Nitrate(NO3-)has been the dominant ion of secondary inorganic aerosols(SIAs)in PM2.5 in North China.Tracking the formation mechanisms and sources of particulate nitrate are vital to mitigate air pollution.In this study,PM2.5 samples in winter(January 2020)and in summer(June 2020)were collected in Jiaozuo,China,and water-soluble ions and(815N,818O)-NO3-were analyzed.The results showed that the increase of NO3-concentrations was the most remarkable with increasing PM2.5 pollution level.818O-NO3-values for winter samples(82.7‰ to 103.9‰)were close to calculated δ18O-HNO3(103‰±0.8‰)values by N2O5 path-way,while δ18O-NO3-values(67.8‰ to 85.7‰)for summer samples were close to calculatedδ18O-HNO3 values(61‰±0.8‰)by OH oxidation pathway,suggesting that PM2.5 nitrate is largely from N2O5 pathway in winter,while is largely from OH pathway in summer.Averaged fractional contributions of PN2O5+H2O were 70％and 39％in winter and summer sampling pe-riods,respectively,those of POH were 30％and 61％,respectively.Higher δ15N-NO3-values for winter samples(3.0‰ to 14.4‰)than those for summer samples(-3.7‰ to 8.6‰)might be due to more contributions from coal combustion in winter.Coal combustion(31％±9％,25％±9％in winter and summer,respectively)and biomass burning(30％±12％,36％±12％in winter and summer,respectively)were the main sources using Bayesian mixing model.These results provided clear evidence of particulate nitrate formation and sources under different PM2.5 levels,and aided in reducing atmospheric nitrate in urban environments.

Yanli Li;Yaping Geng;Xiaomian Hu;Xijie Yin

Institute of Resources and Environment,Henan Polytechnic University,Jiaozuo 454000,China;Third Institute of Oceanography,Ministry of Natural Resources,Xiamen 361000,China

环境科学学报（英文版）

[1]Yanli Li;Yaping Geng;Xiaomian Hu;Xijie Yin-.Seasonal differences in sources and formation processes of PM2.5 nitrate in an urban environment of North China)[J].环境科学学报（英文版）,2022(10):94-104

SIAs,Jiaozuo,PN2O5+H2O,riods

Seasonal,differences,sources,formation,processes,PM2,nitrate,urban,North,China,Nitrate,has,been,dominant,secondary,inorganic,aerosols,Tracking,mechanisms,particulate,are,vital,mitigate,air,pollution,In,this,study,samples,winter,January,summer,June,were,collected,water,soluble,815N,818O,analyzed,results,showed,that,increase,concentrations,was,most,remarkable,increasing,values,close,calculated,HNO3,by,while,oxidation,pathway,suggesting,largely,from,Averaged,fractional,contributions,sampling,respectively,those,POH,Higher,than,might,due,more,coal,combustion,Coal,biomass,burning,main,using,Bayesian,mixing,model,These,provided,clear,evidence,under,different,levels,aided,reducing,atmospheric,environments

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