Source Apportionment And Regional Transport Of Anthropogenic Secondary Organic Aerosol During Winter Pollution Periods In The Yangtze River Delta,China

Since the concentrations of primary particles and secondary inorganic aerosol components in China have been reduced significantly due to stringent emission controls,the pollution of secondary organic particulate matter(SOA)remains high.Studies have found that SOA is generally under-predicted by model application due to incomplete SOA formation mechanism,under-predicted volatile species emission and missing SOA precursors,and few studies have been conducted in recent years to determine the source apportionment of SOA in China.In this study,the Community Multiscale Air Quality(CMAQ)model coupled with the updated SAPRC-11 photochemical mechanism and a revised SOA module was applied to investigate the emission sector and regional contributions to SOA in winter 2015(January 5-26,2015)and 2016(December 20,2015-January 20,2016)in the Yangtze River Delta(YRD).The model is generally capable of reproducing the observed SOA concentrations at the Qingpu Supersite in Shanghai.High SOA concentrations in the wintertime of YRD are mainly due to aromatic compounds and dicarbonyls(glyoxal and methylglyoxal),which,on average,account for 43% and 53% of total SOA,respectively.The main contributions by sector in Shanghai,Nanjing and Hangzhou are from Industry,with an average contribution of more than 60%.During heavy pollution episodes,the contributions can reach more than 65%.Regional results of Nanjing and Hangzhou city showed that Jiangsu,Anhui,Shandong,Zhejiang and Henan provinces are the largest five contributions with contributions more than 70%.During the heavy pollution episode of2016 winter,the contributions of local emissions in Zhejiang province was even higher(41%).Other than the industry emissions from each province,the residential from Jiangsu province can also contribute a lot.This study is expected to further clarify the main formation pathway of secondary organic aerosol in urban areas of China.The results of relevant source analysis will help the government develop scientific,accurate and effective SOA pollution control measures,especially emergency control for heavy pollution processes.