08 Aug 2022
08 Aug 2022
Status: this preprint is currently under review for the journal ACP.

Formation and impacts of nitryl chloride in Pearl River Delta

Haichao Wang1,4, Bin Yuan2,3, E Zheng2,3, Xiaoxiao Zhang2,3, Jie Wang1, Keding Lu5,6, Chenshuo Ye2,3, Lei Yang2,3, Shan Huang2,3, Weiwei Hu7, Suxia Yang2,3, Yuwen Peng2,3, Jipeng Qi2,3, Sihang Wang2,3, Xianjun He2,3, Yubin Chen2,3, Tiange Li2,3, Wenjie Wang2,8, Yibo Huangfu2,3, Xiaobing Li2,3, Mingfu Cai2,3, Xuemei Wang2,3, and Min Shao2,3 Haichao Wang et al.
  • 1School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai, 519082, China
  • 2Institute for Environmental and Climate Research, Jinan University, Guangzhou 511443, China
  • 3Guangdong–Hong Kong–Macau Joint Laboratory of Collaborative Innovation for Environmental Quality, Guangzhou, 511443, China
  • 4Guangdong Provincial Observation and Research Station for Climate Environment and Air Quality Change in the Pearl River Estuary, Key Laboratory of Tropical Atmosphere-Ocean System, Ministry of Education, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, 519082, China
  • 5State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China
  • 6The State Environmental Protection Key Laboratory of Atmospheric Ozone Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, China
  • 7State 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
  • 8Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany

Abstract. Here we present a field measurement of ClNO2 (nitryl chloride) and N2O5 (dinitrogen pentoxide) by a state-of-the-art instrument at a regional site in Pearl River Delta during a photochemical pollution season from Sept. 26th to Nov. 17th, 2019. Three patterns of air masses are sampled during this campaign, including the dominating air masses from north and northeast urban regions (Type A), the southeast coast (Type B) and the South China Sea (Type C). The concentration of ClNO2 and N2O5 were observed much higher in Type A and B than those in Type C, indicated the urban nighttime chemistry is more active than the background marine regions. Two key parameters that regulating ClNO2 formations, N2O5 uptake coefficient and ClNO2 production yield, were estimated by measured parameters, and the performance of the previously derived parameterizations were assessed. We find the ClNO2 formation was limited by the N2O5 uptake rather than N2O5 source at this site. By examining the relationship of particulate chloride and other species, we implied that anthropogenic emissions (e.g., biomass burning) rather than sea salt particles dominate the origin of particulate chloride, despite the site is only about 100 km away from the ocean.  Model simulations showed the chloride radical liberated by ClNO2 photolysis during the next day had a small increase in concentrations of OH, HO2 and RO2 radicals, as well as minor contributions to RO2 radical and O3 formation (<5 %, on daytime average) in all the three types of air masses. Relative higher contributions were observed in Type A and B. The overall low contributions of ClNO2 to ozone pollution are consistent with those reported recently from wintertime observations in China (included Shanghai, Beijing, Wangdu and Mt. Tai). This may be attributed to: (1) Relative low particle mass concentration limited ClNO2 formation; (2) Other reactions channels had larger radical formation rate during the ozone pollution episodes and weakened the ClNO2 contribution indirectly. The results provided scientific insights into the role of nighttime chemistry in photochemical pollution under various scenarios in coastal areas.

Haichao Wang 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-2022-408', Anonymous Referee #2, 17 Aug 2022
  • RC2: 'Comment on acp-2022-408', Anonymous Referee #1, 30 Aug 2022

Haichao Wang et al.

Haichao Wang et al.


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Short summary
We present an intensive field measurement of ClNO2 in Pearl River Delta in 2019. Large variation of the level, formation and atmospheric impacts of ClNO2 was found in different air masses. ClNO2 formation was limited by the particulate chloride (Cl-) and aerosol surface area. Our results reveal that Cl- originated from various anthropogenic emissions rather than sea source, and show minor contribution to the O3 pollution.