Process-Resolved VOC Source Profiles from Typical Industries in Deyang and Their Implications for Regional Composite Profiles in the Chengdu–Chongqing Region

Volatile organic compound (VOC) emissions exhibit strong process-level heterogeneity, yet regional source characterization still commonly relies on sector-average profiles, introducing substantial uncertainty into source identification and control prioritization. In this study, process-resolved VOC source profiles were established for five representative industrial sectors in Deyang, a typical industrial city in the Chengdu–Chongqing region, including pharmaceutical manufacturing, industrial coating, chemical industry, food manufacturing, and the textile industry. A total of 19 organized emission samples were collected from 9 enterprises, and 123 VOC species were quantified. These measured profiles were further integrated with literature-derived profiles and a bottom-up emission inventory to construct an emission-weighted regional composite source profile for 17 major industrial sectors. An emission-based hydroxyl radical (OH) reactivity-weighted framework was then introduced to compare mass-dominant and chemically dominant VOC sources. The results showed pronounced process- and sector-specific differences in composition. Pharmaceutical manufacturing was mainly dominated by oxygenated VOCs (OVOCs), industrial coating by low-carbon halocarbons, the chemical industry by methanol and reactive low-carbon compounds, food manufacturing by alkenes and OVOCs, and the textile industry by light alkanes. At the regional scale, industrial VOC emissions were dominated by OVOCs (35.67%), followed by alkanes (19.01%) and aromatics (15.99%). Ethyl acetate, 1,4-dioxane, 1,1,2,2-tetrachloroethane, and m/p-xylene were identified as the most abundant species. However, OH reactivity was largely dominated by alkenes, and substantial discrepancies were observed between emission contribution and OH-reactivity-weighted contribution across sectors. In particular, the chemical industry contributed 21.10 ± 8.43% of reactive organic gas emissions but 28.82 ± 11.61% of OH-weighted emissions, whereas printing contributed 13.55 ± 13.42% of mass emissions but only 7.66 ± 13.08% of OH-weighted emissions. These findings demonstrate that regional VOC management should move beyond bulk mass reduction and prioritize high-reactivity sectors and process units to maximize O3 mitigation benefits.