Secondary aerosol formation in winter haze over the Beijing-Tianjin-Hebei Region, China

Highlights

• Characteristics and interannual variation of aerosol pollution are illustrated.

• Mechanisms of secondary aerosol formation in winter haze of North China are reviewed.

• Directions in future studies of secondary aerosol formation are provided.

Abstract

Severe haze pollution occurs frequently in the winter over the Beijing-Tianjin-Hebei (BTH) region (China), exerting profound impacts on air quality, visibility, and human health. The Chinese Government has taken strict mitigation actions since 2013 and has achieved a significant reduction in the annual mean PM_2.5 concentration over this region. However, the level of secondary aerosols during heavy haze episodes showed little decrease during this period. During heavy haze episodes, the concentrations of secondary aerosol components, including sulfate, nitrate and secondary organics, in aerosol particles increase sharply, acting as the main contributors to aerosol pollution. To achieve effective control of particle pollution in the BTH region, the precise and complete secondary aerosol formation mechanisms have been investigated, and advances have been made about the mechanisms of gas phase reaction, nucleation and heterogeneous reactions in forming secondary aerosols. This paper reviews the research progress in aerosol chemistry during haze pollution episodes in the BTH region, lays out the challenges in haze formation studies, and provides implications and directions for future research.

Graphical abstract

Keywords

Secondary aerosol formation / Regional haze / Photochemical reaction / Aqueous reaction / Chemical mechanism

References

[1] Bao F X, Li M, Zhang Y, Chen C C, Zhao J C (2018). Photochemical aging of Beijing urban PM_2.5: HONO production. Environmental Science & Technology, 52(11): 6309–6316

[2] Bei N F, Wu J R, Elser M, Feng T, Cao J J, El-Haddad I, Li X, Huang R J, Li Z Q, Long X, Xing L, Zhao S Y, Tie X X, Prevot A S H, Li G H (2017). Impacts of meteorological uncertainties on the haze formation in Beijing-Tianjin-Hebei (BTH) during wintertime: A case study. Atmospheric Chemistry and Physics, 17(23): 14579–14591

[3] Cai W J, Li K, Liao H, Wang H J, Wu L X (2017). Weather conditions conducive to Beijing severe haze more frequent under climate change. Nature Climate Change, 7(4): 257–262

[4] Cao C, Jiang W J, Wang B Y, Fang J H, Lang J D, Tian G, Jiang J K, Zhu T F (2014). Inhalable microorganisms in Beijing’s PM_2.5 and PM₁₀ pollutants during a severe smog event. Environmental Science & Technology, 48(3): 1499–1507

[5] Cao Z, Zhou X, Ma Y, Wang L, Wu R, Chen B, Wang W (2017). The concentrations, formations, relationships and modeling of sulfate, nitrate and ammonium (SNA) aerosols over China. Aerosol and Air Quality Research, 17(1): 84–97

[6] Chen D, Liu Z Q, Fast J, Ban J M (2016). Simulations of sulfate-nitrate-ammonium (SNA) aerosols during the extreme haze events over northern China in October 2014. Atmospheric Chemistry and Physics, 16(16): 10707–10724

[7] Chen R J, Zhao Z H, Kan H D (2013). Heavy smog and hospital visits in Beijing, China. American Journal of Respiratory and Critical Care Medicine, 188(9): 1170–1171

[8] Chen Y F, Zhou Y M, Zhao X Y (2020). PM_2.5 over North China based on MODIS AOD and effect of meteorological elements during 2003–2015. Frontiers of Environmental Science & Engineering, 14(2): 23

[9] Cheng J, Su J P, Cui T, Li X, Dong X, Sun F, Yang Y Y, Tong D, Zheng Y X, Li Y S, Li J X, Zhang Q, He K B (2019). Dominant role of emission reduction in PM_2.5 air quality improvement in Beijing during 2013–2017: A model-based decomposition analysis. Atmospheric Chemistry and Physics, 19(9): 6125–6146

[10] Cheng N L, Li Y T, Cheng B F, Wang X, Meng F, Wang Q, Qiu Q H (2018). Comparisons of two serious air pollution episodes in winter and summer in Beijing. Journal of Environmental Sciences- China, 69: 141–154

[11] Cheng Y, Engling G, He K B, Duan F K, Ma Y L, Du Z Y, Liu J M, Zheng M, Weber R J (2013). Biomass burning contribution to Beijing aerosol. Atmospheric Chemistry and Physics, 13(15): 7765–7781

[12] Cheng Y F, Zheng G J, Wei C, Mu Q, Zheng B, Wang Z B, Gao M, Zhang Q, He K B, Carmichael G, Poschl U, Su H (2016). Reactive nitrogen chemistry in aerosol water as a source of sulfate during haze events in China. Science Advances, 2(12): e1601530

[13] China Daily (2013). Clean air action plan to reduce pollution. China Society. Beijing: China Daily Information Co.

