Size distributions of water-soluble inorganic ions of atmospheric aerosol particles in autumn in Jinan

Aerosol samples were collected in urban Jinan during October 2009 by a 8-stage Micro-Orifice Uniform Deposit Impactor.To characterize mass size distributions of water-soluble inorganic ions of atmospheric aerosol particles,the ions were analyzed by ion chromatography.SO42-,NO3-,NH4+,and Ca2+ were the most abundant ions which accounted for 92% of the total water-soluble ions.The concentrations of SO42-,NO3-,NH4+,K+,and Cl-showed a sharp change,which was influenced mainly by wind speed and direction.The size distributions of SO42-and NH4+ were single-modal,and the major fraction was present in the fine mode.The peaks in SO42-and NH4+ shifted from 0.32-0.56 μm to 1-1.8 μm when their mass concentration increased.The size distributions of NO3-were bi-modal.Its peak in the fine-mode shifted from 0.56-1 μm to 1-1.8 μm when the mass concentration increased.The NO3-peak in coarse-mode was at 3.2-5.6 μm.In addition,our study results show that NH4+ could completely neutralize SO42-and NO3-in fine particles,as(NH4)2SO4 and NH4NO3 aerosol particles.