Characterization and source analysis of carbonyl compounds in a rural area of north China Plain: Results from 1-year continuous observations

Carbonyl compounds are significant in atmospheric chemistry and human health, yet their sources, especially in rural areas, remain incompletely characterized. Long-term measurements (June 2020–July 2021) at a rural site in the North China Plain (NCP) identified formaldehyde, acetaldehyde, and acetone as the dominant carbonyls, collectively accounting for 71 % of the total. Concentrations exhibited distinct seasonal patterns, with the highest levels observed for all three compounds during autumn. Analysis of C1/C2 ratios and correlation analysis indicated anthropogenic emissions as the primary source overall. Notably, during autumn, strong mutual correlations among formaldehyde, acetaldehyde, and acetone were observed, contrasting with weaker correlations to CO and O 3 . Supplementary experiments confirmed that mechanical corn stover crushing releases substantial amounts of carbonyls. These convergent findings demonstrate that large-scale seasonal agricultural activities, particularly corn stover crushing and agricultural machinery during harvest periods, constitute a major and previously underappreciated source of carbonyl emissions in the NCP region, necessitating greater attention in emission inventories and mitigation strategies. Furthermore, integrated lifetime cancer risk (ILTCR) and hazard quotient (HQ) assessments indicated that formaldehyde concentrations pose a potential lifetime carcinogenic risk to the local population. • Autumn OVOCs hit 76.3 μg/m 3 ; formaldehyde, acetaldehyde, acetone constituted 71 %. • Corn stover crushing emitted substantial carbonyls, with acetaldehyde as top species. • Formaldehyde ILTCR > USEPA limits, especially during harvest farmer exposure.