ИСТИНА

Particulate matter (PM) pollution may originate from a variety of sources, both primary and secondary. The identification of major sources responsible for the observed particulate pollution levels is crucial for the development of effective mitigation measures and the protection of public health, especially in megacities, where there is high population density and the various socioeconomic activities result in numerous emission sources. The aim of the study is to identify the main emission sources of PM10 in the European largest megacity and quantify their contribution to the observed concentration levels. It should be noted that this is the first source apportionment study performed for the Moscow megacity where central heating system using gas is operated during the cold seasons and biomass does not used in residential sector, despite of other European megacities. 24hr PM10 samples were collected during spring of 2018, and autumn and winter of 2019-2020 at the Aerosol Complex of Moscow State University, classified as urban background site. The samples were analysed for (i) major and trace elements by ICP-MS, ICP-AES and XRF, (ii) organic and elemental carbon by thermo-optical transmittance method, and (iii) major ionic species by IC. PM10 mass concentrations were measured by TEOM 1400a. PM10 chemical composition database was used for the source apportionment through the application of Positive Matrix Factorization (EPA PMF 5.0 model). The input database consisted of 128 samples/days and 28 chemical components. PM10 concentrations were higher during spring (29 ± 16 μg/m3), followed by autumn (20 ± 9 μg/m3) and winter (14 ± 6 μg/m3). This trend was also observed in major PM components, such as OC, EC, SO42- and crustal elements. The best solution was identified by best-fit criteria and considering the physical meaning of the extracted factors, it corresponds to six sources, namely: Vehicular traffic, Road salting, City dust, Industrial emissions, Biomass Burning, and Secondary aerosol formation. Vehicular traffic is identified by the low OC/EC ratio in the source profile (equal to 2.0) and typical traffic tracers, such as Zn, Ba and Sb. Road salting relates to Na+ and Cl-; 62% of total Na+ mass and 86% of total Cl- mass is apportioned to this factor (Fig. 1). City . dust contains crustal elements (Al, Ca, Ti, Fe), together with anthropogenic ones, such as carbonaceous, Cu, Zn and Pb. This source profile is in a good agreement with measured profiles of road dust in Moscow (Vlasov et al., 2021). Industrial profile contains EC, OC, Ni, Cu and Cr with biggest impact. Biomass burning is identified by the presence of K+, and OC and EC, with a high OC/EC ratio (8.3), it is probably address the impact of the Moscow region around a city. Secondary aerosol formation source contains mainly SO42-, NO3-, NH4+ ,and OC.