Characteristics of Aerosol Ionic Compositions in Summer 2003 at Lin'an of Yangtze Delta Region

With the size-resolved aerosol mass and ion composition data obtained at Lin'an regional atmospheric pollution monitoring station in July 2003, the size distributions of aerosol mass and ionic components, and the correlations between major ion pairs were analyzed. The primary results indicate that in the period of insitu measurement, the aerosols are mainly composed of ne particles. The mass of aerosols with size less than 2.1 μm accounts for 66% of the total mass of all size ranges, in which about 50% of the mass is contributed by the particles with size less than 0.65 μm. Similar to the size distributions of aerosol mass, the water-soluble ions are mainly concentrated in the size range of <0.65 μm, accounting for about 77% of the sum of analyzed ions, and the ions within the range of <2.1 μm reach 88%. The sulfate, ammonium, and potassium are the dominant ionic components in ne particles (particle size less than 2.1 μm). Ion correlation analysis suggests that the sulfates in ne particles are mostly in the compounds of (NH4)2SO4, Na2SO4, and K2SO4, but for submicron particles the sulfates are mainly in the form of (NH4)2SO4.