Concentration and sources of atmospheric nitrous acid (HONO) at an urban site in Western China

Ru-Jin Huang; Lu Yang; Junji Cao; Qiyuan Wang; Xuexi Tie; Kin-Fai Ho; Zhenxing Shen; Renjian Zhang; Guohui Li; Chongshu Zhu; Ningning Zhang; Wenting Dai; Jiamao Zhou; Suixin Liu; Yang Chen; Jun Chen; Colin D O'Dowd

doi:10.1016/j.scitotenv.2017.02.166

Concentration and sources of atmospheric nitrous acid (HONO) at an urban site in Western China

Sci Total Environ. 2017 Sep 1:593-594:165-172. doi: 10.1016/j.scitotenv.2017.02.166. Epub 2017 Mar 23.

Authors

Ru-Jin Huang¹, Lu Yang², Junji Cao², Qiyuan Wang², Xuexi Tie³, Kin-Fai Ho⁴, Zhenxing Shen⁵, Renjian Zhang⁶, Guohui Li², Chongshu Zhu², Ningning Zhang², Wenting Dai², Jiamao Zhou², Suixin Liu², Yang Chen⁷, Jun Chen⁸, Colin D O'Dowd⁹

Affiliations

¹ Key Laboratory of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth and Environment, Chinese Academy of Sciences, Xi'an 710061, China; School of Physics and Centre for Climate and Air Pollution Studies, National University of Ireland Galway, Galway, Ireland; Centre for Atmospheric and Marine Sciences, Xiamen Huaxia University, Xiamen 361024, China. Electronic address: rujin.huang@ieecas.cn.
² Key Laboratory of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth and Environment, Chinese Academy of Sciences, Xi'an 710061, China.
³ Key Laboratory of Aerosol Chemistry and Physics, State Key Laboratory of Loess and Quaternary Geology, Institute of Earth and Environment, Chinese Academy of Sciences, Xi'an 710061, China; Shanghai Key Laboratory of Meteorology and Health, Shanghai 200030, China. Electronic address: tiexx@ieecas.cn.
⁴ The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China.
⁵ Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an, 710049, China.
⁶ RCE-TEA, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
⁷ Key Laboratory of Reservoir Aquatic Environment of CAS, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China.
⁸ School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
⁹ School of Physics and Centre for Climate and Air Pollution Studies, National University of Ireland Galway, Galway, Ireland.

PMID: 28343037
DOI: 10.1016/j.scitotenv.2017.02.166

Abstract

Highly time-resolved measurements of nitrous acid (HONO) were carried out with a highly sensitive long path absorption photometer (LOPAP) at an urban site of Xi'an in Western China from 24 July to 6 August 2015 to investigate the atmospheric variations, sources, and formation pathways of HONO. The concentrations of HONO vary from 0.02 to 4.3ppbv with an average of 1.12ppbv for the entire measurement period. The variation trends of HONO and NO₂ are very similar and positively correlated which, together with the similar diurnal profiles of HONO/NO₂ ratio and HONO, suggest the importance of heterogeneous conversion of HONO from NO₂. The nocturnal HONO level is governed by heterogeneous formation from NO₂, followed by homogeneous formation of NO with OH and then by direct emissions. Further, it is found that the heterogeneous formation of HONO is largely affected by relative humidity and aerosol surface. Daytime HONO budget analysis indicates that an additional unknown source with HONO production rate of 0.75ppbvh^-1 is required to explain the observed HONO concentration, which contributes 60.8% of the observed daytime HONO.

Keywords: HONO source and formation; Heterogeneous conversion; Nitrogen oxides; Nitrous acid.