[14] Ehn M, Thornton J A, Kleist E, Sipilä M, Junninen H, Pullinen I, Springer M, Rubach F, Tillmann R, Lee B, Lopez-Hilfiker F, Andres S, Acir I H, Rissanen M, Jokinen T, Schobesberger S, Kangasluoma J, Kontkanen J, Nieminen T, Kurtén T, Nielsen L B, Jørgensen S, Kjaergaard H G, Canagaratna M, Maso M D, Berndt T, Petäjä T, Wahner A, Kerminen V M, Kulmala M, Worsnop D R, Wildt J, Mentel T F (2014). A large source of low-volatility secondary organic aerosol. Nature, 506(7489): 476–479

[15] Elser M, Huang R J, Wolf R, Slowik J G, Wang Q Y, Canonaco F, Li G H, Bozzetti C, Daellenbach K R, Huang Y, Zhang R J, Li Z Q, Cao J J, Baltensperger U, El-Haddad I, Prevot A S H (2016). New insights into PM_2.5 chemical composition and sources in two major cities in China during extreme haze events using aerosol mass spectrometry. Atmospheric Chemistry and Physics, 16(5): 3207–3225

[16] Gao J J, Wang K, Wang Y, Liu S H, Zhu C Y, Hao J M, Liu H J, Hua S B, Tian H Z (2018). Temporal-spatial characteristics and source apportionment of PM_2.5 as well as its associated chemical species in the Beijing-Tianjin-Hebei region of China. Environmental Pollution, 233: 714–724

[17] Gao M, Carmichael G R, Wang Y, Saide P E, Liu Z, Xin J, Shan Y, Wang Z (2017). Chemical and Meteorological Feedbacks in the Formation of Intense Haze Events. New York: Springer

[18] Ge B Z, Wang Z F, Lin W L, Xu X B, Li J, Ji D S, Ma Z Q (2018). Air pollution over the North China Plain and its implication of regional transport: A new sight from the observed evidences. Environmental Pollution, 234: 29–38

[19] Ge S S, Wang G H, Zhang S, Li D P, Xie Y N, Wu C, Yuan Q, Chen J M, Zhang H L (2019). Abundant NH₃ in China enhances atmospheric HONO production by promoting the heterogeneous reaction of SO₂ with NO₂. Environmental Science & Technology, 53(24): 14339–14347

[20] Guo S, Hu M, Peng J, Wu Z, Zamora M L, Shang D, Du Z, Zheng J, Fang X, Tang R, Wu Y, Zeng L, Shuai S, Zhang W, Wang Y, Ji Y, Li Y, Zhang A L, Wang W, Zhang F, Zhao J, Gong X, Wang C, Molina M J, Zhang R (2020). Remarkable nucleation and growth of ultrafine particles from vehicular exhaust. Proceedings of the National Academy of Sciences of the United States of America, 113(16): 4266–4271

[21] Guo S, Hu M, Zamora M L, Peng J, Shang D, Zheng J, Du Z, Wu Z, Shao M, Zeng L, Molina M J, Zhang R (2014). Elucidating severe urban haze formation in China. Proceedings of the National Academy of Sciences of the United States of America, 111(49): 17373–17378

[22] Han B, Zhang R, Yang W, Bai Z, Ma Z, Zhang W (2016a). Heavy haze episodes in Beijing during January 2013: Inorganic ion chemistry and source analysis using highly time-resolved measurements from an urban site. Science of the Total Environment, 544: 319–329

[23] Han X, Guo Q, Liu C, Fu P, Strauss H, Yang J, Hu J, Wei L, Ren H, Peters M, Wei R, Tian L (2016b). Using stable isotopes to trace sources and formation processes of sulfate aerosols from Beijing, China. Scientific Reports, 6(1): 29958

[24] Han X, Zhang M, Gao J, Wang S, Chai F (2014). Modeling analysis of the seasonal characteristics of haze formation in Beijing. Atmospheric Chemistry and Physics, 14(18): 10231–10248

[25] He P Z, Alexander B, Geng L, Chi X Y, Fan S D, Zhan H C, Kang H, Zheng G J, Cheng Y F, Su H, Liu C, Xie Z Q (2018a). Isotopic constraints on heterogeneous sulfate production in Beijing haze. Atmospheric Chemistry and Physics, 18(8): 5515–5528

[26] He P Z, Xie Z Q, Chi X Y, Yu X W, Fan S D, Kang H, Liu C, Zhan H C (2018b). Atmospheric Delta O-17(NO₃^‒) reveals nocturnal chemistry dominates nitrate production in Beijing haze. Atmospheric Chemistry and Physics, 18(19): 14465–14476

[27] Hong C P, Zhang Q, Zhang Y, Davis S J, Tong D, Zheng Y X, Liu Z, Guan D B, He K B, Schellnhuber H J (2019). Impacts of climate change on future air quality and human health in China. Proceedings of the National Academy of Sciences of the United States of America, 116(35): 17193–17200

[28] Hu W, Hu M, Hu W, Jimenez J L, Yuan B, Chen W, Wang M, Wu Y, Chen C, Wang Z, Peng J, Zeng L, Shao M (2016). Chemical composition, sources, and aging process of submicron aerosols in Beijing: Contrast between summer and winter. Journal of Geophysical Research, D, Atmospheres, 121(4): 1955–1977

[29] Hu W, Hu M, Hu W W, Zheng J, Chen C, Wu Y, Guo S (2017). Seasonal variations in high time-resolved chemical compositions, sources, and evolution of atmospheric submicron aerosols in the megacity Beijing. Atmospheric Chemistry and Physics, 17(16): 9979–10000

[30] Jayaratne R, Pushpawela B, He C, Li H, Gao J, Chai F, Morawska L (2017). Observations of particles at their formation sizes in Beijing, China. Atmospheric Chemistry and Physics, 17(14): 8825–8835

[31] Kuang C, Mcmurry P H, Mccormick A V, Eisele F L (2008). Dependence of nucleation rates on sulfuric acid vapor concentration in diverse atmospheric locations. Journal of Geophysical Research, 113(D10): D10209

