Chemical Characteristics Of PM_2.5 And Water-Soluble Organic Nitrogen In Yangzhou,China

Chemical characterization of the fine atmospheric particles(PM_2.5)is important for effective reduction of air pollution.This work analyzed PM_2.5 samples in Yangzhou,China,by using a suite of techniques.Ionic species,organic matter?OM?,elemental carbon?EC?and trace metals were determined,and particularly,an Aerodyne soot-particle aerosol mass spectrometer?SP-AMS?was introduced to determine the OM mass rather than only organic carbon mass.We found that inorganic ionic species was dominant?⁵2%?,organics occupied about 1/4,while trace metals?¹%?and elemental carbon contributed insignificantly?².1%?to the total PM_2.5mass.Water-soluble OM appeared to link closely with secondary OM,while water-insoluble OM correlated well with primary OM.The PM_2.5 concentrations were relatively low during summertime while its compositions varied little among different months.Seasonal variations of water-soluble organic nitrogen?WSON?concentrations were not significant,while the mass contributions of WSON to total nitrogen were remarkably high during summer and autumn.The WSON was found to associate better with secondary source based on both correlation analyses and principle component analyses.Analyses of potential source contributions to WSON showed that regional emission was dominant during autumn and winter,while ocean became relatively important during spring and summer.