Pollution Characteristics of Atmospheric Carbonyl Compounds in a Large City of Northern China

Abstract

To better understand the pollution characteristics and formation mechanisms of atmospheric carbonyl compounds, continuous measurements of carbonyl compounds in Jinan were taken for one month at a sampling frequency of 2 h. The sources, pollution characteristics, and concentration changes of carbonyl compounds during the summers of 2018 and 2020 were compared. The total concentrations of carbonyl compounds were 10.51 ± 0.13 ppbV and 6.30 ± 1.08 ppbV in 2018 and 2020, respectively. In both years, formaldehyde, acetone, and acetaldehyde were the major carbonyls. Diurnal variations and correlation analyses showed that exhaust emissions from motor vehicles during peak traffic periods significantly contributed to the concentrations of carbonyl compounds in Jinan, with formaldehyde exhibiting net production. The ratio of formaldehyde/acetaldehyde (C1/C2) was 2.64 in 2018 and 2.03 in 2020, indicating that carbonyl compounds are jointly affected by anthropogenic sources and photochemical reactions. Master Chemical Mechanism model analyses showed that the formation of formaldehyde in Jinan was controlled by RO + O2 reactions, and formaldehyde was mainly consumed via photolysis and its reaction with the hydroxyl radical. In situ photochemistry can further promote formaldehyde production. The comparison of the reactivities of different carbonyl compounds revealed that formaldehyde, acetaldehyde, butyraldehyde, and propionaldehyde play an important role in hydroxyl radical reactions and ozone generation. Among all the measured carbonyl compounds, benzaldehyde contributed the most to secondary organic aerosols (SOAs). Overall, this study provides new insights into the formation mechanisms of carbonyl compounds as well as their pollution characteristics.

Molecular Characteristics, Sources, and Health Risk Assessment of Gaseous Carbonyl Compounds in Residential Indoor and Outdoor Environments in a Megacity of Northwest China

“…Figure 1 and Table S4 present the molecular distributions of outdoor CCs at HS, QJ, and XY. Consistent with previous studies [42][43][44][45][46][47][48], acetone (A3K), acetaldehyde (C2), and formaldehyde (C1) were the most abundant compounds in CCs at all three outdoor sites. The concentrations of outdoor A3K, C2, and C1 were 9.6-21.2 μg/m 3 , 5.7-12.2 μg/m 3 , 6.0-9.7 μg/m 3 , respectively, and the sum of LMW C1, A3K, and C2 accounted for 37.3-66.3% of the total CCs.…”