[32] Kulmala M (2003). How particles nucleate and grow. Science, 302(5647): 1000–1001

[33] Kulmala M (2015). China’s choking cocktail. Nature, 526(7574): 497–499

[34] Kulmala M (2018). Build a global Earth observatory. Nature, 553(7686): 21–23

[35] Kulmala M, Kontkanen J, Junninen H, Lehtipalo K, Manninen H E, Nieminen T, Petäjä T, Sipilä M, Schobesberger S, Rantala P, Franchin A, Jokinen T, Järvinen E, Äijälä M, Kangasluoma J, Hakala J, Aalto P P, Paasonen P, Mikkilä J, Vanhanen J, Aalto J, Hakola H, Makkonen U, Ruuskanen T, Mauldin R L, Duplissy J, Vehkamäki H, Bäck J, Kortelainen A, Riipinen I, Kurtén T, Johnston M V, Smith J N, Ehn M, Mentel T F, Lehtinen K E J, Laaksonen A, Kerminen V M, Worsnop D R (2013). Direct observations of atmospheric aerosol nucleation. Science, 339(6122): 943–946

[36] Li G H, Bei N F, Cao J J, Huang R J, Wu J R, Feng T, Wang Y C, Liu S X, Zhang Q, Tie X X, Molina L T (2017a). A possible pathway for rapid growth of sulfate during haze days in China. Atmospheric Chemistry and Physics, 17(5): 3301–3316

[37] Li X, Jiang L, Bai Y, Yang Y, Liu S, Chen X, Xu J, Liu Y, Wang Y, Guo X, Wang Y, Wang G (2019a). Wintertime aerosol chemistry in Beijing during haze period: Significant contribution from secondary formation and biomass burning emission. Atmospheric Research, 218: 25–33

[38] Li X, Wu J R, Elser M, Feng T, Cao J J, El-Haddad I, Huang R J, Tie X X, Prevot A S H, Li G H (2018). Contributions of residential coal combustion to the air quality in Beijing-Tianjin-Hebei (BTH), China: a case study. Atmospheric Chemistry and Physics, 18(14): 10675–10691

[39] Li X X, Song S J, Zhou W, Hao J M, Worsnop D R, Jiang J K (2019b). Interactions between aerosol organic components and liquid water content during haze episodes in Beijing. Atmospheric Chemistry and Physics, 19(19): 12163–12174

[40] Li Y J, Sun Y, Zhang Q, Li X, Li M, Zhou Z, Chan C K (2017b). Real-time chemical characterization of atmospheric particulate matter in China: A review. Atmospheric Environment, 158: 270–304

[41] Liu C, Dai H C, Zhang L, Feng C C (2019a). The impacts of economic restructuring and technology upgrade on air quality and human health in Beijing-Tianjin-Hebei region in China. Frontiers of Environmental Science & Engineering, 13(5): 70

[42] Liu J M, Wang P F, Zhang H L, Du Z Y, Zheng B, Yu Q Q, Zheng G J, Ma Y L, Zheng M, Cheng Y, Zhang Q, He K B (2020). Integration of field observation and air quality modeling to characterize Beijing aerosol in different seasons. Chemosphere, 242: 125195

[43] Liu L, Wu J R, Liu S X, Li X, Zhou J M, Feng T, Qian Y, Cao J J, Tie X X, Li G H (2019b). Effects of organic coating on the nitrate formation by suppressing the N₂O₅ heterogeneous hydrolysis: A case study during wintertime in Beijing-Tianjin-Hebei (BTH). Atmospheric Chemistry and Physics, 19(12): 8189–8207

[44] Liu M, Huang X, Song Y, Tang J, Cao J, Zhang X, Zhang Q, Wang S, Xu T, Kang L, Cai X, Zhang H, Yang F, Wang H, Yu J Z, Lau A K H, He L, Huang X, Duan L, Ding A, Xue L, Gao J, Liu B, Zhu T (2019c). Ammonia emission control in China would mitigate haze pollution and nitrogen deposition, but worsen acid rain. Proceedings of the National Academy of Sciences, 116(16): 7760–7765

[45] Liu X G, Li J, Qu Y, Han T, Hou L, Gu J, Chen C, Yang Y, Liu X, Yang T, Zhang Y, Tian H, Hu M (2013). Formation and evolution mechanism of regional haze: a case study in the megacity Beijing, China. Atmospheric Chemistry and Physics, 13(9): 4501–4514

[46] Liu X G, Sun K, Qu Y, Hu M, Sun Y L, Zhang F, Zhang Y H (2015). Secondary formation of sulfate and nitrate during a haze episode in megacity Beijing, China. Aerosol and Air Quality Research, 15(6): 2246–2257

[47] Liu Y, Zheng M, Yu M Y, Cai X H, Du H Y, Li J, Zhou T, Yan C Q, Wang X S, Shi Z B, Harrison R M, Zhang Q, He K B (2019d). High-time-resolution source apportionment of PM_2.5 in Beijing with multiple models. Atmospheric Chemistry and Physics, 19(9): 6595–6609

[48] Liu Y C, Wu Z J, Wang Y, Xiao Y, Gu F T, Zheng J, Tan T Y, Shang D J, Wu Y S, Zeng L M, Hu M, Bateman A P, Martin S T (2017). Submicrometer particles are in the liquid state during heavy haze episodes in the urban atmosphere of Beijing, China. Environmental Science & Technology Letters, 4(10): 427–432

