High secondary formation of nitrogen-containing organics (NOCs) and its possible link to oxidized organics and ammonium

Abstract

Highlights 19 Nitrogen-containing organics (NOCs) were highly internally mixed with photochemically 20 produced secondary oxidized organics 21  More than 50% of NOCs were well predicted by secondary formation from these 22 oxidized organics and ammonium 23  Higher relative humidity and particle acidity facilitated the formation of NOCs 24 2 Abstract 25Nitrogen-containing organic compounds (NOCs) substantially contribute to light 26 absorbing organic aerosols, although the atmospheric processes responsible for the secondary 27 formation of these compounds are poorly understood. In this study, seasonal atmospheric 28 processing of NOCs were investigated by single particle mass spectrometry in urban 29Guangzhou from 2013-2014. The relative abundance of NOCs was found to be strongly 30 enhanced by internal mixing with the photochemically produced secondary oxidized organics 31 (such as formate, acetate, pyruvate, methylglyoxal, glyoxylate, oxalate, malonate and 32 succinate). Furthermore, the co-occurrence of NOCs with ammonium was also observed. 33Interestingly, the relative abundance of NOCs was inversely correlated with ammonium, while 34 their number fractions were positively correlated. Multiple linear regression analysis and 35 positive matrix factorization analysis were performed to predict the relative abundance of NOCs 36 generated from oxidized organics and ammonium. Both results showed close associations (R 2 > 37 0.7, p < 0.01) between the predicted NOCs and the observed values. Increased humidity and 38 higher particle acidity were found to promote the production of NOCs. Higher relative 39 contributions of NOCs were observed in summer and autumn, in comparison to spring and 40 winter, due to the relatively higher contribution of oxidized organics and NH3/NH + 4 in summer 41 and autumn periods. To the best of our knowledge, this is the first direct field observation study 42 establishing a close association between NOCs and both oxidized organics and ammonium. 43These findings have substantial implications on the role of ammonium in the atmosphere, 44 particularly in models predicting the evolution and deposition of NOCs. 45 3 https://doi.

Factors Influencing the Molecular Compositions and Distributions of Atmospheric Nitrogen‐Containing Compounds

“…In the current study, aliphatic NOCs, which were positively correlated with OH radicals in the ESI+ pattern, were more than the NOCs corresponding to the ESI– pattern; this finding suggests the important effects of OH radicals on the formation of reduced NOCs. This is consistent with the results of field observations conducted in Shanghai and Guangzhou, which reported the formation of a large amount of secondary NOCs related to oxidized organics and ammonium (Wang et al., 2010; Zhang, Lian, et al., 2020). Additionally, OH‐initiated photo‐oxidation processes will accelerate the formation of aliphatic NOCs with reduce nitrogen atoms, but result in the photodecomposition of organic nitrates and reduced CHON+ compounds with small H/C ratios and greater O/C ratios, compared with aliphatic NOCs.…”

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

“…The particles containing 26 CN − and 42 CNO − were considered to be representative of the organic nitrogen-containing particles (Pratt et al, 2011). In addition, the 73 C 3 H 5 O − 2 and 89 HC 2 O − 4 ions were designated as glyoxylate and oxalate markers, respectively (Cheng et al, 2017;Zhang et al, 2020). It should be noted that HP-SPAMS measurements cannot provide the quantitative mass concentrations of amines and related chemical species due to the size-dependent transmission efficiencies of particles through aerodynamic lens and composition dependent matrix effect (Cheng et al, 2018(Cheng et al, , 2021Gong et al, 2021).…”

Comprehensive study about the heterogeneous conversion of NH3on nanoscale TiO2particles: insight into the mechanism and atmospheric implications

“…[25][26][27][28][29][30] In addition, NH 3 has been found to react with carbonyl compounds in secondary organic aerosol (SOA) which results in the formation of nitrogen-containing organic compounds (NOC) and significantly affects regional air quality. [31][32][33][34][35][36][37] These results demonstrate that besides acid-base neutralization reactions in the gas phase, heterogeneous and multiphase reactions of ammonia should also be investigated systematically.…”