Organic Aerosol Processing During Winter Severe Haze Episodes in Beijing

Zhao, Jian; Qiu, Yanmei; Zhou, Wei; Xu, Weiqi; Wang, Junfeng; Zhang, Yingjie; Fu, Pingqing; Xie, Conghui; Wang, Qingqing; Du, Wei; Worsnop, Douglas R.; Canagaratna, Manjula R.; Zhou, Libo; Ge, Xinlei; Fu, Pingqing; Li, Jie; Wang, Zifa; Donahue, Neil M.; Sun, Yele

doi:10.1029/2019jd030832

Cited by 77 publications

(80 citation statements)

References 135 publications

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“…Such results are also supported by the large increase of non-volatile OA as elevated RH (Fig. S6), and the increases signal fraction of CHO + (m/z 29) in the mass spectra (7.2%-16.1%), a tracer ion related to aqueous processes (Zhao et al, 2019).…”

Section: Comparisons Between Volatile and Non-volatile Compoundssupporting

confidence: 57%

Organic aerosol volatility and viscosity in North China Plain: Contrast between summer and winter

Xu¹,

Chen²,

Qiu³

et al. 2020

Preprint

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Abstract. Volatility and viscosity have substantial impacts on gas-particle partitioning, formation and evolution of aerosol, and hence the predictions of aerosol related air quality and climate effects. Here aerosol volatility and viscosity at a rural site (Gucheng) and an urban site (Beijing) in North China Plain (NCP) in summer and winter were investigated by using a thermodenuder coupled with high resolution aerosol mass spectrometer. The effective saturation concentration (C*) of organic aerosol (OA) in summer was smaller than that in winter (0.55 μg m−3 vs. 0.71–0.75 μg m−3), indicating that OA in winter in NCP is more volatile due to enhanced primary emissions from coal combustion and biomass burning. The volatility distributions varied largely different among different OA factors. In particular, we found that hydrocarbon-like OA (HOA) contained more non-volatile compounds compared to coal combustion related OA. The more oxidized oxygenated OA (MO-OOA) showed overall lower volatility than less oxidized OOA (LO-OOA) in both summer and winter, yet the volatility of MO-OOA was found to be relative humidity (RH) dependent showing more volatile properties at higher RH. Our results demonstrated the different composition and chemical formation pathways of MO-OOA under different RH levels. The glass transition temperature (Tg) and viscosity of OA in summer and winter are estimated using the recently developed parameterization formula. Our results showed that the Tg of OA in summer in Beijing (291.5 K) was higher than that in winter (289.7–290.0 K), while it varied greatly among different OA factors. The viscosity suggested that OA existed mainly as solid in winter in Beijing, but as semi-solids in Beijing in summer and Gucheng in winter. These results have important implications that kinetically limited gas-particle partitioning may need to be considered when simulating secondary OA formation in NCP.

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Section: Comparisons Between Volatile and Non-volatile Compoundssupporting

confidence: 57%

Organic aerosol volatility and viscosity in North China Plain: Contrast between summer and winter

Xu¹,

Chen²,

Qiu³

et al. 2020

Preprint

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“…In particular, whether SOA materials condensed on BC particles have similar chemical characteristics to those externally mixed with BC particles 10 remains poorly understood. Previous observations in urban environments have reported that the mass spectral features of ambient OOA components identified by the PMF analysis were significantly different between the two co-located measurements even though their temporal variabilities strongly correlated to each other (Chen et al, 2018;Lee et al, 2017;Liu et al, 2019;Massoli et al, 2015;Wang et al, 2020;Xu et al, 2019;Zhao et al, 2019). Given our observations that vaporization scheme plays a critical role in the fragmentation process of oxygenated organic species,…”

Section: Insight Into Ambient Ooa Characteristicssupporting

confidence: 64%

Elemental analysis of Oxygenated Organic Coating on Black Carbon Particles using a Soot-Particle Aerosol Mass Spectrometer

