Impact of PM2.5 chemical compositions on aerosol light scattering in Guangzhou - the largest megacity in South China

To determine the relationship between bsp and the chemical components of PM2.5, bsp was reconstructed in each season using the original IMPROVE formula with a modification of including sea salt aerosols. The estimated bsp using this method was 22 ± 28% smaller on annual average compared to the measurements. Multiple linear regression of measured bsp against (NH4)2SO4, NH4NO3, OM (Organic Mass), SS (Sea Salt), FS (Fine Soil), and CM (Coarse Mass) were also performed in all the four seasons. The estimated bsp from using the regression equation was 4 ± 12% larger than the measured values. On average, (NH4)2SO4, NH4NO3, OM, SS, FS and CM accounted for 50 ± 11%, 18 ± 10%, 19 ± 5%, 5 ± 4%, 3 ± 2% and 5 ± 6%, respectively, of the estimated bsp.