Photodissociation of particulate nitrate as a source of daytime tropospheric Cl2

Xiang Peng; Tao Wang; Weihao Wang; A. R. Ravishankara; Christian George; Men Xia; Min Cai; Qinyi Li; Christian Mark Salvador; Chiho Lau; Xiaopu Lyu; Chun Nan Poon; Abdelwahid Mellouki; Yujing Mu; Mattias Hallquist; Alfonso Saiz-Lopez; Hai Guo; Hartmut Herrmann; Chuan Yu; Jianing Dai; Yanan Wang; Xinke Wang; Alfred Yu; Kenneth Leung; Shuncheng Lee; Jianmin Chen

doi:10.1038/s41467-022-28383-9

Photodissociation of particulate nitrate as a source of daytime tropospheric Cl₂

Xiang Peng, Tao Wang, Weihao Wang, A. R. Ravishankara, Christian George, Men Xia, Min Cai, Qinyi Li, Christian Mark Salvador, Chiho Lau, Xiaopu Lyu, Chun Nan Poon, Abdelwahid Mellouki, Yujing Mu, Mattias Hallquist, Alfonso Saiz-Lopez, Hai Guo, Hartmut Herrmann, Chuan Yu, Jianing DaiYanan Wang, Xinke Wang, Alfred Yu, Kenneth Leung, Shuncheng Lee, Jianmin Chen

Research output: Contribution to journal › Article › peer-review

36 Scopus citations

Abstract

Chlorine atoms (Cl) are highly reactive and can strongly influence the abundances of climate and air quality-relevant trace gases. Despite extensive research on molecular chlorine (Cl₂), a Cl precursor, in the polar atmosphere, its sources in other regions are still poorly understood. Here we report the daytime Cl₂ concentrations of up to 1 ppbv observed in a coastal area of Hong Kong, revealing a large daytime source of Cl₂ (2.7 pptv s⁻¹ at noon). Field and laboratory experiments indicate that photodissociation of particulate nitrate by sunlight under acidic conditions (pH < 3.0) can activate chloride and account for the observed daytime Cl₂ production. The high Cl₂ concentrations significantly increased atmospheric oxidation. Given the ubiquitous existence of chloride, nitrate, and acidic aerosols, we propose that nitrate photolysis is a significant daytime chlorine source globally. This so far unaccounted for source of chlorine can have substantial impacts on atmospheric chemistry.

Original language	English
Article number	939
Journal	Nature Communications
Volume	13
Issue number	1
DOIs	https://doi.org/10.1038/s41467-022-28383-9
State	Published - Dec 2022
Externally published	Yes

Funding

We thank the Hong Kong Environmental Protection Department for providing space at its supersite for our field measurements and for the provision of some VOCs and aerosol composition data. We thank Chung Hon Larry Suen for the help in the field measurements. We thank Bobo Wang, W.S. Lam, Yanlin Zhang, and Prof. Wei Chu for their help in the laboratory experiments. This research is supported by the Hong Kong Research Grants Council (T24-504/17-N and A-PolyU502/16 to T.W.), the Agence Nationale de la Recherche (ANR-16-CE01-0013 to C.G.), the Swedish Research Council (2013-6917 to M.H. and C.M.S), and the European Research Council Executive Agency under the European Union s Horizon 2020 Research and Innovation programme (Project ‘ERC-2016-COG726349 CLIMAHAL’ to Q.L. and A.S-L.). We thank the Hong Kong Environmental Protection Department for providing space at its supersite for our field measurements and for the provision of some VOCs and aerosol composition data. We thank Chung Hon Larry Suen for the help in the field measurements. We thank Bobo Wang, W.S. Lam, Yanlin Zhang, and Prof. Wei Chu for their help in the laboratory experiments. This research is supported by the Hong Kong Research Grants Council (T24-504/17-N and A-PolyU502/16 to T.W.), the Agence Nationale de la Recherche (ANR-16-CE01-0013 to C.G.), the Swedish Research Council (2013-6917 to M.H. and C.M.S), and the European Research Council Executive Agency under the European Union s Horizon 2020 Research and Innovation programme (Project ‘ERC-2016-COG726349 CLIMAHAL’ to Q.L. and A.S-L.).

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Peng, X., Wang, T., Wang, W., Ravishankara, A. R., George, C., Xia, M., Cai, M., Li, Q., Salvador, C. M., Lau, C., Lyu, X., Poon, C. N., Mellouki, A., Mu, Y., Hallquist, M., Saiz-Lopez, A., Guo, H., Herrmann, H., Yu, C., ... Chen, J. (2022). Photodissociation of particulate nitrate as a source of daytime tropospheric Cl₂. Nature Communications, 13(1), Article 939. https://doi.org/10.1038/s41467-022-28383-9

