Long-term winter observation of nitrous acid in the urban area of Beijing

Maofa Ge , Chaofan Lian , Weigang Wang , Yan Chen , Yusheng Zhang , Jingwei Zhang , Yongchun Liu , Xiaolong Fan , Chang Li , Junlei Zhan , Zhuohui Lin , Chenjie Hua , Wenyu Zhang , Mingyuan Liu , Junling Li , Xuefei Wang , Junling An , Yujing Mu , Jianmin Chen , Min Shao , Zifa Wang


Received June 01, 2021,Revised , Accepted September 03, 2021, Available online February 20, 2022

Volume 34,2022,Pages 334-342

The particulate matter (PM) pollution has been significantly improved by carrying out various valid emission control strategies since 2013 in China. Meanwhile the variation trend of nitrous acid (HONO) is worthy to investigate due to its vital role in the atmospheric oxidation process. In this study, field observation in the winter is conducted to investigate the concentration of HONO in an urban area of Beijing. In the winter of 2019, the mean HONO concentration is 1.38 ppbV during the whole winter. Photo-enhanced NO2 heterogeneous reactions on the ground and aerosol surfaces were found as the possible daytime sources of HONO. Compared to O3, photolysis of HONO dominates the primary OH sources during the winter time. To understand the HONO pollution patterns by years variation, multi-year data is summarized and finds that primary pollutants including CO and NO decreased, but secondary pollutants i.e., HONO (mostly generated via secondary process) increased. Our study highlights the requirement to mitigate secondary pollution by control HONO concentration.

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