Concentration and sources of atmospheric nitrous acid (HONO) at an urban site in Western China.
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 NO2are very similar and positively correlated which, together with the similar diurnal profiles of HONO/NO2ratio 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-1is required to explain the observed HONO concentration, which contributes 60.8% of the observed daytime HONO.
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.
Ru-Jin
RJ
Huang
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.
Lu
L
Yang
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.
Junji
J
Cao
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.
Qiyuan
Q
Wang
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.
Xuexi
X
Tie
The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong, China.
Kin-Fai
KF
Ho
Department of Environmental Sciences and Engineering, Xi'an Jiaotong University, Xi'an, 710049, China.
Zhenxing
Z
Shen
RCE-TEA, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China.
Renjian
R
Zhang
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.
Guohui
G
Li
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.
Chongshu
C
Zhu
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.
Ningning
N
Zhang
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.
Wenting
W
Dai
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.
Jiamao
J
Zhou
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.
Suixin
S
Liu
Key Laboratory of Reservoir Aquatic Environment of CAS, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China.
Yang
Y
Chen
School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
Jun
J
Chen
School of Physics and Centre for Climate and Air Pollution Studies, National University of Ireland Galway, Galway, Ireland.
Colin D
CD
O'Dowd
HONO source and formation; Heterogeneous conversion; Nitrogen oxides; Nitrous acid