[Characteristics and Sources of VOCs Pollution in Typical Regions of Tianjin]

The characterization and source apportionment of atmospheric volatile organic compounds (VOCs) were investigated based on high-resolution online monitoring data observed from April to September in 2024 at typical sites in Tianjin of the Central Urban Area and Binhai New Area. The results showed that the average concentrations of VOCs in different areas were ranked as follows: Central Urban Area (32.95 μg·m^-3) < Nanjiang Port (53.49 μg·m^-3) < Lingang Industrial Zone (61.16 μg·m^-3) < Binhai Development Zone (62.18 μg·m^-3). The chemical compositions of VOCs were alkanes, aromatics, alkenes, and alkynes, accounting for 62.46%-71.45%, 19.39%-25.87%, 6.35%-14.48%, and 0.69%-3.67% of VOCs concentration on average, respectively. Higher alkane proportions were observed in Nanjiang Port and Binhai Development Zone, while the highest proportions of alkenes and aromatics were observed in the Central Urban Area and Lingang Industrial Zone, respectively. The ozone formation potential (OFP) values were ranked as follows: Central Urban Area (98.81 μg·m^-3) < Nanjiang Port (132.46 μg·m^-3) < Binhai Development Zone (154.36 μg·m^-3) < Lingang Industrial Zone (179.18 μg·m^-3). Aromatics and alkenes were the main contributors to OFP, accounting for 30.73%-51.48% and 25.61%-48.32%, respectively. Aromatics had the highest contribution to OFP in Binhai Development Zone, Lingang Industrial Zone, and Nanjiang Port, while alkenes had the highest contribution to OFP in the Central Urban Area. The ratio of m/p-xylene to ethylbenzene indicated that VOCs were mainly emitted locally in the Central Urban Area, Binhai Development Zone, and Lingang Industrial Zone, while the long-distance transmission of VOCs had a certain impact on Nanjiang Port. Positive matrix factorization was applied to estimate VOCs source contributions, and the results showed that the sources of VOCs were significantly different in different regions. Gasoline vehicles, LPG volatilization, petrochemical industry emissions, NG volatilization, solvent usage, natural sources, and combustion were identified as major sources of VOCs in the Central Urban Area, accounting for 24.5%, 19.4%, 13.9%, 13.1%, 11.8%, 9.5%, and 7.8%, respectively. While in Binhai New Area, the main sources of VOCs contributions were diesel mobile sources, LPG volatilization, gasoline vehicles, solvent usage, food processing, petrochemical industry emissions, and combustion, with the contributions of three regions being 17.8%-37.3%, 17.2%-22.1%, 14.5%-18.8%, 6.4%-21.7%, 5.7%-23.3%, 6.9%-7.8%, and 2.8%-9.2%, respectively. Future attention should focus on gasoline vehicles, LPG volatilization, NG volatilization, and solvent usage in the Central Urban Area, while diesel mobile sources, LPG volatilization, gasoline vehicles, solvent usage, food processing, and petrochemical industry emissions were the key prevention and control sources in Binhai New Area in order to further prevent and control ozone in Tianjin.