[49] Lu K, Guo S, Tan Z, Wang H, Shang D, Liu Y, Li X, Wu Z, Hu M, Zhang Y (2018). Exploring atmospheric free-radical chemistry in China: The self-cleansing capacity and the formation of secondary air pollution. National Science Review, 6(3): 579–594

[50] Lu K D, Fuchs H, Hofzumahaus A, Tan Z F, Wang H C, Zhang L, Schmitt S H, Rohrer F, Bohn B, Broch S, Dong H B, Gkatzelis G I, Hohaus T, Holland F, Li X, Liu Y, Liu Y H, Ma X F, Novelli A, Schlag P, Shao M, Wu Y S, Wu Z J, Zeng L M, Hu M, Kiendler-Scharr A, Wahner A, Zhang Y H (2019). Fast photochemistry in wintertime haze: Consequences for pollution mitigation strategies. Environmental Science & Technology, 53(18): 10676–10684

[51] Lv B, Zhang B, Bai Y (2016). A systematic analysis of PM_2.5 in Beijing and its sources from 2000 to 2012. Atmospheric Environment, 124: 98–108

[52] Ma J, Xu X, Zhao C, Yan P (2012). A review of atmospheric chemistry research in China: Photochemical smog, haze pollution, and gas-aerosol interactions. Advances in Atmospheric Sciences, 29(5): 1006–1026

[53] Ma Q X, Wu Y F, Zhang D Z, Wang X J, Xia Y J, Liu X Y, Tian P, Han Z W, Xia X G, Wang Y, Zhang R J (2017). Roles of regional transport and heterogeneous reactions in the PM_2.5 increase during winter haze episodes in Beijing. Science of the Total Environment, 599: 246–253

[54] Ma X F, Tan Z F, Lu K D, Yang X P, Liu Y H, Li S L, Li X, Chen S Y, Novelli A, Cho C M, Zeng L M, Wahner A, Zhang Y H (2019). Winter photochemistry in Beijing: Observation and model simulation of OH and HO₂ radicals at an urban site. Science of the Total Environment, 685: 85–95

[55] Moch J M, Dovrou E, Mickley L J, Keutsch F N, Cheng Y, Jacob D J, Jiang J K, Li M, Munger J W, Qiao X H, Zhang Q (2018). Contribution of hydroxymethane sulfonate to ambient particulate matter: A potential explanation for high particulate sulfur during severe winter haze in Beijing. Geophysical Research Letters, 45(21): 11969–11979

[56] Mutzel A, Poulain L, Berndt T, Iinuma Y, Rodigast M, Boge O, Richters S, Spindler G, Sipila M, Jokinen T, Kulmala M, Herrmann H (2015). Highly oxidized multifunctional organic compounds observed in tropospheric particles: A field and laboratory study. Environmental Science & Technology, 49(13): 7754–7761

[57] Peng J, Hu M, Guo S, Du Z, Zheng J, Shang D, Zamora M L, Zeng L, Shao M, Wu Y S, Zheng J, Wang Y, Glen C R, Collins D R, Molina M J, Zhang R (2016). Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments. Proceedings of the National Academy of Sciences of the United States of America, 113(16): 4266–4271

[58] Pöschl U (2005). Atmospheric aerosols: Composition, transformation, climate and health effects. Angewandte Chemie International Edition, 44(46): 7520–7540

[59] Qi J, Zheng B, Li M, Yu F, Chen C, Liu F, Zhou X, Yuan J, Zhang Q, He K (2017). A high-resolution air pollutants emission inventory in 2013 for the Beijing-Tianjin-Hebei region, China. Atmospheric Environment, 170(Suppl C): 156–168

[60] Qi X, Ding A, Roldin P, Xu Z, Zhou P, Sarnela N, Nie W, Huang X, Rusanen A, Ehn M, Rissanen M P, Petäjä T, Kulmala M, Boy M (2018). Modelling studies of HOMs and their contributions to new particle formation and growth: comparison of boreal forest in Finland and a polluted environment in China. Atmospheric Chemistry and Physics, 18(16): 11779–11791

[61] Qin M R, Chen Z M, Shen H Q, Li H, Wu H H, Wang Y (2018). Impacts of heterogeneous reactions to atmospheric peroxides: Observations and budget analysis study. Atmospheric Environment, 183: 144–153

[62] Qu Y, Chen Y, Liu X G, Zhang J W, Guo Y T, An J L (2019). Seasonal effects of additional HONO sources and the heterogeneous reactions of N₂O₅ on nitrate in the North China Plain. Science of the Total Environment, 690: 97–107

[63] Riccobono F, Schobesberger S, Scott C E, Dommen J, Ortega I K, Rondo L, Almeida J, Amorim A, Bianchi F, Breitenlechner M, David A, Downard A, Dunne E M, Duplissy J, Ehrhart S, Flagan R C, Franchin A, Hansel A, Junninen H, Kajos M, Keskinen H, Kupc A, Kürten A, Kvashin A N, Laaksonen A, Lehtipalo K, Makhmutov V, Mathot S, Nieminen T, Onnela A, Petäjä T, Praplan A P, Santos F D, Schallhart S, Seinfeld J H, Sipilä M, Spracklen D V, Stozhkov Y, Stratmann F, Tomé A, Tsagkogeorgas G, Vaattovaara P, Viisanen Y, Vrtala A, Wagner P E, Weingartner E, Wex H, Wimmer D, Carslaw K S, Curtius J, Donahue N M, Kirkby J, Kulmala M, Worsnop D R, Baltensperger U (2014). Oxidation products of biogenic emissions contribute to nucleation of atmospheric particles. Science, 344(6185): 717–721

