Measurement and minutely-resolved source apportionment of ambient VOCs in a corridor city during 2019 China International Import Expo episode

In this study, real-time measurement of Volatile Organic Compounds (VOCs) was conducted at an urban site in Changzhou, a typical corridor city the Yangtze River Delta (YRD) region China, by Proton−Transfer−Reaction Time−of−Flight Mass Spectrometry (PTR−ToF−MS) during 2019 China International Import Expo (CIIE) episode. An improved method based on Air Quality Index (AQI) value is applied to identify polluted and clean periods. Diurnal pattern VOC levels revealed elevated photochemical reactivity Five sources were identified Positive Matrix Factorization (PMF) model, including secondary formation (22.71 ± 12.33%), biogenic (21.50% 11.76%), solvent usage (20.50 10.07%), vehicle exhaust (18.32 8.32%), industrial process fuel (16.96 13.21%). The mean contribution vehicular 10.84% higher nighttime than daytime under days. source contributed more periods, while presented opposite. Spatial analysis displayed that concentration S SSE. terms regional transport, short-distance air masses from northeast south within YRD led high derived ocean might affect entire region. Stringent emission control policies enforced over for CIIE provided excellent opportunity determine source-receptor response. As joint area, level Changzhou exhibited substantial reduction amounts emitted showed biggest decrease (−58%). findings study highlight superiority time-resolved data identifying dynamic variation (with change time wind) intensities.