Depending on various government policies,COVID-19(Corona Virus Disease-19)lockdowns have had diverse impacts on global aerosol concentrations.In 2022,Changchun,a provincial capital city in Northeast China,suffered a severe COVID-19 outbreak and implemented a very strict lockdown that lasted for nearly two months.Using ground-based polarization Light Detection and Ran-ging(LiDAR),we detected real-time aerosol profile parameters(EC,extinction coefficient;DR,depolarization ratio;AOD,aerosol op-tical depth),as well as air-quality and meteorological indexes from 1 March to 30 April in 2021 and 2022 to quantify the effects of lock-down on aerosol concentrations.The period in 2022 was divided into three stages:pre-lockdown(1-10 March),strict lockdown(11 March to 10 April),and partial lockdown(11-30 April).The results showed that,during the strict lockdown period,compared with the pre-lockdown period,there were substantial reductions in aerosol parameters(EC and AOD),and this was consistent with the concentra-tions of the atmospheric pollutants PM2.5(particulate matter with an aerodynamic diameter＜2.5 pm)and PM10(particulate matter with an aerodynamic diameter＜10 pm),and the 03 concentration increased by 8.3％.During the strict lockdown,the values of EC within 0-1 km and AOD decreased by 16.0％and 11.2％,respectively,as compared to the corresponding period in 2021.Lockdown reduced the conventional and organized emissions of air pollutants,and it clearly delayed the time of seasonal emissions from agricultural burn-ing;however,it did not decrease the number of farmland fire points.Considering meteorological factors and eliminating the influence of wind-blown dust events,the results showed that reductions from conventional organized emission sources during the strict lockdown contributed to a 30％air-quality improvement and a 22％reduction in near-surface extinction(0-2 km).Aerosols produced by urban epidemic prevention and disinfection can also be identified using the EC.Regarding seasonal sources of agricultural straw burning,the concentrated burning induced by the epidemic led to the occurrence of heavy pollution from increased amounts of atmospheric aerosols,with a contribution rate of 62％.These results indicate that there is great potential to further improve air quality in the local area,and suggest that the comprehensive use of straw accompanied by reasonable planned burning is the best way to achieve this.

CHEN Weiwei;DUANMU Lingjian;QIN Yang;YANG Hongwu;FU Jing;LU Chengwei;FENG Wei;GUO Li

Key Laboratory of Wetland Ecology and Environment,Northeast Institute of Geography and Agroecology,Chinese Academy of Sci-ences,Changchun 130102,China;College of Biological and Agricultural Engineering,Jilin University,Changchun 130022,China;Jilin Provincial Ecological Environment Monitoring Center,Changchun 130012,China;Hongke Photonics Company,Liaoyuan 136200,China;The Department of Ophthalmology,The First Hospital of Jilin University,Changchun 130021,China;Key Lab of Groundwater Resources and Environment,Jilin University,Changchun 130021,China

中国地理科学（英文版）

[1]CHEN Weiwei;DUANMU Lingjian;QIN Yang;YANG Hongwu;FU Jing;LU Chengwei;FENG Wei;GUO Li-.Lockdown-induced Urban Aerosol Change over Changchun,China During COVID-19 Outbreak with Polarization LiDAR)[J].中国地理科学（英文版）,2022(05):824-833

Lockdown,induced,Urban,Change,Changchun,China,During,Outbreak,Polarization,LiDAR,Depending,various,government,policies,Corona,Virus,Disease,lockdowns,have,had,diverse,impacts,global,concentrations,In,provincial,capital,city,Northeast,suffered,severe,outbreak,implemented,very,strict,that,lasted,nearly,two,months,Using,ground,Light,Detection,Ran,ging,detected,real,profile,parameters,EC,extinction,coefficient,DR,depolarization,AOD,op,tical,depth,well,air,quality,meteorological,indexes,from,March,April,quantify,effects,period,was,divided,into,three,stages,partial,results,showed,during,compared,there,were,substantial,reductions,this,consistent,atmospheric,pollutants,PM2,particulate,matter,aerodynamic,diameter,pm,PM10,increased,by,values,within,decreased,respectively,corresponding,reduced,conventional,organized,emissions,clearly,delayed,seasonal,agricultural,however,did,not,number,farmland,fire,points,Considering,factors,eliminating,influence,wind,blown,dust,events,sources,contributed,improvement,surface,Aerosols,produced,urban,epidemic,prevention,disinfection,can,also,identified,using,Regarding,straw,burning,concentrated,led,occurrence,heavy,pollution,amounts,aerosols,contribution,These,indicate,great,potential,further,local,area,suggest,comprehensive,use,accompanied,reasonable,planned,best,way,achieve

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