The Synergistic Role of Sulfuric Acid, Bases, and Oxidized Organics Governing New‐Particle Formation in Beijing

Chao Yan,Xiaoxiao Li,Meredith Schervish,Yiqun Lu,Jingkun Jiang,Matthew Bloss,Mo Xue,Hui Li,Neil M Donahue,Biwu Chu,Lubna Dada,Maofa Ge,Xuemeng Chen,Qingxin Ma,Markku Kulmala,Shixian Wang,Yiliang Liu,Juha Kangasluoma,Anton Rusanen,Hong He,Jun Zheng,Dongsen Yang,Tuija Jokinen,Benjamin Foreback,Ying Zhou,Mona Kurppa,Lei Yao,Yan Ma,Liine Heikkinen,Haiyan Li,Qi Chen,Tom Kokkonen,Pauli Simonen,Veli‐Matti Kerminen Veli‐Matti Kerminen,Wei Nie,Lin Wang,Yongchun Liu,Katrianne Lehtipalo,Runlong Cai,Federico Bianchi,Pekka Rantala,Douglas R Worsnop,Yonghong Wang,Rujing Yin,Tianzeng Chen,Pauli Paasonen,Jiaxin Ruan,Rosaria E Pileci,Tommy Chan,Heikki Junninen,Weigang Wang,Nina Sarnela,Rima Baalbaki,Joni Kujansuu,Jenni Kontkanen,Chuanwei Yan ,Yuan Fu ,Guofu Yang ,Kaspar R Daellenbach ,Olga Garmаsh ,Chao Deng ,Xu‐Cheng He ,Tuukka Petäj̈ä

doi:10.1029/2020gl091944

Abstract

AbstractIntense and frequent new particle formation (NPF) events have been observed in polluted urban environments, yet the dominant mechanisms are still under debate. To understand the key species and governing processes of NPF in polluted urban environments, we conducted comprehensive measurements in downtown Beijing during January–March, 2018. We performed detailed analyses on sulfuric acid cluster composition and budget, as well as the chemical and physical properties of oxidized organic molecules (OOMs). Our results demonstrate that the fast clustering of sulfuric acid (H2SO4) and base molecules triggered the NPF events, and OOMs further helped grow the newly formed particles toward climate‐ and health‐relevant sizes. This synergistic role of H2SO4, base species, and OOMs in NPF is likely representative of polluted urban environments where abundant H2SO4 and base species usually co‐exist, and OOMs are with moderately low volatility when produced under high NOx concentrations.

Highlights

Atmospheric aerosol particles substantially affect climate and human health (Heal et al, 2012)
The reduced new particle formation (NPF) frequency in March is clearly associated with high condensation sink (CS), which is usually encountered when air masses come from polluted areas located on the south and east of Beijing
With state-of-the-art instruments, we track the particle evolution from molecules to clusters and to particles. Based on such comprehensive measurements, we depict a complete picture of NPF in wintertime Beijing, including both the initial clustering and the subsequent cluster growth driven by different vapors

Summary

Introduction

Atmospheric aerosol particles substantially affect climate and human health (Heal et al, 2012). Previous studies have suggested that high aerosol surface concentration is one primary parameter that governs the occurrence of NPF in polluted environments (Cai, Yang, et al, 2017; Deng et al, 2021; McMurry et al, 2005). Another recent study has predicted that little NPF should occur in polluted megacities due to the high condensation sink (CS) (Kulmala et al, 2017); by contrast, observations show that NPF in these areas are frequent and more intense than in clean environments (Deng et al, 2020). This discrepancy underlines an incomplete understanding of NPF in polluted and usually chemically complex environments

Methods

Results

Conclusion