[Source Apportionment and Optical Properties of Fine Particles Associated with Regional Pollution in the Yangtze...

In order to study the distribution and optical characteristics of fine particulate matter pollution in the Yangtze River Delta, PM_2.5 samples were collected and analyzed from city (Suzhou), suburb (Nanjing), and regional background monitoring stations (Lin'an). The average concentrations of PM_2.5 in Suzhou, Nanjing, and Lin'an were (169.8±56.5), (169.9±51.2), and (154.0±54.9) μg·m^-3, respectively. There was little difference in meteorological conditions and the chemical composition of PM_2.5 among the three sites, and PM_2.5 pollution showed significant synchronization and regionalization characteristics. The extinction coefficients estimated using a chemical component method for Suzhou, Nanjing, and Lin'an are (561±223), (655±340), and (679±349) Mm^-1, respectively. There is strong correlation between the extinction coefficients estimated by the chemical component method and those estimated by a visibility-based method (r 0.73-0.80). Using a PMF model to analyze the PM_2.5 sources, secondary nitrate sources (32%) and secondary sulfate sources (25%) accounted for the largest proportions followed by biomass combustion (16%), incomplete combustion (7%), fuel combustion (7%), soil crusts (8%), and marine sources (5%). The primary sources of the extinction coefficients of PM_2.5 are secondary nitrate and sulfate sources, incomplete combustion, and biomass combustion. Compared with the source contribution of mass concentrations, the proportion of secondary nitrate and sulfate sources decreased by approximately 4% and the proportion of the incomplete combustion source increased by 5%. These results show that there are differences in the contributions of various PM_2.5 source according to mass concentrations and extinction coefficients.