An unexpected large continental source of reactive bromine and chlorine with significant impact on wintertime air quality

Xiang Peng; Weihao Wang; Men Xia; Hui Chen; A R Ravishankara; Qinyi Li; Alfonso Saiz-Lopez; Pengfei Liu; Fei Zhang; Chenglong Zhang; Likun Xue; Xinfeng Wang; Christian George; Jinhe Wang; Yujing Mu; Jianmin Chen; Tao Wang

doi:10.1093/nsr/nwaa304

An unexpected large continental source of reactive bromine and chlorine with significant impact on wintertime air quality

Natl Sci Rev. 2020 Dec 28;8(7):nwaa304. doi: 10.1093/nsr/nwaa304. eCollection 2021 Jul.

Authors

Xiang Peng¹, Weihao Wang¹, Men Xia¹, Hui Chen², A R Ravishankara³, Qinyi Li⁴, Alfonso Saiz-Lopez⁴, Pengfei Liu⁵, Fei Zhang², Chenglong Zhang⁵, Likun Xue⁶, Xinfeng Wang⁶, Christian George⁷, Jinhe Wang⁸, Yujing Mu⁵, Jianmin Chen², Tao Wang¹

Affiliations

¹ Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hong Kong 999077, China.
² Department of Environmental Science and Engineering and Institute of Atmospheric Sciences, Fudan University, Shanghai 200433, China.
³ Departments of Atmospheric Science and Chemistry, Colorado State University, Fort Collins, CO 80523, USA.
⁴ Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid 28006, Spain.
⁵ Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
⁶ Environment Research Institute, Shandong University, Qingdao 266237, China.
⁷ Univ Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, Villeurbanne 69626, France.
⁸ School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan 250101, China.

Abstract

Halogen atoms affect the budget of ozone and the fate of pollutants such as hydrocarbons and mercury. Yet their sources and significances in polluted continental regions are poorly understood. Here we report the observation of unprecedented levels (averaging at 60 parts per trillion) of bromine chloride (BrCl) at a mid-latitude site in North China during winter. Widespread coal burning in rural households and a photo-assisted process were the primary source of BrCl and other bromine gases. BrCl contributed about 55% of both bromine and chlorine atoms. The halogen atoms increased the abundance of 'conventional' tropospheric oxidants (OH, HO₂ and RO₂) by 26%-73%, and enhanced oxidation of hydrocarbon by nearly a factor of two and the net ozone production by 55%. Our study reveals the significant role of reactive halogen in winter atmospheric chemistry and the deterioration of air quality in continental regions where uncontrolled coal combustion is prevalent.

Keywords: BrCl; North China; air pollution; coal burning; oxidation; reactive halogen.