Measurement report: Receptor modelling for source identification of urban fine and coarse particulate matter using hourly elemental composition

Abstract

Abstract. Elemental composition of the fine (PM2.5) and coarse (PM2.5-10) fraction of atmospheric particulate matter was measured at hourly time resolution by the use of a “streaker” sampler during a winter period at a Central European urban background site in Warsaw, Poland. A combination of multivariate (Positive Matrix Factorization), wind- (Conditional Probability Function) and trajectory-based (Cluster Analysis) receptor models, was applied for source apportionment. It allowed for identification of 5 similar sources in both fractions, including sulfates, soil dust, road salt, traffic- and industry-related sources. Another 2 sources, i.e., Cl-rich and wood and waste combustion, were identified in the fine fraction solely. In the fine fraction, aged sulfate aerosol related with emissions from solid fuel combustion in the residential sector located outside the city was the largest contributing source to fine elemental mass (44\u2009%), while traffic-related sources, including soil dust mixed with road dust, road dust, as well as exhaust and non-exhaust traffic emissions, had the biggest contribution in the coarse elemental mass (together accounting for 83\u2009%). Regional transport of aged aerosols and more local impact of the rest of identified sources played a crucial role in aerosol formation over the city. In addition, 2 intensive Saharan dust outbreaks were registered on 18th February and 8th March 2016. Both episodes were characterized by long-range transport of dust at 1 500\u2009m and 3 000\u2009m over Warsaw, as well as the concentrations of the soil component being 7 (up to 3.5\u2009µg\u2009m−3) and 6 (up to 6.1\u2009µg\u2009m−3) times higher than the mean concentrations observed during non-episodes days (0.5\u2009µg\u2009m−3 and 1.1\u2009µg\u2009m−3) in the fine and coarse fraction, respectively. The set of receptor models applied to the high time resolution data allowed to follow in detail the daily evolution of the aerosol elemental composition and to identify distinct sources contributing to the concentrations of different PM fractions, as well as revealed “multi-faces” of some elements, having diverse origin in the fine and coarse fraction. The hourly resolution of meteorological conditions and air mass back trajectories empower to follow transport pathways of the aerosol as well.