass burning organic aerosol (BBOA) and black carbon (BC) concentrations; and 4) fresh emissions from traffic while driving on busy streets in the city centre and on the highways during morning rush hours. This aerosol was characterized by high concentration of Ntot, LDSA, small particles in the nucleation mode, as well as high hydrocarbon-like organic aerosol (HOA) and BC concentrations. In general, secondary components (OOA, NO3, NH4, and SO4) dominated the PM1 chemical composition during the LRT episode accounting for 70–80% of the PM1 mass, whereas fresh primary emissions (BC, HOA and BBOA) dominated the local traffic and wood burning emissions. The major individual particle types observed with electron microscopy analysis (TEM/EDX) were mainly related to residential wood combustion (K/S/C-rich, soot, other C-rich particles), traffic (soot, Si/Al-rich, Fe-rich), heavy fuel oil combustion in heat plants or ships (S with V-Ni-Fe), LRT pollutants (S/C-rich secondary particles) and sea salt (Na/Cl-rich). Tar balls from wood combustion were also observed, especially (∼5%) during the LRT pollution episode.

    Original languageEnglish
    Pages (from-to)60-75
    Number of pages16
    JournalAtmospheric Environment
    Publication statusPublished - 1 Jun 2017
    Publication typeA1 Journal article-refereed


    • AMS
    • Black carbon
    • Mobile laboratory
    • Size distribution
    • Traffic
    • Wood burning

    Publication forum classification

    • Publication forum level 1

    ASJC Scopus subject areas

    • Environmental Science(all)
    • Atmospheric Science


    Dive into the research topics of 'Physical and chemical characterization of urban winter-time aerosols by mobile measurements in Helsinki, Finland'. Together they form a unique fingerprint.

    Cite this