Heavy haze events have become a serious environment and health problem in China and many devel-oping countries,especially in big cities,like Beijing.However,the factors and processes triggered the formation of secondary particles from the gaseous pollutants are still not clear,and the processes driving evolution and degradation of heavy haze events are not well understood.Iodine isotopes(127I and 129I)as tracers were analyzed in time series aerosol samples collected from Beijing.It was observed that the 127I concentrations in aerosols peaked during the heavy haze events.The conversion of gaseous iodine to particular iodine oxides through photochemical reactions provides primary nuclei in nucleation and formation of secondary air particles,which was strengthened as the external iodine input from the fossil fuel burning in the south/southeast industrial cities and consequentially induced heavy haze events.An-thropogenic 129I concentrations peaked during clean air conditions and showed high levels in spring and later autumn compared to that in summer.129I originated from the direct air discharges and re-emissions from contaminated seawaters by the European nuclear fuel reprocessing plants was transported to Beijing by the interaction of Westerlies and East Asian winter monsoon.Three types of mechanisms were found in the formation and evolution of heavy haze events in Beijing by the variation of 127I and 129I,i.e.,iodine oxides intermediated secondary air particles,dust storm and mixed mode by both secondary air particles and dust storm induced processes.

Miao Fang;Xue Zhao;Yixuan Liu;Yang Shao;Ning Chen;Min Luo;Luyuan Zhang;Qi Liu;Lingling Ma;Diandou Xu;Xiaolin Hou

State Key Laboratory of Loess and Quaternary Geology,Shaanxi Key Laboratory of Accelerator Mass Spectrometry Technology and Application,Xi'an AMS Center,Institute of Earth Environment,Chinese Academy of Sciences,Xi'an 710061,China;University of Chinese Academy of Sciences,Beijing 100049,China;Xi'an Institute for Innovative Earth Environment Research, Xi'an 710061,China;Open Studio for Oceanic-Continental Climate and Environment Changes,Pilot National Laboratory for Marine Science and Technology(Qingdao),Qiangdao 266061,China;Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;CAS Center for Excellence in Quaternary Science and Global Change,Xi'an 710061,China;Open Studio for Oceanic-Continental Climate and Environment Changes, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qiangdao 266061, China;Department of Environmental Engineering,Technical University of Denmark,Ris? Campus,Roskilde 4000,Denmark

中国化学快报（英文版）

[1]Miao Fang;Xue Zhao;Yixuan Liu;Yang Shao;Ning Chen;Min Luo;Luyuan Zhang;Qi Liu;Lingling Ma;Diandou Xu;Xiaolin Hou-.Occurrence,evolution and degradation of heavy haze events in Beijing traced by iodine-127 and iodine-129 in aerosols)[J].中国化学快报（英文版）,2022(07):3507-3515

consequentially,thropogenic,Westerlies

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