Variations in Soot Concentrations in the Megalopolises of Beijing and Moscow.

The measurements of soot aerosol concentration in Moscow and Beijing in 2004–2010 are presented. The variability ranges of one-time soot concentrations in this period of time had been 0.1–77 μg/m³ in Beijing and 0.1–22 μg/m³ in Moscow. The seven-year average daytime soot concentration in Beijing is 2.5 times higher than in Moscow. The seasonal behavior of the soot concentration is more pronounced in Moscow: the soot concentration is 33% lower in summer than in winter, and only 13% lower in Beijing. Analysis of back trajectories of air mass transport and variations in soot concentration showed that the soot content in the atmosphere of Beijing significantly increases when air masses are transported from industrially developed regions south of Beijing. The air pollution by soot in Moscow predominantly decreases due to advection when air masses from northern regions come to Moscow. [ABSTRACT FROM AUTHOR]