ИСТИНА

High density of population and multi-profile activities in megacities objectively lead to large-scale ecological impact emphasizing the need to assess the sources of air pollution. Spring is the season when complementary impacts of agriculture fires/biomass burning are increasing significantly in accordance to biogenic activity, which can be observed at the same time. In the complex situation of the plurality of anthropogenic emissions, an important research task remains for the megacity environment to identify the contributions of the major sources including biomass burning and biogenic, through aerosol composition analyses. This study reports the evaluation of air the quality in the urban background of Moscow megacity in spring 2017. This period was characterized by significant changes of air temperature, mass advection, and solar radiation. Synergistic coupling of PM10 mass concentration, light absorbing properties, aerosol composition and meteorological measurements has been performed in urban background at the Meteorological Observatory of the Moscow State University (MSU). Organic and elemental carbon (OC, EC) as well as 76 organic compounds like alkanes, polycyclic aromatic hydrocarbons (PAHs), oxidized PAHs (o-PAHs), hopans and anhydrosugars, polyols, primary- and secondary saccharides were quantified to describe the carbonaceous particle fraction. Thirteen ions characterize the inorganic composition. Angstrom Absorption Exponent (AAE) parametrization estimates the relative contributions of agriculture fires and domestic biomass burning around the city to urban aerosol composition dominated by fossil fuel combustion. Combining attentive analytical chemical and statistical approaches, representative chemical compounds are able to describe the highest quantity of variability, evaluated together with the highest analytical validity of the chemical compounds. Comprehensive principal component analyses (PCA) supported by chemical markers, meteorological parameters and air mass transportation analyses is able to highlight the emission sources from fossil fuel combustion, heavy-duty transport, air mass transportation from agriculture fires and domestic activity. Secondary organic and inorganic aerosol formation and photochemical processes occur in the period of increasing biogenic activity.