Characteristics of aerosol size distributions and new particle formation in the summer in Beijing

Abstract

[1] The Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing-2006) were mainly focused on the influence of the regional aerosol on the air pollution in Beijing. The urban aerosol was characterized in detail. The particle size distributions were also compared to those measured at a regional site (Yufa) approximately 50 km south of the urban site at Peking University (PKU). At PKU, total particle number and volume concentrations were (1.8 ± 0.8) Â 10 4 cm À3 and 83.5 ± 57.9 mm 3 cm À3 , respectively. Days in three consecutive summers of 2004, 2005, and 2006 were classified as polluted days with PM 10 over 150 mg m À3 and nonpolluted days with lower PM 10 . On nonpolluted days, particle number size distributions showed a maximum at about 60 nm with Aitken mode particles dominating number concentration. On polluted days, the contribution of accumulation mode particles increased, shifting the maximum of the number size distribution to over 80 nm. On polluted days with stagnant meteorological conditions, secondary aerosol dominated, with SO 4 2À , NO 3 À , and NH 4 + accounting for over 60% of accumulation mode particle mass. Particle number size distributions at both sites were similar. Number and volume concentrations of total particles at Yufa were 6% and 12% lower, respectively; those of accumulation mode particles were 2% and 15% lower. This means that air pollution in Beijing is mainly a regional problem. The regional accumulation mode particles are a metric for assessing the air quality since they influence most the visibility and total mass concentration. Their number and volume concentrations on polluted days were 5 Â 10 3 cm À3 and 30 mm 3 cm À3 , respectively. Five new particle formation (NPF) events with continuous smooth growth were observed at both PKU and Yufa during CAREBeijing-2006. These NPF events are regional or semiregional. Growth rates at PKU ranged from 1.2 to 5.6 nm h À1 , and formation rates ranged from 1.

Evaluation on the role of sulfuric acid in the mechanisms of new particle formation for Beijing case

“…The frequency of the NPF event (26 %) is higher than our previous studies in the same period of 2004-2007 (11 %-20 %) (Wu et al, 2007;Yue et al, 2009). In total, 22 NPF Fig.…”

Characteristics of concentrations and chemical compositions for PM<sub>2.5</sub> in the region of Beijing, Tianjin, and Hebei, China

“…Some studies have focused on the concentrations, correlations, sources or formation of some specific species (such as inorganic ions, carbonaceous components, or organic matters) of PM 2.5 in Beijing (Yao et al, 2002;Dan et al, 2004;Huang et al, 2006;Wang et al, 2009;Pathak et al, 2009;Ianniello et al, 2011). In addition, the size distributions of aerosol chemical species Cheng et al, 2009;Guo et al, 2010;Li et al, 2012), aerosol number concentrations or new particle formation processes Yue et al 2009Yue et al , 2011Shen et al, 2011;Zhang et al, 2011;Gao et al, 2012), and aerosol optical characteristics or mixing state (Cheng et al, 2009;Deng et al, 2011;Ma et al, 2011Ma et al, , 2012Chen et al, 2012) have also been discussed for Beijing and the surrounding region.…”

Observations of New Particle Formation, Subsequent Growth and Shrinkage during Summertime in Beijing

“…The growth rate ranged from 3.2-10.6 nm h -1 , which was higher than that in Hyytiälä (3.8 nm h -1 on average) and Helsinki (3.0 nm h -1 on average) (Hussein et al, 2008). It was also a little higher than that of 2006 (1.2 to 5.6 nm h -1 ) (Yue et al, 2009), probably indicating that the clean atmospheric condition may favor the growth of newly formed particles.…”

“…Owing to the emission control measures, the concentration of atmospheric particles measured in summertime of 2008 had experienced a significant decrease compared to that of 2006 (Yue et al, 2009). The measured total particle number was (6.4 ± 2.9) × 10 3 cm -3 , lower than that in summertime of 2006, (1.8 ± 0.8) × 10 4 cm -3 , although there could be a underestimation due to the limitation of minimum detection size of WPS.…”

“…NPF events during that period in Beijing were observed by several studies for investigating secondary aerosol formation, sulfuric acid promoting NPF, as well as the role of low-volatility organic vapors in NPF (Yue et al, 2010;Wang et al, 2011;Zhang et al, 2011;Gao et al, 2012;Wang et al, 2015). Characteristics of aerosol size distribution and NPF in absence of emission control measures in the summertime of 2006 in Beijing had been studied (Yue et al, 2009).…”