[64] Shao J, Chen Q, Wang Y, Lu X, He P, Sun Y, Shah V, Martin R V, Philip S, Song S, Zhao Y, Xie Z, Zhang L, Alexander B (2019). Heterogeneous sulfate aerosol formation mechanisms during wintertime Chinese haze events: Air quality model assessment using observations of sulfate oxygen isotopes in Beijing. Atmospheric Chemistry and Physics, 19(9): 6107–6123

[65] Shen L, Jacob D J, Mickley L J, Wang Y X, Zhang Q (2018). Insignificant effect of climate change on winter haze pollution in Beijing. Atmospheric Chemistry and Physics, 18(23): 17489–17496

[66] Sipilä M, Berndt T, Petäjä T, Brus D, Vanhanen J, Stratmann F, Patokoski J, Mauldin R L, Hyvärinen A P, Lihavainen H, Kulmala M (2010). The role of sulfuric acid in atmospheric nucleation. Science, 327(5970): 1243–1246

[67] Song S J, Gao M, Xu W Q, Shao J Y, Shi G L, Wang S X, Wang Y X, Sun Y L, Mcelroy M B (2018). Fine-particle pH for Beijing winter haze as inferred from different thermodynamic equilibrium models. Atmospheric Chemistry and Physics, 18(10): 7423–7438

[68] Song S J, Gao M, Xu W Q, Sun Y L, Worsnop D R, Jayne J T, Zhang Y Z, Zhu L, Li M, Zhou Z, Cheng C L, Lv Y B, Wang Y, Peng W, Xu X B, Lin N, Wang Y X, Wang S X, Munger J W, Jacob D J, Mcelroy M B (2019). Possible heterogeneous chemistry of hydroxymethanesulfonate (HMS) in northern China winter haze. Atmospheric Chemistry and Physics, 19(2): 1357–1371

[69] Su X, Tie X, Li G, Cao J, Huang R, Feng T, Long X, Xu R (2017). Effect of hydrolysis of N₂O₅ on nitrate and ammonium formation in Beijing China: WRF-Chem model simulation. Science of the Total Environment, 579: 221–229

[70] Sun Y L, Chen C, Zhang Y J, Xu W Q, Zhou L B, Cheng X L, Zheng H T, Ji D S, Li J, Tang X, Fu P Q, Wang Z F (2016a). Rapid formation and evolution of an extreme haze episode in Northern China during winter 2015. Scientific Reports, 6(1): 27151

[71] Sun Y L, Du W, Fu P Q, Wang Q Q, Li J, Ge X L, Zhang Q, Zhu C M, Ren L J, Xu W Q, Zhao J, Han T T, Worsnop D R, Wang Z F (2016b). Primary and secondary aerosols in Beijing in winter: Sources, variations and processes. Atmospheric Chemistry and Physics, 16(13): 8309–8329

[72] Sun Y L, Jiang Q, Wang Z F, Fu P Q, Li J, Yang T, Yin Y (2014). Investigation of the sources and evolution processes of severe haze pollution in Beijing in January 2013. Journal of Geophysical Research, D, Atmospheres, 119(7): 4380–4398

[73] Sun Y L, Wang Z F, Fu P Q, Jiang Q, Yang T, Li J, Ge X L (2013a). The impact of relative humidity on aerosol composition and evolution processes during wintertime in Beijing, China. Atmospheric Environment, 77: 927–934

[74] Sun Y L, Wang Z F, Fu P Q, Yang T, Jiang Q, Dong H B, Li J, Jia J J (2013b). Aerosol composition, sources and processes during wintertime in Beijing, China. Atmospheric Chemistry and Physics, 13(9): 4577–4592

[75] Tan J H, Duan J C, Zhen N J, He K B, Hao J M (2016). Chemical characteristics and source of size-fractionated atmospheric particle in haze episode in Beijing. Atmospheric Research, 167: 24–33

[76] Tan T, Hu M, Li M, Guo Q, Wu Y, Fang X, Gu F, Wang Y, Wu Z (2018). New insight into PM_2.5 pollution patterns in Beijing based on one-year measurement of chemical compositions. Science of the Total Environment, 621: 734–743

[77] Tang X, Zhang X S, Ci Z J, Guo J, Wang J Q (2016). Speciation of the major inorganic salts in atmospheric aerosols of Beijing, China: Measurements and comparison with model. Atmospheric Environment, 133: 123–134

[78] Tie X, Huang R J, Cao J, Zhang Q, Cheng Y, Su H, Chang D, Pöschl U, Hoffmann T, Dusek U, Li G, Worsnop D R, O’dowd C D (2017). Severe pollution in China amplified by atmospheric moisture. Scientific Reports, 7(1): 15760

[79] Vu T V, Shi Z B, Cheng J, Zhang Q, He K B, Waneg S X, Harrison R M (2019). Assessing the impact of clean air action on air quality trends in Beijing using a machine learning technique. Atmospheric Chemistry and Physics, 19(17): 11303–11314

