Variability of submicron aerosol observed at a rural site in Beijing in the summer of 2006

Abstract

Ground‐based measurements of aerosol and trace gases were conducted at a rural site in Beijing in the summer of 2006 as a part of the Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing 2006). The size‐resolved chemical composition of submicron aerosol was measured using an Aerodyne quadrupole aerosol mass spectrometer (AMS). The data obtained from 15 August to 10 September 2006 are presented. Meteorological analysis shows that the measurement period can be characterized as a cycle of low wind speed periods over the course of a few days (stagnant periods) followed by rapid advection of clean air from the north/northwest mostly due to passage of a midlatitude cyclone. Mass concentrations of total measured aerosol with diameters less than 1 μm (total PM1), which is defined as the sum of elemental carbon and nonrefractory components measured by the AMS, were highly variable, ranging from ∼2 to ∼100 μg m−3. Large variability of the PM1 composition and drastic changes in the sulfate (SO42−) size distribution were observed to be associated with the cycle of stagnant periods and advection of clean air, indicating that both chemical and physical properties of aerosols were significantly altered on a time scale of a few days. We have found the dominance of organic aerosol at lower total PM1 mass loadings and that of SO42− at higher mass loadings, which may have important implications for the PM control strategy in Beijing. Possible factors affecting the evolution of the mass concentration and size distribution of SO42− are discussed.

Technical Note: The application of an improved gas and aerosol collector for ambient air pollutants in China

“…The operation conditions, detection mode and data processing of the AMS were same as those introduced by Huang et al (2011). The parameter of collection efficiency (CE) of 0.5 was applied since the sampled air was dried through a Nafion (MD-110, Perma Pure, USA) (Takegawa et al, 2009). …”

“…Therefore, a direct comparison between these two instruments with different cutoff sizes was made in this study. Sea salt particles which can be easily captured and measured by the GAC-IC cannot be measured by the AMS (Takegawa et al, 2009). We estimated non-sea salt (nss) Cl − based on the GAC-IC data assuming that all of the measured Na + was originated from sodium chloride (NaCl) in sea salt.…”

Development of a parameterization of black carbon aging for use in general circulation models

“…Note that these initial parameters cover concentrations of chemical species from polluted urban air (e.g., BC = 10.0 µg m −3 and SO 2 = 10.0 parts per billion by volume (ppbv) at the surface in Beijing; Han et al, 2009;Takegawa et al, 2009) to free tropospheric air (e.g., BC = 0.1 µg m −3 and SO 2 = 0.1 ppbv in the free troposphere over the western Pacific; Russo et al, 2003;Oshima et al, 2012). The calculations were conducted using hourly photolysis rates for equinox at midlatitudes, although results obtained in this study can be applied irrespective of latitude and season (see Sects.…”

Simultaneous measurements of particle number size distributions at ground level and 260 m on a meteorological tower in urban Beijing, China

“…Fine particles can significantly reduce atmospheric visibility, exert harmful effects on public health, and even have potential impacts on regional and global climate. As a result, extensive efforts have been devoted to characterize the sources, formation mechanisms, and evolution processes of aerosol particles in recent years (Ma et al, 2012;Takegawa et al, 2009;Sun et al, , 2014Sun et al, , 2016b. Among these studies, particle number concentrations are one of the greatest concerns because particles can rapidly grow from a few nanometers to tens and even hundreds of nanometers in a short time, and hence play a significant role in haze formation (Guo et al, 2014).…”