Time Variations in the Composition of Atmospheric Aerosol in Moscow in Spring 2020

The results of an intensive complex experiment carried out from March 25 to May 3, 2020, to study the composition and time variability of urban aerosol in the atmosphere in the center of Moscow include data on daily mean concentrations of both РМ10 and РМ2.5 particles and 65 chemical elements. The concentrations of all components did not exceed the maximum permissible concentration (MPC) for residential areas. The exception was increased РМ10 concentrations recorded on March 27–29, when air masses from neighboring regions with biomass fires arrived in the city. The coefficients of correlation between values of the concentrations and enrichment factors of the elements confirmed the anthropogenic/local origin of some heavy metals (Cd, Sb, Pb, Se, Th) and the terrigenous/global origin of elements such as Mn, Mg, Zn, Co, Fe, Al, and Cr. The elements S, P, K, Na, Ca, Ni, Cu, Mo, Sn, W, Bi, and U, for which no significant correlation between their concentrations and enrichment factors has been found, apparently, have a mixed origin from both natural and anthropogenic sources competing with each other from day to day. The first studies of the weekly cycle of the relative elemental composition of surface aerosol in Moscow have shown the leading role of meteorological conditions (in particular, air pressure and humidity) in variations of aerosol pollution levels.