Аннотация:The process of airborne dust deposition connects soils with the atmosphere and other components of the city environment. Solid atmospheric fallouts are usually mentioned in the context of pollution assessments. However, such fallouts from the atmosphere actually include very diverse solid components that are deposited on the surface of soils. Our long-term study on the composition of solid atmospheric fallouts was conducted over several summer seasons in the city of Moscow at the some places of soil studies. Airborne dust deposits within recreational and roadside zones were sampled into plastic containers. Laboratory analyses of dust and soil samples included thefollowing: scanning electron microscopy (in conjunction with energy dispersive x-ray spectroscopy), micromorphology (thin sections) and chemical tests. It was revealed that dust deposition intensity significantly varied between different study sites. Low rates within the urban environment were similar to the background (suburban) dust deposition rate of 2.5 g/m2/year,but high rates within the city exceeded the background rate value by one or two orders of magnitude, with the maximal observed rate of 1.7 g/m2/day. Mean dust deposition rates at our study sites varied from 10 to 50 g/m2 /year, which broadly corresponded to the overall mean of 33 g/m2/year in Moscow (Achkasov et al., 2008). Thestudied dust samples were generally similar in their composition, with abundant quantities of microscopic particles of building materials, especially in samples taken near buildings. Dust aggregates with salt cementation, microplastics, textile fibres, fungal hyphae and fragments of faeces were common in samples from different study sites. Roadside dust deposits also included asphalt concrete particles and thin films ofhydrocarbons. Dust deposits within recreational zones were enriched in organic residues, pollen grains and aeroplankton organisms. According to our previous study (Prokof’eva et al., 2014), diagnostic horizons of urban soils (Urbic horizons) develop as a result of the pedogenic transformation of organogenic and mineral of natural and artificial substrates, simultaneously with the surface deposition of these materials including airborne solids. Microscopicartefacts found in dust samples in the present study were similar to common artefacts in Urbic horizons. Thus, solid atmospheric fallouts contribute low quantities, but a high diversity of materials to the upper horizons of urban soils. The composition of airborne dust includes aeroplankton, pollutants and alkaline substances, e.g., particles of building materials. Deposition of airborne dust can result in such soil properties as high contents of hydrocarbons, heavy metals and organic matter, neutral and alkaline pH, etc. Apparently, solid atmospheric fallouts provide for a direction of evolving to geochemical uniformity of all modern urban soilswithin the city.This work was supported by the Russian Foundation for Basic Research (project no. 19-05-50093,“micromir”»: field work and collection of samples, determination of soil properties and their interpretation) and State task no. 0148-2019-0006: development of approaches to the microscopy studies of fallouts and their microanalysis).[1] Аchkаsоv А.I., Bаshаrkеvich I.L., Varavа К.V., Sамаyеv S.B. (2006). Snow cover pollution by icing-reducing reagents. Prospect ofGeological Environment Control 9-10,132–137 in Russian[2] Prokof’eva T.V., Gerasimova M.I., Bezuglova O.S., Bakhmatova K.A., Gol’eva A.A., Gorbov S.N., Zharikova E.A., Matinyan N.N.,Nakvasina E.N., Sivtseva N.E. (2014). Inclusion of soils and soil-like bodies of urban territories into the Russian soil classification system.Eurasian Soil Science 47-10, 959–967