Ma¹,

Rivellini²,

Cui³

et al. 2020

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Abstract. Chemical characterization of organic coatings is important to advance our understanding of the physio-chemical properties and environmental fate of black carbon (BC) particles. The soot-particle aerosol mass spectrometer (SP-AMS) has been utilized for this purpose in recent field studies. The laser vaporization (LV) scheme of SP-AMS can heat BC cores gradually until they are completely vaporized, during which organic coatings can be vaporized at temperatures lower than that of the thermal vaporizer (TV) used in a standard high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) that employs flash vaporization. This work investigates the effects of vaporization schemes on fragmentation and elemental analysis of known oxygenated organic species using three SP-AMS instruments. We show that LV can reduce fragmentation of organic molecules. Substantial enhancement of C2H3O+/CO2+ and C2H4O2+ signals was observed for most of the tested species when the LV scheme was used, suggesting that the observational frameworks based using HR-ToF-AMS field data may not be directly applicable for evaluating the chemical evolution of oxygenated organic aerosol (OOA) components coated on ambient BC particles. The uncertainties of H:C and O:C determined by the improved-ambient (I-A) method for both LV and TV approaches were similar, with scaling factors of 1.10 for H:C and 0.89 for O:C were determined to facilitate more direct comparisons between observations from the two vaporization schemes. Furthermore, the I-A method was updated based on the multilinear regression model for the LV scheme measurements. The updated parameters can reduce the relative errors of O:C from −26.3 % to 5.8 %, whereas the relative errors of H:C remain roughly the same. Applying the scaling factors and the updated parameters for the I-A method to ambient data, we found that even though the time series of OOA components determined by the LV and TV schemes are strongly correlated at the same location, OOA coatings were likely less oxygenated compared to those externally mixed with BC.

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“…Biomass burning, coal combustion, traffic, and dust are the key sources of PM (Sun et al, 2014a;Liu et al, 2018;Huang et al, 2014). Multiple studies have confirmed that biomass burning is an essential source of PM in urban Beijing (Gao et al, 2014;Sun et al, 2014a;Zheng et al, 2017). In this study, biomass burning and other solid fuel burning were identified as crucial sources of PM in not only urban but also rural areas of Beijing.…”

Section: Discussionmentioning

confidence: 66%

Simultaneous measurements of urban and rural particles in Beijing – Part 1: Chemical composition and mixing state

et al. 2020

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Abstract. Two single-particle aerosol mass spectrometers (SPAMSs) were deployed simultaneously at an urban and a rural site in Beijing during an intensive field campaign from 1 to 29 November 2016 to investigate the source and process of airborne particles in Beijing. In the first part of this research, we report the single-particle chemical composition, mixing state, and evolution at both sites. A total of 96 % and 98 % of collected particles were carbonaceous at the urban and rural sites, respectively. Five particle categories, including elemental carbon (EC), organic carbon (OC), internal-mixed EC and OC (ECOC), potassium-rich (K-rich), and metals, were observed at both sites. The categories were partitioned into particle types depending on different atmospheric processing stages. A total of 17 particle types were shared at both sites. In the urban area, nitrate-containing particle types, such as EC-Nit (Nit: nitrate) and ECOC-Nit, were enriched especially at night, sulfate-containing particles were transported when wind speed was high, and ECOC-Nit-Sul (Sul: sulfate) were mostly aged locally. In sum, these processed particles added up to 85.3 % in the urban areas. In the rural area, regional particles were abundant, but freshly emitted ECOC and OC had distinct patterns that were pronounced at cooking and heating times. Biomass burning, traffic, and coal burning were major sources of particulate matter (PM2.5) in both rural and urban areas. Moreover, particles from the steel industry located in the south were also identified. In summary, the chemical composition of urban and rural particle types was similar in Beijing; the urban particles were influenced significantly by rural processing and transport. The work is useful to understand the evolution of urban and rural particles in Beijing during winter.

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Organic Aerosol Processing During Winter Severe Haze Episodes in Beijing

Cited by 77 publications

References 135 publications

Organic aerosol volatility and viscosity in North China Plain: Contrast between summer and winter

Organic aerosol volatility and viscosity in North China Plain: Contrast between summer and winter

Elemental analysis of Oxygenated Organic Coating on Black Carbon Particles using a Soot-Particle Aerosol Mass Spectrometer

Simultaneous measurements of urban and rural particles in Beijing – Part 1: Chemical composition and mixing state

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