Characteristics and sources of volatile organic compounds (VOCs) in Shanghai during summer: Implications of regional transport

Liu, Yuehui; Wang, Hongli; Jing, Shengao; Gao, Yaqin; Peng, Yan; Lou, Shengrong; Cheng, Tiantao; Tao, Shiheng; Li, Li; Li, Yingjie; Huang, Dandan; Wang, Qian; An, Jingyu

doi:10.1016/j.atmosenv.2019.116902

Cited by 98 publications

(34 citation statements)

References 78 publications

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“…The detection limits for VOC species range from several tens to hundreds pptv, as listed in supporting information Table S1. A detailed description of the measurements can be found in our previous study (Liu et al, 2019; Wang et al, 2013 ) .…”

Section: Experimental Methodsmentioning

confidence: 99%

Estimation of Secondary Organic Aerosol Formation During a Photochemical Smog Episode in Shanghai, China

Wang

Gao

et al. 2020

JGR Atmospheres

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Secondary organic aerosols (SOA) are formed through diverse processes in the atmosphere, among which photochemical processing is one important pathway. SOA formation was studied based on one heavy photochemical smog episode in summer in Shanghai. During the pollution episode, ozone and organic carbon (OC) increased simultaneously with a strong positive correlation, which was complete opposite to the volatile organic compounds (VOCs) pattern but similar to that of VOC photochemical consumption. The OC evolution was explained well by a parameterization method based on the observation of OC and VOCs, and secondary OC (SOC) formation was derived, being comparable with the result based on elemental carbon (EC) tracer method. About 67% of SOC could be explained by the photochemical consumption of VOCs (mainly aromatics, ~93%) during the episode. The contribution of VOCs to SOC formation was also estimated from the available VOC emissions inventories, which was comparable with that based on VOCs observations in ambient. Some differences of VOC species contribution to SOC were found between the ambient observation‐based and the emission‐based results, and the contribution of C9 aromatics was underestimated in the emission inventory. This suggests that bias of speciation might exist in the current VOC emissions inventories. The present study highlights the importance of VOC oxidation for SOC formation in summer in Shanghai. More insights are needed to improve the accuracy of VOCs speciated emissions inventories.

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Section: Experimental Methodsmentioning

confidence: 99%

Estimation of Secondary Organic Aerosol Formation During a Photochemical Smog Episode in Shanghai, China

Wang

Gao

et al. 2020

JGR Atmospheres

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“…Cluster analyses of backward trajectories are widely used to determine a dominant air mass direction and potential origin direction of pollutants at the study sites (Hong et al, 2019;Liu et al, 2016a;Liu et al, 2019). In this study, the 24-h backward trajectories (1-h intervals) of air masses arriving 100 m above ground level were calculated using the MeteoInfoMap software.…”

Section: Cluster and Potential Source Contribution Function (Pscf) Analysismentioning

confidence: 99%

Spatiotemporal Variation, Sources, and Secondary Transformation Potential of VOCs in Xi’an, China

Song¹,

Li²,

Yang³

et al. 2020

Preprint

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Abstract. As a critical precursors of ozone (O3) and secondary organic aerosols, volatile organic compounds (VOCs) play a vital role in air quality, human health, and climate change. In this study, a campaign of comprehensive field observations and VOC grid sampling was conducted in Xi’an, China from June 20 to July 20, 2019 to identify the spatiotemporal concentration levels, sources, and secondary transformation potential of VOCs. During the observation period, the average VOC concentrations at the Chanba (CB), Di Huan Suo (DHS), Qinling (QL), and gridded sampling sites were 27.8 ± 8.9, 33.8 ± 10.5, 15.5 ± 5.8, and 29.1 ± 8.4 ppb, respectively. Vehicle exhaust was the primary source of VOC emissions in Xi’an, and the contributions of vehicle exhaust to VOCs at the CB, DHS, and QL sites were 41.3 %, 30.6 %, and 23.6–41.4 %, respectively. While industrial emissions were the second-largest source of VOCs in urban areas, contributions from ageing sources were high in rural areas. High potential source contribution function values primarily appeared in eastern and southern Xi’an near the sampling site, which indicates that Xi'an exhibits a strong local VOC source. Moreover, alkenes, aromatics, and oxygenated VOCs played a dominant role in secondary transformation, which is a major concern in reducing O3 pollution in Xi’an.

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“…Using the ground measurements, de Gouw (2005) developed a parameterized method to estimate VOC emissions from carbon monoxide (CO) emission inventories and emission ratio of VOCs to CO, assuming that VOCs and CO were coemitted from the same sources (specifically, from combustion sources). Unfortunately, this assumption was unsuitable for most regions of China, where VOCs were emitted from complex sources, and aromatics in particular arise from a variety of industrial processes (Liu et al, 2019; Wang et al, 2013). Chen et al (2010) modified the Taiwan Air Quality Model by correcting VOC emission inputs using ratios of observed VOCs and primary model results (Chen et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Observation Constrained Aromatic Emissions in Shanghai, China

Wang

Yan

et al. 2020

JGR Atmospheres

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Aromatics in the atmosphere are a large contributor to ozone and secondary organic aerosol formation and have an adverse impact on human health. Observation‐based emissions are urgently needed for air quality management and decision making due to the large uncertainties in the emissions inventories. Atmospheric aromatics were continuously observed at one urban site in Shanghai of China in 2015, which were compared with the simulations of the Community Multiscale Air Quality (CMAQ) model. Large differences were found in the temporal variations between the model and measurements, corroborating with previous studies that the current bottom‐up emission inventories are highly biased. We corrected the aromatic emissions biases of the emission inventories using the observations with the CMAQ simulations, with the assumption that the response relationship of the emissions input and aromatic concentrations was reasonable on a monthly basis in CMAQ simulations, suggesting that the results are dependent on the model performance. The resulting aromatic emissions exhibited clear monthly variations, increasing from 5.5 ± 2.1 Gg month−1 in February to 17.4 ± 7.7 Gg month−1 in July, being different from the flat monthly pattern in the current bottom‐up emissions inventory. Toluene, xylenes, and ethylbenzene dominated aromatic emissions, accounting for ~74% on average but with considerable monthly variations, which was different from the nearly uniform value of 77% throughout the whole year in the emissions inventory. These highly temporally resolved and speciated in situ aromatics measurements provide observation‐based constraints on aromatic emissions, which cannot be obtained from satellite measurements. This study proposes a top‐down emission estimation method constrained by ambient measurements.

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Characteristics and sources of volatile organic compounds (VOCs) in Shanghai during summer: Implications of regional transport

Cited by 98 publications

References 78 publications

Estimation of Secondary Organic Aerosol Formation During a Photochemical Smog Episode in Shanghai, China

Estimation of Secondary Organic Aerosol Formation During a Photochemical Smog Episode in Shanghai, China

Spatiotemporal Variation, Sources, and Secondary Transformation Potential of VOCs in Xi’an, China

Observation Constrained Aromatic Emissions in Shanghai, China

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