Integrating ambient carbonyl compounds provides insight into the constrained ozone formation chemistry in Zibo city of the North China Plain.

Quantifying the impact of carbonyl compounds (carbonyls) on ozone (O 3) photochemical formation is crucial to formulating targeted O 3 mitigation strategies. To investigate the emission source of ambient carbonyls and their integrated observational constraint on the impact of O 3 formation chemistry, a field campaign was conducted in an industrial city (Zibo) of the North China Plain from August to September 2020. The site-to-site variations of OH reactivity for carbonyls were in accordance with the sequence of Beijiao (BJ, urban, 4.4 s⁻¹) > Xindian (XD, suburban, 4.2 s⁻¹) > Tianzhen (TZ, suburban, 1.6 s⁻¹). A 0-D box model (MCMv3.3.1) was applied to assess the O 3 -precursor relationship influenced by measured carbonyls. It was found that without carbonyls constraint, the O 3 photochemical production of the three sites was underestimated to varying degrees, and the biases of overestimating the VOC-limited degree were also identified through a sensitivity test to NO x emission changes, which may be associated with the reactivity of carbonyls. In addition, the results of the positive matrix factorization (PMF) model indicated that the main source of aldehydes and ketones was secondary formation and background (81.6% for aldehydes, 76.8% for ketones), followed by traffic emission (11.0% for aldehydes, 14.0% for ketones). Incorporated with the box model, we found that biogenic emission contributed the most to the O 3 production at the three sites, followed by traffic emission as well as industry and solvent usage. Meanwhile, the relative incremental reactivity (RIR) values of O 3 precursor groups from diverse VOC emission sources featured consistencies and differences at the three sites, which further highlights the importance of the synergetic mitigation of target O 3 precursors at regional and local scales. This study will help to provide targeted policy-guiding O 3 control strategies for other regions. [Display omitted] • The effect of carbonyls on O 3 formation at three sites was comprehensively investigated. • Incorporating PMF and OBM approach is applied to quantify the RIR of VOC sources. • The overestimation of VOC-limited degree was found when carbonyls unconstrained. [ABSTRACT FROM AUTHOR]