C1-C2 alkyl aminiums in urban aerosols: Insights from ambient and fuel combustion emission measurements in the Yangtze River Delta region of China

Abstract

We measured low molar-mass alkyl aminiums (methylaminium, dimethylaminium, ethylaminium and diethylaminium) in urban aerosols in the Yangtze River Delta region of eastern China in August 2014 and from November 2015 to May 2016. After examining artifact formation on sample filters, methylaminium, dimethylaminium and ethylaminium concentrations were quantified. The three C1-C2 aminiums exhibited a unimodal size distribution that maximized between 0.56 and 1.0 μm. Their concentrations in PM were 5.7 ± 3.2 ng m, 7.9 ± 5.4 ng m and 20.3 ± 16.6 ng m, respectively, with higher concentrations during the daytime and in warm seasons. On new particle growth days, amine uptake to particles larger than 56 nm was barely enhanced. The molar ratios of individual aminium/NH in PM were on the order of 10 and 10. Aminiums were thus far less to out-compete ammonium (NH) in neutralizing acidic species in particle sizes down to 56 nm. Abundant nitrate (NO/SO molar ratio = ∼3) and its correlation to methylaminium and ethylaminium implied that nitrate might be more important aminium salt than sulfate in urban aerosols of this area. Direct measurement of particle-phase amine emission from coal and biomass burning showed that coal burning is an important atmospheric amine source, considering coal burning is top-ranked particulate matter source in China.

Particulate Amines in the Background Atmosphere of the Yangtze River Delta, China: Concentration, Size Distribution, and Sources

“…Previous studies reported contradictory conclusions on the relationship between amines and O 3 . For example, in Shen et al (2017), MA and DMA, were found to be positively correlated with O 3 in urban Nanjing, consistent with the present study, but Zhou et al (2019) found a negative correlation between amines and O 3 in urban Shanghai in summer of 2013, and no correlations were found in other seasons. Generally, amines in gaseous phase could be oxidized by oxidants such as O 3 and OH radical (Ge et al, 2011a;Nielsen et al, 2012;Tong et al, 2020), while the amines in particle phase might fail to show a negative correlation with O 3 .…”

“…Amines were also found to be correlated with secondary inorganic components including , , and and K + , as well as levoglucosan, which is a key tracer of a biomass burning plume (Pachon et al, 2013), indicating that anthropogenic activities such as biomass burning were the possible sources of amines in the study site (Zheng et al, 2015). Amines were also positively correlated with the trace gas pollutants such as SO 2 , NH 3 , HNO 3 , HCl, and HONO, consistent with the strong correlation between amines and SO 2 that was previously reported (Shen et al, 2017). Interestingly, MA, DMA, and DEA positively correlated with O 3 , which was considered to be a species with oxidizing capacity (Ge et al, 2011a).…”

“…Previous studies had measured atmospheric amines in urban, rural, coastal and marine areas (Kieloaho et al, 2013;Shen et al, 2017;Liu et al, 2018;Zhou et al, 2019). It is recognized that in coastal regions and marine areas, the main sources of amines are biological activities on the ocean surface, rather than industry and combustion sources (Facchini et al, 2008;Müller et al, 2009), which is different from urban areas (Zhou et al, 2019) where industrial sources dominate (Shen et al, 2017). For example, higher DEA and TMA were observed on the days with stronger biological activities compared to the days with reduced biological activities in the North Atlantic.…”

Indoor acids and bases

“…[431][432][433] More generally, they can neutralize strong acids in outdoor air. For example, Shen et al 434 found that amines, emitted during the burning of coal in the Yangtze River Delta region of China, react with nitric and sulfuric acids to form aminium salts (the salt that results from an amine reacting with a strong acid). Aminium nitrates were more abundant than aminium sulfates, with average concentrations of methylaminium, dimethylaminium, and ethylaminium salts in aerosol particles of 6 ± 3 ng/m 3 , 8 ± 5 ng/m 3 , and 20± 17 ng/m 3 , respectively.…”

Characteristics and sources of amine-containing particles in the urban atmosphere of Liaocheng, a seriously polluted city in North China during the COVID-19 outbreak

“…The mass concentrations and temporal distributions of amines in Chinese megacities (e.g., Guangzhou, Nanjing and Shanghai) have been studied extensively based on the traditional filter sampling methods ( Cheng et al, 2020 ; Liu et al, 2018 ; Shen et al, 2017 ). However, the traditional off-line sampling is time consuming and the samples may be reacted with each other during the sampling process.…”