[Size Distributions of Different Carbonaceous Components in Ambient Aerosols].

It is important to obtain the size distribution of carbonaceous components in aerosols for studying the formation and transformation mechanisms and radiation characteristics of regional aerosols. However, only a few studies on the size distribution of aerosol carbonaceous fractions have been conducted in Beijing. In this study, a Micro-Orifice Uniform Deposit Impactor (MOUDI)-120 sampler was used to collect size-resolved aerosol samples in three seasons in Beijing, and the concentrations of different types of carbonaceous fractions were analyzed.

[Size Distributions of Water-soluble Components in Ambient Aerosol of Beijing].

A micro-orifice uniform deposit impactor (MOUDI-122) was used to collect ambient aerosol at an urban site in Beijing in both winter and summer from 2016 to 2017. The water-soluble components, including ions and water-soluble organic carbon (WSOC) were analyzed. The characteristics of concentrations and size distributions for water-soluble components under different seasons and pollution conditions were determined.

[Impact of Mountain-Valley Wind Circulation on Typical Cases of Air Pollution in Beijing].

The impact of mountain-valley wind circulation on the typical examples of pollution was analyzed through the selected pollution process, combining with the hourly PM concentrations and meteorological data in Haidian, Shangdianzi and Lishuiqiao in Autumn and Winter from 2013 to 2015, and also the data of Tower of atmospheric, wind profile of Haidian and automatic meteorological stations in the same period. The analysis showed that the average wind speed of valley wind was greater than that of the mountain wind, and they both would be "broken" during the conversion time in the mountain-valley wind days. In contrast with the mountain wind, the average duration of valley wind in autumn was longer than that in winter, and the start time of valley wind in autumn was earlier than the same wind in winter; influenced by the topography of Beijing area, the direction boundary of the transformation between mountain-valley wind was northeast-southwest.

[A Case Study on the Rapid Cleaned Away of PM₂.₅ Pollution in Beijing Related with BL Jet and Its Mechanism].

The concentration of PM₂.₅ decreased very rapidly from 18:00 to 23:00 on 17th Mar. 2015 in Beijing area.

[Atmospheric nitrogen deposition in urban area of Beijing].

Using ion exchange resin columns method, atmospheric nitrogen deposition was observed in the urban area of Beijing from March to September in 2009. The average value of atmospheric nitrate nitrogen deposition was 40.59 mg x m(-2) and that of atmospheric sulfite nitrogen deposition was 14.