Daily Variations In Wet Deposition And Washout Rates Of Potentially Toxic Elements In Moscow During Spring Season

Abstract

For the first time, the wet deposition and washout rates of soluble forms of potentially toxic elements (PTEs) were estimated in rains during the spring AeroRadCity experiment in Moscow. Rains are an important factor in reducing atmospheric pollution with PTEs in Moscow. Due to the resuspension of contaminated particles of road dust and urban soils, industrial and traffic impact, waste and biomass burning, rainwater is highly enriched in Sb, Pb, Se, Cd, and S, and less enriched in P, Ba, As, W, Mn, Sn, Na, Co, Ni, and Be. Significant wet deposition (μg/m2 per event) and washout rates (μg/m2 per hour) of PTEs were revealed during the public holidays in May which corresponded to the elevated aerosol content due to predominant air advection from southern and south-western regions in this period. During continuous rains, the level of PTEs wet deposition sharply decreases on the second and subsequent days due to the active below-cloud washout of aerosols during the initial precipitation events. We show that the length of the dry period and aerosol content before the onset of rain determines the amount of solid particles in rainwater, which leads to an increase in rainwater pH, and strongly affects wet deposition and washout rates of PTEs of mainly anthropogenic origin (W, Zn, Bi, Cd, Sb, Ni, B, S, K, and Cu). At the same time rainfall intensity contributes to an increase in wet deposition and washout rates of Se, As, B, Cu, Sb, S, Cd, Ba, Rb, and K. The obtained results provide a better understanding of atmospheric deposition processes and can be useful in assessing the urban environmental quality.

Elemental Composition of PM2.5 and PM10 and Health Risks Assessment in the Industrial Districts of Chelyabinsk, South Ural Region, Russia

“…Chelyabinsk is one of the snowiest cities in the Russian Federation. The decrease of PM concentration in winter can partially be explained by the “wash-out” effect, as the first snowfall typically happens in October and are lasting throughout the winter [ 46 , 47 , 48 ]. Snow grains to moderate snow has been reported from January–March and October–December of 2020 ( Figure S1b ).…”

“…The substantial increase in PM 2.5 and PM 10 levels from March to August at Station 2, compared to Stations 1 and 3, could be due to dust resuspension of the nearby slag dump caused by windy dry weather. During the autumn-winter period rains [ 46 ] and snow cover [ 47 , 48 ] significantly reduced dust episodes and the levels at Station 2 is comparable to that of Stations 1 and 3. The PM 2.5 and PM 10 concentrations observed during the spring-summer period of 2020 at Station 3 were substantially lower than at Station 2 and markedly lower than at Station 1.…”