Wintertime secondary organic aerosol formation in Beijing–Tianjin–Hebei (BTH): contributions of HONO sources and heterogeneous reactions

Li, Xing; Wu, Jiarui; Elser, Miriam; Tong, Shengrui; Liu, Suixin; Li, Xia; Liü, Lang; Cao, Junji; Zhou, Jiaqi; Haddad, Imad El; Huang, Ru‐Jin; Ge, Maofa; Tie, Xuexi; Prévôt, Andrê S. H.; Li, Guohui

doi:10.5194/acp-19-2343-2019

Cited by 89 publications

(68 citation statements)

References 74 publications

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“…However, aqueous-phase formation of SOA has also been considered an important pathway during some pollution events in, e.g., Beijing, Shijiazhuang and Baoji Wang et al, 2017;Huang et al, 2019). The formation of less-oxidized oxygenated OA (LO-OOA) and moreoxidized oxygenated OA (MO-OOA) in Baoji seemed to be significantly influenced by aqueous-phase chemistry during the period of low atmospheric oxidative capacity , while in another study Xu et al (2017) suggested that aqueous-phase processing has a dominant impact on MO-OOA formation but that photochemical oxidation is the dominant pathway for LO-OOA formation in Beijing. It is still unclear whether aqueous-phase processing plays a key role in haze development and what the mechanisms are.…”

Section: Introductionmentioning

confidence: 91%

“…Compared to primary aerosol that is relatively well constrained in terms of the emission sources, secondary aerosol is still not well understood, likely due to its variable precursors, complex formation and atmospheric transformation processes mediated by meteorological conditions Petäjä et al, 2016;Tie et al, 2017;Xu et al, 2017). A number of studies have investigated the formation and aging processes of secondary aerosol (Takegawa et al, 2009;Huang et al, 2014Huang et al, , 2019Sun et al, 2014Sun et al, , 2016Wang et al, 2016;Duan et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

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Summertime and wintertime atmospheric processes of secondary aerosol in Beijing

Duan

Huang

et al. 2020

Atmos. Chem. Phys.

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Abstract. Secondary aerosol constitutes a large fraction of fine particles in urban air of China. However, its formation mechanisms and atmospheric processes remain largely uncertain despite considerable study in recent years. To elucidate the seasonal variations in fine-particle composition and secondary aerosol formation, an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM), combined with other online instruments, was used to characterize the sub-micrometer particulate matter (diameter < 1 µm, PM1) in Beijing during summer and winter 2015. Our results suggest that photochemical oxidation was the major pathway for sulfate formation during summer, whereas aqueous-phase reaction became an important process for sulfate formation during winter. High concentrations of nitrate (17 % of the PM1 mass) were found during winter, explained by enhanced gas-to-particle partitioning at low temperature, while high nitrate concentrations (19 %) were also observed under the conditions of high relative humidity (RH) during summer, likely due to the hydrophilic property of NH4NO3 and hydrolysis of N2O5. As for organic aerosol (OA) sources, secondary OA (SOA) dominated the OA mass (74 %) during summer, while the SOA contribution decreased to 39 % during winter due to enhanced primary emissions in the heating season. In terms of the SOA formation, photochemical oxidation perhaps played an important role for summertime oxygenated OA (OOA) formation and less-oxidized wintertime OOA (LO-OOA) formation. The wintertime more-oxidized OOA (MO-OOA) showed a good correlation with aerosol liquid water content (ALWC), indicating a more important contribution of aqueous-phase processing over photochemical production to MO-OOA. Meanwhile, the dependence of LO-OOA and the mass ratio of LO-OOA to MO-OOA on atmospheric oxidative tracer (i.e., Ox) both degraded when RH was greater than 60 %, suggesting that RH or aerosol liquid water may also affect LO-OOA formation.

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Summertime and wintertime atmospheric processes of secondary aerosol in Beijing

Duan

Huang

et al. 2020

Atmos. Chem. Phys.

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“…However, the attenuation of incoming solar radiation caused by the ALW also decreases the photolysis rates, being unfavorable for photochemical activities and lowering the atmospheric oxidation capability (AOC). Field measurements show that a large fraction of SA in PM 2.5 has been observed in the NCP during wintertime (Sun et al, 2013;Guo et al, 2014;Xu et al, 2015). Therefore, decreased AOC generally does not facilitate the SA formation, particularly with regards to SOA and nitrate, to partially counteract the PM 2.5 enhancement caused by the ALW.…”

Section: Relationship Between Rh and Near-surface Pm 25 Concentrationsmentioning

confidence: 99%

Is water vapor a key player of the wintertime haze in North China Plain?

Bei

et al. 2019

Atmos. Chem. Phys.

