Characterization of submicron aerosols during a month of serious pollution in Beijing, 2013

Abstract

Abstract. In January 2013, Beijing experienced several serious haze events. To achieve a better understanding of the characteristics, sources and processes of aerosols during this month, an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed at an urban site between 1 January and 1 February 2013 to obtain the size-resolved chemical composition of non-refractory submicron particles (NR-PM1). During this period, the mean measured NR-PM1 mass concentration was 89.3 ± 85.6 μg m−3, and it peaked at 423 μg m−3. Positive matrix factorization (PMF) differentiated the organic aerosol into five components, including a highly oxidized, low-volatility oxygenated organic aerosol (LV-OOA), a less oxidized, semi-volatile oxygenated OA (SV-OOA), a coal combustion OA (CCOA), a cooking-related OA (COA), and a hydrocarbon-like OA (HOA), which on average accounted for 28%, 26%, 15%, 20% and 11% of the total organic mass, respectively. A detailed comparison between the polluted days and unpolluted days found many interesting results. First, the organic fraction was the most important NR-PM1 species during the unpolluted days (58%), while inorganic species were dominant on polluted days (59%). The OA composition also experienced a significant change; it was dominated by primary OA (POA), including COA, HOA and CCOA, on unpolluted days. The contribution of secondary OA (SOA) increased from 35% to 63% between unpolluted and polluted days. Second, meteorological effects played an important role in the heavy pollution in this month and differed significantly between the two types of days. The temperature and relative humidity (RH) were all increased on polluted days and the wind speed and air pressure were decreased. Third, the diurnal variation trend in NR-PM1 species and OA components showed some differences between the two types of days, and the OA was more highly oxidized on polluted days. Fourth, the effects of air masses were significantly different between the two types of days; air was mainly transported from contaminated areas on the polluted days. The comparison also found that the aerosol was more acidic on polluted days. Additionally, the variation trends of the mass concentration and mass fractions of NR-PM1 species and OA components were more dramatic when the NR-PM1 mass loading was at a higher level. The serious pollution observed in this month can be attributed to the synergy of unfavorable meteorological factors, the transport of air masses from high-pollution areas, emission by local sources, and other factors.

Influence of Intense secondary aerosol formation and long range transport on aerosol chemistry and properties in the Seoul Metropolitan Area during spring time: Results from KORUS-AQ

“…8d) 20 and high f44 (14 %) (Fig. S18a), which are in similar range as those previously reported for aged 21 and highly oxidized OA, including LV-OOAs, from various locations (e.g., Hayes et al, 22 2013;Mohr et al, 2012;Zhang et al, 2014;Ng et al, 2010). The diurnal profile of LV-OOA was 23 different than SV-OOA as well, showing a gradual increase from 8:00 till late afternoon despite a 24 rising PBL height (Fig.…”

“…PM 10 pollution in urban areas is commonly associated with elevated anthropogenic emissions, stagnant 11 meteorological conditions, and regional transport of pollutants from upwind locations (Cao et al, 12 2012;Guo et al, 2014;Sun et al, 2014;Zheng et al, 2015;Molina, 2004;Young et al, 2015). 13…”

Effect of the pollution control measures on PM2.5 during the 2015 China Victory Day Parade: Implication from water-soluble ions and sulfur isotope

“…The contribution from coal combustion to PM 2.5 of Beijing is very significant (R.J. . The air mass from the south and southeast of Beijing passed the Hebei province, one of the largest coalconsuming provinces in China, which leads to an increase in PM 2.5 concentrations in Beijing air (Sun et al, 2010;Zhang et al, 2014). Still, the PM 2.5 concentrations during the period from August 29 to August 31, 2015 and on September 4, 2015 were lower than 50 mg/m 3 .…”

Record Heavy PM_2.5 Air Pollution over China in January 2013: Vertical and Horizontal Dimensions

“…Hence, heavy PM 2.5 pollution in China has become a critical environmental problem for daily life, human health, regional/international traffic, and trans-boundary PM 2.5 transport to other countries. Observational studies of the PM 2.5 pollution in China were reported by Zhang et al (2014), Sun et al (2014), Wang et al (2014) and Yonemochi et al (2013). However, most of the observational studies were based on ground-based chemical composition observations.…”