Atmospheric gaseous hydrochloric and hydrobromic acid in urban Beijing, China: detection, source identification and potential atmospheric impacts
- 1University of Helsinki, Institute for Atmospheric and Earth System Research (INAR), Finland (lei.yao@helsinki.fi)
- 2Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100089, China.
- 3State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
- 4Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China.
- 5Department of Chemistry, University of Helsinki, FI-00014 Helsinki, Finland.
- 6Aerosol Physics Laboratory, Physics Unit, Tampere University, Tampere 33100, Finland
- 7Aerodyne Research Inc., Billerica, Massachusetts 01821, USA.
Gaseous hydrochloric (HCl) and hydrobromic acid (HBr) are vital halogen species that play essential roles in tropospheric physicochemical processes. Yet, majority of the current studies on these halogen species were conducted in marine or coastal areas. Detection and source identification of HCl and HBr in inland urban areas (especially megacities) remain scarce, thus, limiting the full understanding of halogen chemistry and potential atmospheric impacts in the environments with limited influence from the marine sources. Here, both gaseous HCl and HBr were concurrently measured by Chemical Ionization-Atmospheric Pressure interface-Long Time Of Flight-Mass Spectrometer (CI-APi-LTOF-MS) in urban Beijing, China at the BUCT station (39.94° N, 116.30° E) during winter and early spring of 2019. We observed significant HCl and HBr concentrations ranged from a minimum value at 1.3×108 cm-3 and 4.3×107 cm-3 up to 5.9×109 cm-3 and 1.2×109 cm-3, respectively. The HCl and HBr concentrations are enhanced along with the increase of atmospheric temperature, UVB, and levels of gaseous HNO3. Based on the air mass analysis and high correlations of HCl and HBr with the burning indicators (HCN and HCNO), the gaseous HCl and HBr are found to be related to anthropogenic burning aerosols. The gas-aerosol partitioning may also play a dominant role in the elevated daytime HCl and HBr. During the daytime, the reaction of HCl and HBr with OH radicals lead to significant production of atomic Cl and Br, up to 1.7×104 cm-3 s-1and 7.9×104 cm-3 s-1, respectively. The production rate of atomic Br (via HBr + OH) are 2-3 times higher than that of atomic Cl (via HCl + OH), highlighting the potential importance of bromine chemistry in the urban area. Furthermore, our observations of elevated HCl and HBr may suggest an important recycling pathway of halogen species in inland megacities, and may provide a plausible explanation for the widespread of halogen chemistry, which could affect the atmospheric oxidation in China.
How to cite: Yao, L., Fan, X., Cai, J., Yan, C., Chu, B., R. Dällenbach, K., Wang, Y., Dada, L., Zha, Q., Kontkanen, J., Kurtén, T., Iyer, S., T Kujansuu, J., Petäjä, T., Worsnop, D., Kerminen, V.-M., Liu, Y., Bianhi, F., Tham, Y. J., and Kulmala, M.: Atmospheric gaseous hydrochloric and hydrobromic acid in urban Beijing, China: detection, source identification and potential atmospheric impacts, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3482, https://doi.org/10.5194/egusphere-egu21-3482, 2021.
