Journal of Aerosol Science 144 (2020) 105544 Available online 25 February 2020 0021-8502/© 2020 Elsevier Ltd. All rights reserved. Seasonal fuctuation of activity size distribution of 7 Be, 210 Pb, and 210 Poradionuclides in urban aerosols Magdalena Długosz-Lisiecka a, * , Henryk Bem b a Lodz University of Technology, Faculty of Chemistry, Institute of Applied Radiation Chemistry, Wr� oblewskiego 15, 90-924, L� od� z, Poland b The President Stanislaw Wojciechowski State University of Applied Sciences in Kalisz, 62-800, Kalisz, Nowy � Swiat 4 St, Poland A R T I C L E INFO Keywords: AMAD MMAD Radionuclides in surface air Anthropogenic emission of Po-210 PCA ABSTRACT The activity size distributions of cosmogenic 7 Be and the longer living radon progenies 210 Pb and 210 Po in urban aerosols were measured for summers and winters from, 2014 to the end of 2017. The average seasonal activity median aerosol diameters (AMADs) and mass median aerosol di- ameters (MMADs) calculated for summer ranged from 0.329 μm to 0.733 μm and were ordered AMAD Be-7, <AMAD Pb-210, <AMAD Po-210, <MMAD, whereas for winter, these values were from 0.420 μm to 0.538 μm but were differently ordered:AMAD Po-210, <AMAD Be-7, <AMAD Pb- 210, <MMAD. The prevailing occurrence of 210 Po in particles of the smallest diameter during winter can be explained by the remarkable additional anthropogenic emission of this radionuclide from coal combustion. This was confrmed with principal component analysis (PCA) of the AMAD data. 1. Introduction Cosmogenic 7 Be formed in the upper troposphere is increasingly associated with submicron-aerosol particles called Aitken nuclei, which have diameters of ~0.015 μm and participate in the formation and growth of accumulation mode aerosols during their vertical transport to the ground level atmosphere (Papastefanou, 2009, Winkler, Dietl, Frank, & Tschiersch, 1998). Therefore, the AMAD method for estimating the residence time of atmospheric aerosols is based on the aerosol particle growth rate (Papastefanou, 2006; Papastefanou & Ioannidou, 1998; Talpos & Cuculeanu, 1997; Ho, Lee, Chung, Choi, & Lee, 2006; Ioannidou & Paatero, 2014). Gaseous 222 Rn (radon) escaping from the soil produce in the lower atmosphere the shorter living decay products of 218 Po (3 min), 214 Pb (26.8 min), 214 Bi (19.0 min), and 214 Po (0.16 ms), which are in partial equilibrium with their mother radionuclide, as well as a series of longer living products: 210 Pb (22.3 years), 210 Bi (5 days), and 210 Po (138 days) (Baskaran, 2011). These radionuclides (except for radon) are readily absorbed on the surface of aerosol particles, and while the activity of 210 Pb does not change much since its half-life is 22.3 years, the activity of 210 Bi and 210 Po grow during the residence time of aerosol particles in the air before their dry or wet deposition on the surface of soil (Papastefanou, 2006). The initial concentrations of 210 Pb and 210 Po depend not only on the near-surface air activity concentrations of the mother radionuclide 222 Rn, but also on the vertical transport of air masses, rate of wet and dry deposition of aerosols, and other natural (volcano eruptions) (Baskaran, 2011) or anthropogenic sources (fossil fuel com- bustion, smelting or metal foundries, cement production, ect.). Due to the high vapor pressure, Po and Pb eagerly evaporate from the combustion (smelting) area and condense on accessible surfaces, especially on fne fy ashes leaving the chimney. Increase of the * Corresponding author. E-mail address: mdlugosz@mitr.p.lodz.pl (M. Długosz-Lisiecka). Contents lists available at ScienceDirect Journal of Aerosol Science journal homepage: http://www.elsevier.com/locate/jaerosci https://doi.org/10.1016/j.jaerosci.2020.105544 Received 28 October 2019; Received in revised form 27 January 2020; Accepted 23 February 2020