Nitrous acid in the polluted coastal atmosphere of the South China Sea: Ship emissions, budgets, and impacts

Rongrong Gu; Weihao Wang; Xiang Peng; Men Xia; Min Zhao; Yingnan Zhang; Ya'nan Wang; Yiming Liu; Hengqing Shen; Likun Xue; Tao Wang; Wenxing Wang

doi:10.1016/j.scitotenv.2022.153692

Nitrous acid in the polluted coastal atmosphere of the South China Sea: Ship emissions, budgets, and impacts

Sci Total Environ. 2022 Jun 20:826:153692. doi: 10.1016/j.scitotenv.2022.153692. Epub 2022 Feb 16.

Authors

Rongrong Gu¹, Weihao Wang², Xiang Peng³, Men Xia⁴, Min Zhao⁵, Yingnan Zhang⁵, Ya'nan Wang⁴, Yiming Liu⁶, Hengqing Shen⁵, Likun Xue⁷, Tao Wang⁸, Wenxing Wang⁵

Affiliations

¹ Environment Research Institute, Shandong University, Qingdao 266237, China; Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China.
² Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China; Hangzhou PuYu Technology Development Co., Ltd, Hangzhou 311300, China.
³ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China; Department of Ambient Air Quality Monitoring, China National Environmental Monitoring Center, Beijing 100012, China.
⁴ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China.
⁵ Environment Research Institute, Shandong University, Qingdao 266237, China.
⁶ School of Atmospheric Sciences, Sun Yat-sen University, Zhuhai 519082, China.
⁷ Environment Research Institute, Shandong University, Qingdao 266237, China; Collaborative Innovation Center for Climate Change, Nanjing, Jiangsu 210023, China. Electronic address: xuelikun@sdu.edu.cn.
⁸ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong 999077, China; Environment Research Institute, Shandong University, Qingdao 266237, China. Electronic address: tao.wang@polyu.edu.hk.

PMID: 35182648
DOI: 10.1016/j.scitotenv.2022.153692

Abstract

Nitrous acid (HONO) can significantly contribute to hydroxyl radicals (OH) and thus regulate atmospheric oxidation chemistry; however, ambient HONO sources are not well quantified and vary in different environments. In this study, we conducted comprehensive field observations at a coastal site in the South China Sea and performed chemical box modelling to demonstrate contrasting budgets and impacts of diurnal atmospheric HONO derived from the sea, coastline and continent. The ship emission ratio of HONO/nitrogen oxides (NO_x) (1.21 ± 0.99%) was calculated from hundreds of night-time fresh plume measurements. Offshore marine air was frequently influenced by ship exhausts, and the sea acted as an HONO sink. Heterogeneous conversions of nitrogen dioxide (NO₂) on underlying surfaces and photolysis of adsorbed nitric acid (HNO_3(ads)) were the major HONO sources in coastal air, when heterogeneous NO₂ conversions on the ground surface and the homogeneous NO + OH reaction dominated HONO formation in continental air. HONO photolysis was a significant source of reactive radicals (RO_x = OH + HO₂ + RO₂) in these air masses. Atmospheric box model including only homogeneous HONO source of the NO + OH reactions significantly underpredicted the OH concentration and atmospheric oxidising capacity in coastal and continental air. This study provides new insights into the complex sources and significant impacts of HONO in the polluted coastal boundary layer.

Keywords: Atmospheric oxidising capacity; Budget analysis; Coastal boundary layer; Nitrous acid (HONO); Ship emission.

MeSH terms

Atmosphere
China
Nitrogen Dioxide*
Nitrous Acid* / analysis
Ships

Substances

Nitrogen Dioxide
Nitrous Acid