Observation and Source Apportionment of Atmospheric Alkaline Gases in Urban Beijing

Abstract

Alkaline gases, including NH3, C1–3-amines, C1–3-amides, and C1–3-imines, were measured in situ using a water cluster-CIMS in urban Beijing during the wintertime of 2018, with a campaign average of 2.8 ± 2.0 ppbv, 5.2 ± 4.3, 101.1 ± 94.5, and 5.2 ± 5.4 pptv, respectively. Source apportionment analysis constrained by emission profiles of in-use motor vehicles was performed using a SoFi-PMF software package, and five emission sources were identified as gasoline-powered vehicles (GV), diesel-powered vehicles (DV), septic system emission (SS), soil emission (SE), and combustion-related sources (CS). SS was the dominant NH3 source (60.0%), followed by DV (18.6%), SE (13.1%), CS (4.3%), and GV (4.0%). GV and DV were responsible for 69.9 and 85.2% of C1- and C2-amines emissions, respectively. Most of the C3-amines were emitted from nonmotor vehicular sources (SS = 61.3%; SE = 17.8%; CS = 9.1%). DV accounted for 71.9 and 34.1% of C1- and C2-amides emissions, respectively. CS was mainly comprised of amides and imines, likely originating from the pyrolysis of nitrogen-containing compounds. Our results suggested that motor vehicle exhausts can not only contribute to criteria air pollutants emission but also promote new particle formation, which has not been well recognized and considered in current regulations. Urban residential septic system was the predominant contributor to background NH3. Enhanced NH3 emissions from soil and combustion-related sources were the major cause of PM2.5 buildup during the haze events. Combustion-related sources, together with motor vehicles, were responsible for most of the observed amides and imines and may be of public health concern within the vicinity of these sources.

Estimates of Future New Particle Formation under Different Emission Scenarios in Beijing

“…Dimethylamine (DMA) was presumed to be the base solely responsible for particle formation, and the emissions of DMA are presumed to scale with those of NH 3 . Particle formation in Beijing and similar cities has indeed been shown to be driven by DMA; , however, should DMA concentrations decrease, other amines may drive NPF (such as monoethanolamine, an important amine during carbon capture for which we provide estimates of J A4B4 in Figure S2), or trimethylamine, which has recently been shown by source apportionment to have distinct sources from DMA . All VOCs are presumed to scale equally, both those capable and incapable of forming and growing new particles.…”

“…Particle formation in Beijing and similar cities has indeed been shown to be driven by DMA; 20 , 23 however, should DMA concentrations decrease, other amines may drive NPF (such as monoethanolamine, an important amine during carbon capture 50 for which we provide estimates of J A4B4 in Figure S2 ), or trimethylamine, which has recently been shown by source apportionment to have distinct sources from DMA. 51 All VOCs are presumed to scale equally, both those capable and incapable of forming and growing new particles. No other compounds (such as HNO 3 ) are considered to contribute to the particle growth.…”

A new advance in the pollution profile, transformation process, and contribution to aerosol formation and aging of atmospheric amines

“…Motor vehicle emission is one of the important mobile sources. 63,73,98 Feng et al observed that the widely used ethanol gasoline vehicles in Hebei Province, China can primarily emit EAs. 63 Yang et al further compared the amine emission strengths of different power sources, and found that the total emission strength of diesel trucks was the greatest followed by those of gasoline cars and natural gas cars.…”

A parameterization of sulfuric acid-dimethylamine nucleation and its application in three-dimensional modeling

“…A regional or global bottom-up emission inventory of DMA is currently lacking, mostly due to scarce direct measurements (Yang et al, 2022;Zhu et al, 2022). In previous 3D model studies, amine/NH3 emission ratios have often been used to estimate amine emissions due to the close correlation between NH3 and DMA emissions.…”