Potential Effect of Halogens on Atmospheric Oxidation in China
- 1Department of Atmospheric Chemistry and Climate, Institute of Physical Chemistry Rocasolano, CSIC, Madrid 28006, Spain
- 2Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China
- 3National Exposure Research Laboratory, Environmental Protection Agency, Research Triangle Park, NC 27711, United States
- 4Atmospheric and Oceanic Sciences, Princeton University, Princeton, New Jersey 08540, USA
- 5Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration, Princeton, New Jersey, 08544, United States
- 6Department of Earth System Science, Tsinghua University, Beijing 100084, China
- 7Division of Environment and Sustainability, Hong Kong University of Science and Technology, Hong Kong, China
- 8Department of Environmental Science and Engineering, Fudan University, Shanghai 200433, China
Air pollution has been a hazard in China over recent decades threatening the health of half a billion people. Much effort has been devoted to mitigating air pollution in China leading to a tremendous reduction in primary pollutants emissions from 2013 to 2017, while a continuously worsening trend of surface ozone (O3, a secondary pollutant and greenhouse gas) was observed over the same period. Atmospheric oxidation, dominated by daytime reactions involving hydroxyl radicals (OH), is the critical process to convert freshly-emitted compounds into secondary pollutants, and is underestimated in current models of China’s air pollution. Halogens (chlorine, bromine, and iodine) are known to profoundly influence oxidation chemistry in the marine environment; however, their impact on atmospheric oxidation and air pollution in China is unknown. In the present study, we report for the first time that halogens substantially enhance the total atmospheric oxidation capacity in polluted areas of China, typically 10% to 20% (up to 87% in winter) and mainly by significantly increasing OH level. The enhanced oxidation along the coast is driven by oceanic emissions of bromine and iodine, and that over the inland areas by anthropogenic emission of chlorine. The extent and seasonality of halogen impact are largely explained by the dynamics of Asian monsoon, location and intensity of halogen emissions, and O3 formation regime. The omission of halogen emissions and chemistry may lead to significant errors in historical re-assessments and future projections of the evolution of atmospheric oxidation in polluted regions.
How to cite: Li, Q., Badia, A., Wang, T., Sarwar, G., Fu, X., Zhang, L., Zhang, Q., Fung, J., Cuevas, C. A., Wang, S., Zhou, B., and Saiz-Lopez, A.: Potential Effect of Halogens on Atmospheric Oxidation in China, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3004, https://doi.org/10.5194/egusphere-egu2020-3004, 2020.