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title = "Photodissociation of particulate nitrate as a source of daytime tropospheric Cl2",

abstract = "Chlorine atoms (Cl) are highly reactive and can strongly influence the abundances of climate and air quality-relevant trace gases. Despite extensive research on molecular chlorine (Cl2), a Cl precursor, in the polar atmosphere, its sources in other regions are still poorly understood. Here we report the daytime Cl2 concentrations of up to 1 ppbv observed in a coastal area of Hong Kong, revealing a large daytime source of Cl2 (2.7 pptv s−1 at noon). Field and laboratory experiments indicate that photodissociation of particulate nitrate by sunlight under acidic conditions (pH < 3.0) can activate chloride and account for the observed daytime Cl2 production. The high Cl2 concentrations significantly increased atmospheric oxidation. Given the ubiquitous existence of chloride, nitrate, and acidic aerosols, we propose that nitrate photolysis is a significant daytime chlorine source globally. This so far unaccounted for source of chlorine can have substantial impacts on atmospheric chemistry.",

author = "Xiang Peng and Tao Wang and Weihao Wang and Ravishankara, {A. R.} and Christian George and Men Xia and Min Cai and Qinyi Li and Salvador, {Christian Mark} and Chiho Lau and Xiaopu Lyu and Poon, {Chun Nan} and Abdelwahid Mellouki and Yujing Mu and Mattias Hallquist and Alfonso Saiz-Lopez and Hai Guo and Hartmut Herrmann and Chuan Yu and Jianing Dai and Yanan Wang and Xinke Wang and Alfred Yu and Kenneth Leung and Shuncheng Lee and Jianmin Chen",

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year = "2022",

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doi = "10.1038/s41467-022-28383-9",

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Peng, X, Wang, T, Wang, W, Ravishankara, AR, George, C, Xia, M, Cai, M, Li, Q, Salvador, CM, Lau, C, Lyu, X, Poon, CN, Mellouki, A, Mu, Y, Hallquist, M, Saiz-Lopez, A, Guo, H, Herrmann, H, Yu, C, Dai, J, Wang, Y, Wang, X, Yu, A, Leung, K, Lee, S & Chen, J 2022, 'Photodissociation of particulate nitrate as a source of daytime tropospheric Cl₂', Nature Communications, vol. 13, no. 1, 939. https://doi.org/10.1038/s41467-022-28383-9

TY - JOUR

T1 - Photodissociation of particulate nitrate as a source of daytime tropospheric Cl2

AU - Peng, Xiang

AU - Wang, Tao

AU - Wang, Weihao

AU - Ravishankara, A. R.

AU - George, Christian

AU - Xia, Men

AU - Cai, Min

AU - Li, Qinyi

AU - Salvador, Christian Mark

AU - Lau, Chiho

AU - Lyu, Xiaopu

AU - Poon, Chun Nan

AU - Mellouki, Abdelwahid

AU - Mu, Yujing

AU - Hallquist, Mattias

AU - Saiz-Lopez, Alfonso

AU - Guo, Hai

AU - Herrmann, Hartmut

AU - Yu, Chuan

AU - Dai, Jianing

AU - Wang, Yanan

AU - Wang, Xinke

AU - Yu, Alfred

AU - Leung, Kenneth

AU - Lee, Shuncheng

AU - Chen, Jianmin

PY - 2022/12

Y1 - 2022/12

N2 - Chlorine atoms (Cl) are highly reactive and can strongly influence the abundances of climate and air quality-relevant trace gases. Despite extensive research on molecular chlorine (Cl2), a Cl precursor, in the polar atmosphere, its sources in other regions are still poorly understood. Here we report the daytime Cl2 concentrations of up to 1 ppbv observed in a coastal area of Hong Kong, revealing a large daytime source of Cl2 (2.7 pptv s−1 at noon). Field and laboratory experiments indicate that photodissociation of particulate nitrate by sunlight under acidic conditions (pH < 3.0) can activate chloride and account for the observed daytime Cl2 production. The high Cl2 concentrations significantly increased atmospheric oxidation. Given the ubiquitous existence of chloride, nitrate, and acidic aerosols, we propose that nitrate photolysis is a significant daytime chlorine source globally. This so far unaccounted for source of chlorine can have substantial impacts on atmospheric chemistry.

AB - Chlorine atoms (Cl) are highly reactive and can strongly influence the abundances of climate and air quality-relevant trace gases. Despite extensive research on molecular chlorine (Cl2), a Cl precursor, in the polar atmosphere, its sources in other regions are still poorly understood. Here we report the daytime Cl2 concentrations of up to 1 ppbv observed in a coastal area of Hong Kong, revealing a large daytime source of Cl2 (2.7 pptv s−1 at noon). Field and laboratory experiments indicate that photodissociation of particulate nitrate by sunlight under acidic conditions (pH < 3.0) can activate chloride and account for the observed daytime Cl2 production. The high Cl2 concentrations significantly increased atmospheric oxidation. Given the ubiquitous existence of chloride, nitrate, and acidic aerosols, we propose that nitrate photolysis is a significant daytime chlorine source globally. This so far unaccounted for source of chlorine can have substantial impacts on atmospheric chemistry.

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AN - SCOPUS:85124777084

SN - 2041-1723

VL - 13

JO - Nature Communications

JF - Nature Communications

IS - 1

M1 - 939

ER -

Photodissociation of particulate nitrate as a source of daytime tropospheric Cl₂

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