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Abstract. Water vapor has been proposed to amplify the severe haze pollution in China by enhancing the aerosol–radiation feedback (ARF). Observations have revealed that the near-surface PM2.5 concentrations ([PM2.5]) generally exhibit an increasing trend with relative humidity (RH) in the North China Plain (NCP) during 2015 wintertime, indicating that the aerosol liquid water (ALW) caused by hygroscopic growth could play an important role in the PM2.5 formation and accumulation. Simulations during a persistent and heavy haze pollution episode from 5 December 2015 to 4 January 2016 in the NCP were conducted using the WRF-Chem Model to comprehensively quantify contributions of the ALW effect to near-surface [PM2.5]. The WRF-Chem Model generally performs reasonably well in simulating the temporal variations in RH against measurements in the NCP. The factor separation approach (FSA) was used to evaluate the contribution of the ALW effect on the ARF, photochemistry, and heterogeneous reactions to [PM2.5]. The ALW not only augments particle sizes to enhance aerosol backward scattering but also increases the effective radius to favor aerosol forward scattering. The contribution of the ALW effect on the ARF and photochemistry to near-surface [PM2.5] is not significant, being generally within 1.0 µg m−3 on average in the NCP during the episode. Serving as an excellent substrate for heterogeneous reactions, the ALW substantially enhances the secondary aerosol (SA) formation, with an average contribution of 71 %, 10 %, 26 %, and 48 % to near-surface sulfate, nitrate, ammonium, and secondary organic aerosol concentrations. Nevertheless, the SA enhancement due to the ALW decreases the aerosol optical depth and increases the effective radius to weaken the ARF, reducing near-surface primary aerosols. The contribution of the ALW total effect to near-surface [PM2.5] is 17.5 % on average, which is overwhelmingly dominated by enhanced SA. Model sensitivities also show that when the RH is less than 80 %, the ALW progressively increases near-surface [PM2.5] but commences to decrease when the RH exceeds 80 % due to the high occurrence frequencies of precipitation.

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“…Organic aerosol (OA) is a key component of PM 2.5 in ambient air, constituting of 20 %-90 % of the PM 2.5 mass concentration (Kanakidou et al, 2005;Zhang et al, 2007). Previous studies have confirmed a large mass fraction of OA in ambient PM 2.5 in various Chinese cities.…”

Section: Introductionmentioning

confidence: 99%

Secondary organic aerosol enhanced by increasing atmospheric oxidizing capacity in Beijing–Tianjin–Hebei (BTH), China

et al. 2019

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Abstract. The implementation of the Air Pollution Prevention and Control Action Plan in China since 2013 has profoundly altered the ambient pollutants in the Beijing–Tianjin–Hebei (BTH) region. Here we show observations of substantially increased O3 concentrations (about 30 %) and a remarkable increase in the ratio of organic carbon (OC) to elemental carbon (EC) in BTH during the autumn from 2013 to 2015, revealing an enhancement in atmospheric oxidizing capacity (AOC) and secondary organic aerosol (SOA) formation. To explore the impacts of increasing AOC on the SOA formation, a severe air pollution episode from 3 to 8 October 2015 with high O3 and PM2.5 concentrations is simulated using the WRF-Chem model. The model performs reasonably well in simulating the spatial distributions of PM2.5 and O3 concentrations over BTH and the temporal variations in PM2.5, O3, NO2, OC, and EC concentrations in Beijing compared to measurements. Sensitivity studies show that the change in AOC substantially influences the SOA formation in BTH. A sensitivity case characterized by a 31 % O3 decrease (or 36 % OH decrease) reduces the SOA level by about 30 % and the SOA fraction in total organic aerosol by 17 % (from 0.52 to 0.43, dimensionless). Spatially, the SOA decrease caused by reduced AOC is ubiquitous in BTH, but the spatial relationship between SOA concentrations and the AOC is dependent on the SOA precursor distribution. Studies on SOA formation pathways further show that when the AOC is reduced, the SOA from oxidation and partitioning of semivolatile primary organic aerosol (POA) and co-emitted intermediate volatile organic compounds (IVOCs) decreases remarkably, followed by those from anthropogenic and biogenic volatile organic compounds (VOCs). Meanwhile, the SOA decrease in the irreversible uptake of glyoxal and methylglyoxal on the aerosol surfaces is negligible.

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Wintertime secondary organic aerosol formation in Beijing–Tianjin–Hebei (BTH): contributions of HONO sources and heterogeneous reactions

Cited by 89 publications

References 74 publications

Summertime and wintertime atmospheric processes of secondary aerosol in Beijing

Summertime and wintertime atmospheric processes of secondary aerosol in Beijing

Is water vapor a key player of the wintertime haze in North China Plain?

Secondary organic aerosol enhanced by increasing atmospheric oxidizing capacity in Beijing–Tianjin–Hebei (BTH), China

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