Concentrations and ratio of dissolved and suspended forms of metals and metalloids (MMs) in snow cover and their deposition rates from the atmosphere in the western part of Moscow were studied. Forms of MMs were separated using a filter with pore diameter of 0.45 μm; their concentrations were measured by ICP-MS and ICP-AES methods. Anthropogenic impact in Moscow caused a significant increase in dust load (2–7 times), concentration of solid particles in snow cover (2–5 times), and mineralization of snow meltwater (5–18 times) compared to the background level. Urban snow contains Sn, Ti, Bi, Al, W, Fe, Pb, V, Cr, Rb, Mo, Mn, As, Co, Cu, Ba, Sb, Mg mainly in suspended form, and Ca and Na in dissolved form. The role of suspended MMs in the city significantly increases compared to the background region due to high dust load, usage of de-icing salts, and the change of acidic background conditions to alkaline ones. Anthropogenic emissions are the main sources of suspended Ca, W, Co, V, Sr, Ti, Mg, Na, Mo, Zn, Fe, Sb, and Cu in the snow cover of traffic zone. These elements’ concentrations in roadside snow cover exceed the background values more than 25 times. The highest concentrations and deposition rates of MMs in the snow of Moscow are localized near the large and medium roads.

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This article summarizes the data of the chemical composition and the acidity of the seasonal snow precipitation for the cold periods 1999-2006 (n=180), 2010-2013 (n=82) and 2018-2019 (n=18) in different parts of Moscow. Major ions content was measured, such as SO42-, НСO3-, Cl-, NO3-, Са2+, Mg2+, Na+, K+ and NH4+, also pH and sum of ions (mg/L) were measured. During the 2018-2019 season, snowpack samples were taken twice at 4 sites in Moscow: two in the North-East Administrative Okrug (NEAO) near the road and in the park at the distance of 3 km from each other, and two in the South- Western Administrative Okrug (SWAO) and in the Western Administrative Okrug (WAO) near the road and in the park at the distance of 6 km from each other. Samples were taken with a break of 5 days to determine the dynamics of the chemical composition within the beginning of the snow-melting. In each pair of sampling sites there was one that is located in the park and one located near the road. This experiment showed a slight variability of the chemical composition of snow during 5 days under the influence of the new snowfall. In general, there is a trend of changing the composition of snow from calcium carbonate to calcium chloride, which is mainly connected to the use of anti-icing reagents; for the same reason, the areas that are closer to the roads are the most polluted.

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