[Emission Characteristics and Ozone Formation Potential of VOCs from Mobile Sources in the Beijing-Tianjin-Hebei Region].

Mobile sources are the primary contributor of volatile organic compounds （VOCs） emissions from anthropogenic sources in the Beijing-Tianjin-Hebei Region. Establishing a detailed VOCs emission inventory and clarifying the ozone generation potential （OFP） and their active species is conducive to scientific control of mobile source pollution. Based on the activity level data of mobile sources in the Beijing-Tianjin-Hebei Region， combined with the emission factor method and related research on source profiles， an emission inventory of VOCs from mobile sources was established to identify the emission contribution of key sources and components. Additionally， the ozone generation potential of VOCs was estimated using the maximum incremental reactivity （MIR）. The results indicated that total VOCs emissions from mobile sources in the Beijing-Tianjin-Hebei Region in 2021 was 214.6 kt， with 28.5 kt from Beijing， 28.1 kt from Tianjin， and 158.0 kt from Hebei Province. The VOCs emissions from mobile sources in the Beijing-Tianjin-Hebei Region were dominated by on-road mobile sources， with a proportion of 93.15%， of which gasoline motor vehicles contributed 72.70% to the emissions. Among non-road mobile sources， construction machinery and agricultural machinery had notable annual VOCs emissions， accounting for 2.01% and 1.99%， respectively. Aromatics， alkanes， and alkenes were the components with the highest VOCs emissions from mobile sources in the region， while alkenes， aromatics， and OVOCs had the highest contributions to OFP， accounting for 91.96%. Ethylene， propylene， toluene， formaldehyde， 1，2，3-trimethylbenzene， 1-butene， acetaldehyde， 1，3-butadiene， isopentane， and propionaldehyde were the major reactive species of OFP in the Beijing-Tianjin-Hebei Region， contributing 69.49% to the total OFP. The top contributing sources of VOCs emissions and OFP in Beijing， Tianjin， and Hebei provinces were all gasoline motor vehicles， in addition to motorcycles， diesel motor vehicles， and civil aviation aircraft in Beijing； construction machinery and ships in Tianjin； and diesel motor vehicles and agricultural machinery in Hebei Province， which also contributed relatively high local VOCs emissions and OFP.