[80] Wang G H, Zhang R Y, Gomez M E, Yang L X, Zamora M L, Hu M, Lin Y, Peng J F, Guo S, Meng J J, Li J J, Cheng C L, Hu T F, Ren Y Q, Wang Y S, Gao J, Cao J J, An Z S, Zhou W J, Li G H, Wang J Y, Tian P F, Marrero-Ortiz W, Secrest J, Du Z F, Zheng J, Shang D J, Zeng L M, Shao M, Wang W G, Huang Y, Wang Y, Zhu Y J, Li Y X, Hu J X, Pan B, Cai L, Cheng Y T, Ji Y M, Zhang F, Rosenfeld D, Liss P S, Duce R A, Kolb C E, Molina M J (2016). Persistent sulfate formation from London Fog to Chinese haze. Proceedings of the National Academy of Sciences of the United States of America, 113(48): 13630–13635

[81] Wang H C, Lu K D, Chen X R, Zhu Q D, Wu Z J, Wu Y S, Sun K (2018). Fast particulate nitrate formation via N₂O₅ uptake aloft in winter in Beijing. Atmospheric Chemistry and Physics, 18(14): 10483–10495

[82] Wang L T, Wei Z, Yang J, Zhang Y, Zhang F F, Su J, Meng C C, Zhang Q (2014a). The 2013 severe haze over southern Hebei, China: model evaluation, source apportionment, and policy implications. Atmospheric Chemistry and Physics, 14(6): 3151–3173

[83] Wang Q, Shao M, Zhang Y, Wei Y, Hu M, Guo S (2009). Source apportionment of fine organic aerosols in Beijing. Atmospheric Chemistry and Physics, 9(21): 8573–8585

[84] Wang Y H, Wang Y S, Wang L L, Petaja T, Zha Q Z, Gong C S, Li S X, Pan Y P, Hu B, Xin J Y, Kulmala M (2019). Increased inorganic aerosol fraction contributes to air pollution and haze in China. Atmospheric Chemistry and Physics, 19(9): 5881–5888

[85] Wang Y H, Yu M, Wang Y S, Tang G Q, Song T, Zhou P T, Liu Z R, Hu B, Ji D S, Wang L L, Zhu X W, Yan C, Ehn M, Gao W K, Pan Y P, Xin J Y, Sun Y, Kerminen V M, Kulmala M, Petaja T (2020). Rapid formation of intense haze episodes via aerosol-boundary layer feedback in Beijing. Atmospheric Chemistry and Physics, 20(1): 45–53

[86] Wang Y S, Yao L, Wang L L, Liu Z R, Ji D S, Tang G Q, Zhang J K, Sun Y, Hu B, Xin J Y (2014b). Mechanism for the formation of the January 2013 heavy haze pollution episode over central and eastern China. Science China. Earth Sciences, 57(1): 14–25

[87] Wang Y X, Zhang Q Q, Jiang J K, Zhou W, Wang B Y, He K B, Duan F K, Zhang Q, Philip S, Xie Y Y (2014c). Enhanced sulfate formation during China’s severe winter haze episode in January 2013 missing from current models. Journal of Geophysical Research, D, Atmospheres, 119(17): 10425–10440

[88] Wang Z, Wang Z, Li J, Zheng H, Yan P, Li J (2014d). Development of a meteorology-chemistry two-way coupled numerical model (WRF-NAQPMS) and its application in a severe autumn haze simulation over the Beijing-Tianjin-Hebei Area, China. Climatic and Environmental Research, 19(2): 153–163

[89] Wang Z, Wu Z, Yue D, Shang D, Guo S, Sun J, Ding A, Wang L, Jiang J, Guo H, Gao J, Cheung H C, Morawska L, Keywood M, Hu M (2017). New particle formation in China: Current knowledge and further directions. Science of the Total Environment, 577: 258–266

[90] Wang Z B, Hu M, Yue D L, Zheng J, Zhang R Y, Wiedensohler A, Wu Z J, Nieminen T, Boy M (2011). Evaluation on the role of sulfuric acid in the mechanisms of new particle formation for Beijing case. Atmospheric Chemistry and Physics, 11(24): 12663–12671

[91] Wen L, Xue L K, Wang X F, Xu C H, Chen T S, Yang L X, Wang T, Zhang Q Z, Wang W X (2018). Summertime fine particulate nitrate pollution in the North China Plain: increasing trends, formation mechanisms and implications for control policy. Atmospheric Chemistry and Physics, 18(15): 11261–11275

[92] Xiao S, Wang M Y, Yao L, Kulmala M, Zhou B, Yang X, Chen J M, Wang D F, Fu Q Y, Worsnop D R, Wang L (2015). Strong atmospheric new particle formation in winter in urban Shanghai, China. Atmospheric Chemistry and Physics, 15(4): 1769–1781

[93] Xie Y J (2020).Yearly changes of the sulfate-nitrate-ammonium aerosols and the relationship with their precursors from 1999 to 2016 in Beijing. Environmental Science And Pollution Research, 27(8): 8350–8358

[94] Xing L, Wu J R, Elser M, Tong S R, Liu S X, Li X, Liu L, Cao J J, Zhou J M, El-Haddad I, Huang R J, Ge M F, Tie X X, Prevot A S H, Li G H (2019). Wintertime secondary organic aerosol formation in Beijing-Tianjin-Hebei (BTH): contributions of HONO sources and heterogeneous reactions. Atmospheric Chemistry and Physics, 19(4): 2343–2359

[95] Xu Q C, Wang S X, Jiang J K, Bhattarai N, Li X X, Chang X, Qiu X H, Zheng M, Hua Y, Hao J M (2019a). Nitrate dominates the chemical composition of PM_2.5 during haze event in Beijing, China. Science of the Total Environment, 689: 1293–1303

