Characteristics and Source Apportionment of Atmospheric VOCs in the Nanjing Industrial Area in Autumn

Abstract

Atmospheric volatile organic compounds (VOCs) were continuously monitored via an online GC-FID/MS system in Nanjing during the autumn of 2018 to analyze the chemical characteristics, ozone formation potential (OFP), and potential sources of VOCs in this industrial region. During the sampling period, the average concentration of atmospheric total VOCs (TVOCs) was (64.3±45.6)×10-9. Alkanes were the most predominant VOC compound, accounting for 33.1% of the TVOC mass, followed by oxygenated volatile organic compounds (OVOCs, 22.3%) and halogenated hydrocarbons (21.8%). The diurnal cycles of VOCs revealed "bimodal" distributions. The higher concentrations of VOCs observed at 06:00-07:00 and 18:00-20:00 were attributed to the intense traffic emissions and meteorological conditions. Furthermore, maximum incremental reaction (MIR) analysis was used to estimate OFP of VOCs. The results showed that the calculated OFP in Nanjing was 267.1 μg·m-3. Aromatic hydrocarbons and alkenes were the dominant contributors to OFPs, which accounted for 55.2% and 20.8% to the total OFPs, respectively. Finally, five potential sources of VOCs were quantified by the positive matrix factorization model, including traffic emissions (34%), industrial emissions (19%), liquefied petroleum gas (LPG) emissions (17%), usage of paints and solvents (16%), coal combustion, and biomass burning (14%). These findings suggested that control of vehicle emissions and industrial sources would be an important way to reduce VOC concentrations and improve air quality in Nanjing.