Abstract
Volatile organic compounds (VOCs) are important precursors of photochemical ozone and secondary organic aerosol (SOA). Here, hourly variations of ambient VOCs were monitored with an online system at an urban site (Panyu, PY) in the Pearl River Delta region during August–September of 2020 in order to identify reactive VOC species and major sources of VOCs, OH loss rate (LOH), SOA formation potential (SOAFP), and corresponding emission source regions. The average concentration of VOCs at PY was 31.80 ± 20.82 ppbv during the campaign. The C2–C5 alkanes, aromatics, and ≥C6 alkanes contributed for the majority of VOC, alkenes and aromatics showed the highest contribution to LOH and SOAFP. Further, m/p-xylene, propene, and toluene were found to be the top three most reactive anthropogenic VOC species, with respective contributions of 11.6%, 6.1%, and 5.8% to total LOH. Toluene, m/p-xylene, and o-xylene constituted a large fraction of calculated SOAFP. Seven major sources were identified by using positive matrix factorization model. Vehicle exhaust made the most significant contribution to VOCs, followed by liquefied petroleum gas and combustion sources. However, industrial-related sources (including industrial solvent use and industrial process emission) had the largest contribution to LOH and SOAFP. By combining source contribution with wind direction and wind speed, the regions of different sources were further identified. Based on high-resolution observation data during ozone pollution, this study clearly exhibits key reactive VOC species and the major emission regions of different VOC sources, and thus benefits the accurate emission control of VOCs in the near future.
Highlights
Volatile organic compounds (VOCs) are important precursors of ozone and secondary organic aerosols (SOA) [1,2,3,4,5,6]
The percentages of C2 –C5 alkanes and ≥C6 alkanes decreased, from 48.2% and 14.5% for VOCs to 12.0% and 10.7% for LOH, indicating that alkenes and aromatics contributed more to ozone formation; priority control of reactive alkenes and aromatics is key to ozone pollution control
To explore the reactive VOC species and identify the major sources of VOCs, LOH, SOA formation potential (SOAFP), and corresponding emission regions in the urban Pearl River Delta (PRD) during severe ozone pollution, the ambient VOCs were monitored with a high-resolution online system in central
Summary
Volatile organic compounds (VOCs) are important precursors of ozone and secondary organic aerosols (SOA) [1,2,3,4,5,6]. Ozone has long been known to cause adverse effects on human health [7,8,9] and has the potential to damage crops and vegetation [10,11,12]. It is an important tropospheric greenhouse gas, with an estimated globally averaged radiative forcing of 0.40 ± 0.20 W m−2 , and directly contributes to global warming [13]. As the important precursors of ozone and SOA, VOCs play an important role in photochemical smog, particulate pollution, and human health impacts
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