Preprints
https://doi.org/10.5194/acp-2022-116
https://doi.org/10.5194/acp-2022-116
 
08 Mar 2022
08 Mar 2022
Status: this preprint is currently under review for the journal ACP.

Variations and sources of volatile organic compounds (VOCs) in urban region: insights from measurements on a tall tower

Xiao-Bing Li1,2, Bin Yuan1,2, Sihang Wang1,2, Chunlin Wang3,4, Jing Lan3,4, Zhijie Liu1,2, Yongxin Song1,2, Xianjun He1,2, Yibo Huangfu1,2, Chenglei Pei5,6,7,8, Peng Cheng9, Suxia Yang1,2, Jipeng Qi1,2, Caihong Wu1,2, Shan Huang1,2, Yingchang You1,2, Ming Chang1,2, Huadan Zheng10, Wenda Yang9, Xuemei Wang1,2, and Min Shao1,2 Xiao-Bing Li et al.
  • 1Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China
  • 2Guangdong-Hongkong-Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou 511443, China
  • 3Guangzhou Climate and Agrometeorology Center, Guangzhou, 511430, China
  • 4Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519082, China
  • 5State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China
  • 6CAS Center for Excellence in Deep Earth Science, Guangzhou, 510640, China
  • 7University of Chinese Academy of Sciences, Beijing 100049, China
  • 8Guangzhou Ecological and Environmental Monitoring Center of Guangdong Province, Guangzhou 510060, China
  • 9Institute of Mass Spectrometer and Atmospheric Environment, Jinan University, Guangzhou 510632, Guangdong, China
  • 10Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, and Department of Optoelectronic Engineering, Jinan University, Guangzhou, 510632, China

Abstract. Volatile organic compounds (VOCs) are key precursors of ozone and particulate matter that are the two dominant air pollutants in urban environments. However, compositions and sources of VOCs in urban air aloft were rarely reported by far. To address this matter, highly time-resolved measurements of VOCs were made by proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) at a 450-m platform on the Canton Tower in Guangzhou, China. A combination of in-situ measurements and modeling techniques was used to characterize variations and sources of VOCs. Five sources were identified from positive matrix factorization (PMF) analysis, namely daytime-mixed (e.g., biogenic emissions and secondary formation), visitor-related (e.g., human breath and volatilization of ethanol-containing products), vehicular+industrial, regional transport, and volatile chemical product (VCP)-dominated (i.e., volatilization of personal care products), contributing on average to 22 %, 30 %, 28 %, 10 %, and 11 % of total VOC (TVOC) mixing ratios, respectively. We observe that contributions of the visitor-related source, mainly composed of ethanol, followed well with the variation patterns of visitor number on the tower. The VCP-dominated source only had an average contribution of ~5.7 ppb during the campaign, accounting for a small fraction (11 %) of TVOC mixing ratios. However, large fractions of some VOC species, e.g., monoterpenes (49 %), were attributed to the VCP-dominated source, indicating significant contributions of VCPs to ambient concentrations of these species in urban environments. Vertical profiles of air pollutants (including NOx, ozone, Ox, and PM2.5), measured at 5 m, 118 m, 168 m, and 488 m, exhibited more evident gradients at night than in the daytime owing to stronger stability of the nocturnal boundary layer. Mixing ratios of VOC species during the nighttime generally decreased with time when the 450-m platform was located in the nocturnal residual layer and significantly increased when impacted by emissions at ground. The results in this study demonstrated composition characteristics and sources of VOCs in urban air aloft, which could provide valuable implications in making control strategies of VOCs and secondary air pollutants.

Xiao-Bing Li et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on acp-2022-116', Anonymous Referee #1, 28 Mar 2022
  • RC2: 'Comment on acp-2022-116', Anonymous Referee #2, 01 May 2022

Xiao-Bing Li et al.

Xiao-Bing Li et al.

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Short summary
High time-resolution measurements of volatile organic compounds (VOCs) were made using an online mass spectrometer at a 600-m tall tower in urban region. Compositions, temporal variations, and sources of VOCs were quantitatively investigated in this study. We find that VOCs measurements in urban region aloft could better characterize source characteristics of anthropogenic emissions. Our results could provide important implications in making future control strategies of VOCs.
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