10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Size-segregated Chemical Components of Aerosol Particles in Hefei, China
ANNA LI, Laboratory of Atmospheric Physico-Chemistry, Anhui Institute
Abstract Number: 78 Working Group: Aerosol Chemistry
Abstract To investigate the characteristics of aerosols in typical pollution episodes, water-soluble inorganic ions,including anions (NO3−,SO42−,F−,Cl−) and cations (NH4+,Na+,Ca2+,Mg2+,K+) in 8 size-segregated particle fractions, are collected by an Anderson sampler from Dec.2016 to Jan.2017 in Hefei. The results of chemical composition analysis showed that secondary water soluble ions NO3−,SO42−,NH4+ (SWSI) composed more than half the total ions, and are mainly found in fine particles (aerodynamic diameters less than 2.1 mm), while Ca2+ and Mg2+ contributed to a large fraction of the total water-soluble ions in coarse particles (aerodynamic diameters greater than 2.1 mm and less than 9.0 mm). The SWSI showed a bimodal size distribution with the peak mass concentration of particles shifted from 0.43–0.65 μm on clear days to 0.65–1.1 μm on lightly polluted days and to 1.1–2.1 μm on heavily polluted days. NH4+ played an important role in the size distributions and the formations of NO3−,SO42−. Heterogeneous reaction is the main formation mechanism of NO3− and SO42−, which tended to be enriched in the coarse mode of aerosol. In this study the average NO3−/ SO42− mass ratios decreased from clear (3.7 and 3.8, respectively) to LP (3 and 3.6, respectively) and to HP (2.6 and 2.9, respectively) days for both fine and coarse particles. The mass ratio suggesting that Local sources played a more important role in the formation of particles .Meteorological conditions contributed to influence the secondary formation and regulate the size distributions of SWSI. Short-distance transport, low wind speed and high RH were highly responsible for the formation of the pollution event.