In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 21, No. 14 ( 2021-07-29), p. 11437-11452
Abstract:
Abstract. Gaseous hydrochloric (HCl) and hydrobromic acid (HBr) are vital halogen
species that play essential roles in tropospheric physicochemical processes.
Yet, the 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 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 in urban Beijing, China,
during winter and early spring of 2019. We observed significant HCl and HBr
concentrations ranging from a minimum value at 1 × 108 molecules cm−3 (4 ppt) and 4 × 107 molecules cm−3 (1 ppt) up
to 6 × 109 molecules cm−3 (222 ppt) and 1 × 109 molecules cm−3 (37 ppt), 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), gaseous HCl and HBr are found to be related to
anthropogenic burning aerosols. The gas–particle partitioning may also play
a dominant role in the elevated daytime HCl and HBr. During the daytime, the
reactions of HCl and HBr with OH radicals lead to significant production of
atomic Cl and Br, up to 2 × 104 molecules cm−3 s−1 and 8 × 104 molecules cm−3 s−1,
respectively. The production rate of atomic Br (via HBr + OH) is 2–3 times
higher than that of atomic Cl (via HCl + OH), highlighting the potential
importance of bromine chemistry in the urban area. On polluted days, the
production rates of atomic Cl and Br are faster than those on clean days.
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 halogen chemistry,
which could affect the atmospheric oxidation in China.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-21-11437-2021
DOI:
10.5194/acp-21-11437-2021-supplement
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2021
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
Permalink