[96] Xu W Q, Han T T, Du W, Wang Q Q, Chen C, Zhao J, Zhang Y J, Li J, Fu P Q, Wang Z F, Worsnop D R, Sun Y L (2017). Effects of aqueous-phase and photochemical processing on secondary organic aerosol formation and evolution in Beijing, China. Environmental Science & Technology, 51(2): 762–770

[97] Xu W Q, Sun Y L, Wang Q Q, Zhao J, Wang J F, Ge X L, Xie C H, Zhou W, Du W, Li J, Fu P Q, Wang Z F, Worsnop D R, Coe H (2019b). Changes in aerosol chemistry from 2014 to 2016 in winter in Beijing: insights from high-resolution aerosol mass spectrometry. Journal of Geophysical Research, D, Atmospheres, 124(2): 1132–1147

[98] Xu X, Wang Y, Zhao T, Cheng X, Meng Y, Ding G (2015). Harbor effect of large topography on haze distribution in eastern China and its climate modulation on decadal variations in haze. Chinese Science Bulletin, 60(12): 1132–1143

[99] Xu Y L, Xue W B, Lei Y, Zhao Y, Cheng S Y, Ren Z H, Huang Q (2018). Impact of meteorological conditions on PM_2.5 pollution in China during winter. Atmosphere, 9(11): 429

[100] Xue J, Yuan Z, Griffith S M, Yu X, Lau A K H, Yu J Z (2016). Sulfate formation enhanced by a cocktail of high NO_x, SO₂, particulate matter, and droplet pH during haze-fog events in megacities in China: An observation-based modeling investigation. Environmental Science & Technology, 50(14): 7325–7334

[101] Yang Y R, Liu X G, Qu Y, An J L, Jiang R, Zhang Y H, Sun Y L, Wu Z J, Zhang F, Xu W Q, Ma Q X (2015). Characteristics and formation mechanism of continuous hazes in China: A case study during the autumn of 2014 in the North China Plain. Atmospheric Chemistry and Physics, 15(14): 8165–8178

[102] Yao L, Garmash O, Bianchi F, Zheng J, Yan C, Kontkanen J, Junninen H, Mazon S B, Ehn M, Paasonen P, Sipila M, Wang M Y, Wang X K, Xiao S, Chen H F, Lu Y Q, Zhang B W, Wang D F, Fu Q Y, Geng F H, Li L, Wang H L, Qiao L P, Yang X, Chen J M, Kerminen V M, Petaja T, Worsnop D R, Kulmala M, Wang L (2018). Atmospheric new particle formation from sulfuric acid and amines in a Chinese megacity. Science, 361(6399): 278–281

[103] Yao L, Yang L X, Yuan Q, Yan C, Dong C, Meng C P, Sui X, Yang F, Lu Y L, Wang W X (2016). Sources apportionment of PM_2.5 in a background site in the North China Plain. Science of the Total Environment, 541: 590–598

[104] Ye C, Liu P F, Ma Z B, Xue C Y, Zhang C L, Zhang Y Y, Liu J F, Liu C T, Sun X, Mu Y J (2018). High H₂O₂ concentrations observed during haze periods during the winter in Beijing: importance of H₂O₂ oxidation in sulfate formation. Environmental Science & Technology Letters, 5(12): 757–763

[105] Zamora M L, Peng J F, Hu M, Guo S, Marrero-Ortiz W, Shang D J, Zheng J, Du Z F, Wu Z J, Zhang R Y (2019). Wintertime aerosol properties in Beijing. Atmospheric Chemistry and Physics, 19(22): 14329–14338

[106] Zhai S X, An X Q, Zhao T L, Sun Z B, Wang W, Hou Q, Guo Z Y, Wang C (2018). Detection of critical PM_2.5 emission sources and their contributions to a heavy haze episode in Beijing, China, using an adjoint model. Atmospheric Chemistry and Physics, 18(9): 6241–6258

[107] Zhai S X, Jacob D J, Wang X, Shen L, Li K, Zhang Y Z, Gui K, Zhao T L, Liao H (2019). Fine particulate matter (PM_2.5) trends in China, 2013–2018: Separating contributions from anthropogenic emissions and meteorology. Atmospheric Chemistry and Physics, 19(16): 11031–11041

[108] Zhang F, Wang Y, Peng J, Chen L, Sun Y, Duan L, Ge X, Li Y, Zhao J, Liu C, Zhang X, Zhang G, Pan Y, Wang Y, Zhang A L, Ji Y, Wang G, Hu M, Molina M J, Zhang R (2020). An unexpected catalyst dominates formation and radiative forcing of regional haze. Proceedings of the National Academy of Sciences of the United States of America, 117(8): 3960–3966

[109] Zhang H Y, Cheng S Y, Yao S, Wang X Q, Wang C D (2019a). Insights into the temporal and spatial characteristics of PM_2.5 transport flux across the district, city and region in the North China Plain. Atmospheric Environment, 218: 117010

[110] Zhang J K, Sun Y, Liu Z R, Ji D S, Hu B, Liu Q, Wang Y S (2014). Characterization of submicron aerosols during a month of serious pollution in Beijing, 2013. Atmospheric Chemistry and Physics, 14(6): 2887–2903

[111] Zhang J W, Chen J M, Xue C Y, Chen H, Zhang Q, Liu X G, Mu Y J, Guo Y T, Wang D Y, Chen Y, Li J L, Qu Y, An J L (2019b). Impacts of six potential HONO sources on HO_x budgets and SOA formation during a wintertime heavy haze period in the North China Plain. Science of the Total Environment, 681: 110–123

