基于高分辨率在线气溶胶监测仪数据分析南京北郊冬季PM2.5中水溶性离子污染特性

摘要

于2017年1月~2月在南京北郊利用MARGA在线监测仪采集大气细颗粒物(PM2.5)测量气溶胶中的无机离子质量浓度,分析各离子的变化特征及来源.研究表明,南京北郊冬季总水溶性无机离子质量浓度平均值为(48.47 ± 25.44) μg/m3,8种无机离子质量浓度高低顺序为SO2-4 >NO-3>NH+4>Cl- >(K+、Ca2+) >Na+>Mg2+,其中二次无机离子(NH+4、NO-3和SO2-4 )是最主要的水溶性离子.各水溶性无机离子的日变化特征存在差异,其中SO2-4和Cl-的日变化较为显著,变化特征为日间高夜间低.NH+4、NO-3和SO2-4三者在大气中的结合方式为(NH4)2SO4和NH4NO3,主成分分析结果显示,南京北郊冬季大气的污染物来源主要为化石燃料燃烧,另外生物质燃烧和二次转化、矿物粉尘对大气污染也有贡献.%The composition of PM2.5was on-line monitored using MARGA ADI 2080 at northern Nanjing from January 16 to February 16,2017 continuously, in order to analyze the characteristics and source of water-soluble ions. The average of mass concentration of TWSIIs was(48.47 ± 25.44)μg/m3,and the order of concentration of ions was SO2-4 >NO-3>NH+4>Cl- >(K+,Ca2+) >Na+>Mg2+, NH+4、NO-3and SO2-4 were the major compo-nents of water-soluble ions,and the form of existence in the atmosphere were(NH4)2SO4and NH4NO3. The daily variation of SO2-4 and Cl- was significant,characterized by higher at daytime and lower at nighttime. NH+4、NO-3 and SO2-4 existed in the atmosphere in the form of(NH4)2SO4and NH4NO3. The results of principal component analysis showed fossil fuel combustion was the main source of water-soluble ions in PM2.5of northern Nanjing,and biomass burning,secondary formation and dust were also the contributors to the water-soluble ions in PM2.5.