Diverse mixing states of amine-containing single particles in Nanjing, China

Qi En Zhong,Dafeng Ge,Wei Nie,Suxia Yang,Lei Wang,Aijun Ding,Duohong Chen,Xuguang Chi,Chunlei Cheng,Zhen Zhou,Zaihua Wang,Mei Li,Lei Li,Yuanyuan Li

doi:10.5194/acp-21-17953-2021

Abstract

Abstract. The mixing states of particulate amines with different chemical components are of great significance in studying the formation and evolution processes of amine-containing particles. In this work, the mixing states of single particles containing trimethylamine (TMA) and diethylamine (DEA) are investigated using a high-performance single-particle aerosol mass spectrometer located in Nanjing, China, in September 2019. TMA- and DEA-containing particles accounted for 22.8 % and 5.5 % of the total detected single particles, respectively. The particle count and abundance of the TMA-containing particles in the total particles notably increased with enhancement of ambient relative humidity (RH), while the DEA-containing particles showed no increase under a high RH. This result suggested the important role of RH in the formation of particulate TMA. Significant enrichments of secondary organic species, including 43C2H3O+, 26CN−, 42CNO−, 73C3H5O2-, and 89HC2O4-, were found in DEA-containing particles, indicating that DEA-containing particles were closely associated with the aging of secondary organics. The differential mass spectra of the DEA-containing particles showed a much higher abundance of nitrate and organic nitrogen species during the nighttime than during the daytime, which suggested that the nighttime production of particulate DEA might be associated with reactions of gaseous DEA with HNO3 and/or particulate nitrate. In the daytime, the decrease in DEA-containing particles was observed with the enrichment of oxalate and glyoxylate, which suggested a substantial impact of photochemistry on the aging process of DEA-containing particles. Furthermore, more than 80 % of TMA- and DEA-containing particles internally mixed with nitrate, while the abundance of sulfate was higher in the DEA-containing particles (79.3 %) than in the TMA-containing particles (55.3 %). This suggested that particulate DEA existed both as nitrate and sulfate aminium salts, while the particulate TMA primarily presented as nitrate aminium salt. The different mixing states of the TMA- and DEA-containing particles suggested their different formation processes and various influencing factors, which are difficult to investigate using bulk analysis. These results provide insights into the discriminated fates of organics during the evolution process in aerosols, which helps to illustrate the behavior of secondary organic aerosols.

Highlights

Amines are ubiquitous organic components in aerosols and have a wide range of sources, including animal husbandry, industrial emissions, vehicle exhaust, biomass burning, vegetation emissions, and ocean emissions (Ge et al, 2011b; Facchini et al, 2008; Youn et al, 2015)
The TMA- and DEA-containing particles exhibited similar temporal trends at a lower particle count, their increasing peaks appeared at different periods, suggesting that the reasons for their increase in the particle count were different
The relative peak areas (RPAs) of the DEA showed no difference in reaction to the relative humidity (RH) change during the entire sampling period

Summary

Introduction

Amines are ubiquitous organic components in aerosols and have a wide range of sources, including animal husbandry, industrial emissions, vehicle exhaust, biomass burning, vegetation emissions, and ocean emissions (Ge et al, 2011b; Facchini et al, 2008; Youn et al, 2015). Ambient relative humidity (RH; Rehbein et al, 2011; Zhang et al, 2012), temperature (Huang et al, 2012), particle acidity (Pratt et al, 2009; Rehbein et al, 2011), amine–ammonium exchange (Chan and Chan, 2013; Chu and Chan, 2017; Qiu et al, 2011), and oxidants (Tang et al, 2013; Price et al, 2016) all influence the formation of particulate amines. According to the seasonal distributions of amines during the summer and winter, low temperature was found to be favorable for the partitioning of gaseous amines into particles. According to the seasonal distributions of amines during the summer and winter, low temperature was found to be favorable for the partitioning of gaseous amines into particles. Huang et al (2012) found that the number fraction (Nf) of amine-containing particles during winter was 4 times higher than that during summer

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Conclusion