[112] Zhang Q, Zheng Y X, Tong D, Shao M, Wang S X, Zhang Y H, Xu X D, Wang J N, He H, Liu W Q, Ding Y H, Lei Y, Li J H, Wang Z F, Zhang X Y, Wang Y S, Cheng J, Liu Y, Shi Q R, Yan L, Geng G N, Hong C P, Li M, Liu F, Zheng B, Cao J J, Ding A J, Gao J, Fu Q Y, Huo J T, Liu B X, Liu Z R, Yang F M, He K B, Hao J M (2019c). Drivers of improved PM_2.5 air quality in China from 2013 to 2017. Proceedings of the National Academy of Sciences of the United States of America, 116(49): 24463–24469

[113] Zhang Q Q, Ma Q, Zhao B, Liu X Y, Wang Y X, Jia B X, Zhang X Y (2018). Winter haze over North China Plain from 2009 to 2016: Influence of emission and meteorology. Environmental Pollution, 242: 1308–1318

[114] Zhang R, Suh I, Zhao J, Zhang D, Fortner E C, Tie X, Molina L T, Molina M J (2004). Atmospheric new particle formation enhanced by organic acids. Science, 304(5676): 1487–1490

[115] Zhang R, Wang G, Guo S, Zamora M L, Ying Q, Lin Y, Wang W, Hu M, Wang Y (2015a). Formation of urban fine particulate matter. Chemical Reviews, 115(10): 3803–3855

[116] Zhang X Y, Wang J Z, Wang Y Q, Liu H L, Sun J Y, Zhang Y M (2015b). Changes in chemical components of aerosol particles in different haze regions in China from 2006 to 2013 and contribution of meteorological factors the. Atmospheric Chemistry and Physics, 15(22): 12935–12952

[117] Zhang Y, Huang W, Cai T Q, Fang D Q, Wang Y Q, Song J, Hu M, Zhang Y X (2016). Concentrations and chemical compositions of fine particles (PM_2.5) during haze and non-haze days in Beijing. Atmospheric Research, 174: 62–69

[118] Zhao B, Wu W J, Wang S X, Xing J, Chang X, Liou K N, Jiang J H, Gu Y, Jang C, Fu J S, Zhu Y, Wang J D, Lin Y, Hao J M (2017). A modeling study of the nonlinear response of fine particles to air pollutant emissions in the Beijing-Tianjin-Hebei region. Atmospheric Chemistry and Physics, 17(19): 12031–12050

[119] Zhao D D, Xin J Y, Gong C S, Quan J N, Liu G J, Zhao W P, Wang Y S, Liu Z, Song T (2019). The formation mechanism of air pollution episodes in Beijing city: Insights into the measured feedback between aerosol radiative forcing and the atmospheric boundary layer stability. Science of the Total Environment, 692: 371–381

[120] Zhao X J, Zhao P S, Xu J, Meng W, Pu W W, Dong F, He D, Shi Q F (2013). Analysis of a winter regional haze event and its formation mechanism in the North China Plain. Atmospheric Chemistry and Physics, 13(11): 5685–5696

[121] Zheng B, Tong D, Li M, Liu F, Hong C P, Geng G N, Li H Y, Li X, Peng L Q, Qi J, Yan L, Zhang Y X, Zhao H Y, Zheng Y X, He K B, Zhang Q (2018). Trends in China’s anthropogenic emissions since 2010 as the consequence of clean air actions. Atmospheric Chemistry and Physics, 18(19): 14095–14111

[122] Zheng G J, Duan F K, Ma Y L, Zhang Q, Huang T, Kimoto T, Cheng Y F, Su H, He K B (2016). Episode-based evolution pattern analysis of haze pollution: Method development and results from Beijing, China. Environmental Science & Technology, 50(9): 4632–4641

[123] Zheng G J, Duan F K, Su H, Ma Y L, Cheng Y, Zheng B, Zhang Q, Huang T, Kimoto T, Chang D, Pöschl U, Cheng Y F, He K B (2015). Exploring the severe winter haze in Beijing: The impact of synoptic weather, regional transport and heterogeneous reactions. Atmospheric Chemistry and Physics, 15(6): 2969–2983

[124] Zhong W G, Yin Z C, Wang H J (2019). The relationship between anticyclonic anomalies in northeastern Asia and severe haze in the Beijing-Tianjin-Hebei region. Atmospheric Chemistry and Physics, 19(9): 5941–5957

[125] Zhu T, Shang J, Zhao D F (2011). The roles of heterogeneous chemical processes in the formation of an air pollution complex and gray haze. Science China. Chemistry, 54(1): 145–153

[126] Zollner J H, Glasoe W A, Panta B, Carlson K K, Mcmurry P H, Hanson D R (2012). Sulfuric acid nucleation: Power dependencies, variation with relative humidity, and effect of bases. Atmospheric Chemistry and Physics, 12(10): 4399–4411

Acknowledgements

This research has been supported by the National Natural Science Foundation of China (Grant Nos. 91844301 and 91544214), National Research Program for Key Issues in Air Pollution Control (DQGG0103), National Key Research and Development Program of China (No. 2016YFC0202000: Task 3). The authors want to thank Dr. Shaomeng Li for the language polishing, Nan Xu for data analysis support and Tianyi Tan for figure beautification. Xiangxinyue Meng provided the photos in the graphic abstract.

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