Light scattering extinction characterization of particulates and chemical composition contribution in Tianjin

To know the aerosol optical characterization and scattering extinction contribution of chemistry composition, an online observation work of light scattering coefficient was made, PM 2.5 sampling was also made on January, April, July and October which was taken as typical 4months of its seasons. The light scattering coefficient was higher in autumn and winter than in spring and summer. A relation analysis showed that the mass scattering coefficient of PM 2.5 in winter was 5.18 m 2/g, which was the highest of the whole year. Transportation and dissolution were obvious when the wind speed was above 3 m/s; RH played an important increase role on light scattering coefficient when it was high enough. OC and sulfate in PM 2.5 might be the main composition that affected the light scattering coefficient by the multi linear regression analysis. Based on the method of IMPROVE to calculate the contribution of chemical composition, organics contributed 38.51% of the total scattering coefficient, which was of the highest.