Molecular Distributions of Diacids, Oxoacids, and
            α
            ‐Dicarbonyls in Summer‐ and Winter‐Time Fine Aerosols From Tianjin, North China: Emissions From Combustion Sources and Aqueous Phase Secondary Formation

Abstract. For the first time in the North China Plain (NCP), we investigated the seasonal variations of submicron particles (NR-PM1) and its chemical composition at a background mountain station using Aerodyne high-resolution time-of-flight aerosol mass spectrometry (HR-ToF-AMS). The averaged NR-PM1 were highest in autumn (15.1 μg m−3) and lowest in summer (12.4 μg m−3), with the abundance of more nitrate in spring (34 %), winter (31 %), and autumn (34 %), and elevated organics (40 %) and sulfate (38 %) proportion in summer. The submicron particles were almost neutralized by excess ammonium in all four seasons except summer, when the aerosol particles appeared to be slightly acidic. The size distribution of all PM1 species showed a consistent accumulation mode peaked at approximately 600–800 nm (dva), indicating the highly aged and internally mixed nature of the background aerosols, which further supported by the source appointment using multilinear engine (ME-2) and significant contributions of aged secondary organic aerosol (SOA) in organic aerosol (OA) were resolved in all seasons (> 77 %), especially in summer (95 %). The oxidation degree and evolution process of OAs in the four seasons were further investigated, and enhanced carbon oxidation state (−0.45–0.10), O / C (0.54–0.75) and OM / OC (1.86–2.13) ratios compared with urban studies were observed, with the highest oxidation degree of which appeared in summer, likely due to the relatively stronger photochemical processing which dominated the processes of both less oxidized OA (LO-OOA) and more oxidized OA (MO-OOA) formations. Aqueous-phase processing also contributed to the SOA formation but prevailed in autumn and winter and the role of which to MO-OOA and LO-OOA also varied in different seasons. In addition, compared with the urban atmosphere, LO-OOA formation in the background atmosphere exhibited more regional characteristics, as photochemical and aqueous-phase processing enhanced during the transport in summer and autumn, respectively. Furthermore, the backward trajectories analysis showed that higher submicron particles were associated with air mass for short distance transported from the southern regions in four seasons, while the long-range transport from Inner Mongolia (west and north regions) also contributed to the summer particle pollutions in the background areas of NCP. Our results illustrate the background particles in NCP are influenced significantly by aging processing and transport, and the more neutralized state of submicron particles with the abundance of nitrate compared with those in the background atmosphere in southern and western China, highlighting the regional reductions in emissions of nitrogen oxide and ammonia are critical for remedying the increased occurrence of nitrate-dominated haze event in the NCP.

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Secondary Formation of Aerosols Under Typical High‐Humidity Conditions in Wintertime Sichuan Basin, China: A Contrast to the North China Plain

Journal of Geophysical Research Atmospheres ◽

10.1029/2021jd034560 ◽

2021 ◽

Vol 126 (10) ◽

Author(s):

Yujue Wang ◽

Min Hu ◽

Wei Hu ◽

Jing Zheng ◽

Hongya Niu ◽

...

Keyword(s):

Sichuan Basin ◽

North China Plain ◽

North China ◽

High Humidity ◽

The North ◽

The North China Plain ◽

Secondary Formation

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Simultaneous Measurements of Chemical Compositions of Fine Particles during Winter Haze Period in Urban Sites in China and Korea

Atmosphere ◽

10.3390/atmos11030292 ◽

2020 ◽

Vol 11 (3) ◽

pp. 292 ◽

Cited By ~ 2

Author(s):

Minhan Park ◽

Yujue Wang ◽

Jihyo Chong ◽

Haebum Lee ◽

Jiho Jang ◽

...

Keyword(s):

Biomass Burning ◽

Fine Particles ◽

Chemical Compositions ◽

Aerosol Formation ◽

Wind Speeds ◽

Simultaneous Measurements ◽

Dust Sources ◽

Secondary Formation ◽

Combustion Sources ◽

Burning Coal

We performed simultaneous measurements of chemical compositions of fine particles in Beijing, China and Gwangju, Korea to better understand their sources during winter haze period. We identified PM2.5 events in Beijing, possibly caused by a combination of multiple primary combustion sources (biomass burning, coal burning, and vehicle emissions) and secondary aerosol formation under stagnant conditions and/or dust sources under high wind speeds. During the PM2.5 events in Gwangju, the contribution of biomass burning and secondary formation of nitrate and organics to the fine particles content significantly increased under stagnant conditions. We commonly observed the increases of nitrogen-containing organic compounds and biomass burning inorganic (K+) and organic (levoglucosan) markers, suggesting the importance of biomass burning sources during the winter haze events (except dust event cases) at both sites. Pb isotope ratios indicated that the fraction of Pb originated from possibly industry and coal combustion sources increased during the PM2.5 events in Gwangju, relative to nonevent days.

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Primary emissions versus secondary formation of fine particulate matter in the most polluted city (Shijiazhuang) in North China

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-2283-2019 ◽

2019 ◽

Vol 19 (4) ◽

pp. 2283-2298 ◽

Cited By ~ 20

Author(s):

Ru-Jin Huang ◽

Yichen Wang ◽

Junji Cao ◽

Chunshui Lin ◽

Jing Duan ◽

...

Keyword(s):

Particulate Matter ◽

North China ◽

Fine Particulate Matter ◽

Mass Range ◽

Organic Aerosol ◽

Average Mass ◽

Episodic Events ◽

Secondary Formation ◽

Primary Emissions ◽

Pollution Events

Abstract. Particulate matter (PM) pollution is a severe environmental problem in the Beijing–Tianjin–Hebei (BTH) region in North China. PM studies have been conducted extensively in Beijing, but the chemical composition, sources, and atmospheric processes of PM are still relatively less known in nearby Tianjin and Hebei. In this study, fine PM in urban Shijiazhuang (the capital of Hebei Province) was characterized using an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM) from 11 January to 18 February in 2014. The average mass concentration of non-refractory submicron PM (diameter <1 µm, NR-PM1) was 178±101 µg m−3, and it was composed of 50 % organic aerosol (OA), 21 % sulfate, 12 % nitrate, 11 % ammonium, and 6 % chloride. Using the multilinear engine (ME-2) receptor model, five OA sources were identified and quantified, including hydrocarbon-like OA from vehicle emissions (HOA, 13 %), cooking OA (COA, 16 %), biomass burning OA (BBOA, 17 %), coal combustion OA (CCOA, 27 %), and oxygenated OA (OOA, 27 %). We found that secondary formation contributed substantially to PM in episodic events, whereas primary emissions were dominant (most significant) on average. The episodic events with the highest NR-PM1 mass range of 300–360 µg m−3 were comprised of 55 % of secondary species. On the contrary, a campaign-average low OOA fraction (27 %) in OA indicated the importance of primary emissions, and a low sulfur oxidation degree (FSO4) of 0.18 even at RH >90 % hinted at insufficient oxidation. These results suggested that in Shijiazhuang in wintertime fine PM was mostly from primary emissions without sufficient atmospheric aging, indicating opportunities for air quality improvement by mitigating direct emissions. In addition, secondary inorganic and organic (OOA) species dominated in pollution events with high-RH conditions, most likely due to enhanced aqueous-phase chemistry, whereas primary organic aerosol (POA) dominated in pollution events with low-RH and stagnant conditions. These results also highlighted the importance of meteorological conditions for PM pollution in this highly polluted city in North China.

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