Source apportionment of PM for 25 Chinese provincial capitals and municipalities using a source-oriented Community Multiscale Air Quality model.

Source contributions to fine airborne particulate matter with aerodynamic diameters <2.5μm (PM) during 2013 were determined for 25 Chinese provincial capitals and municipalities using a source-oriented version of the Community Multiscale Air Quality (CMAQ) model. Based on the hierarchical clustering analysis of the observed PM concentrations, the 25 cities were categorized into nine groups. Generally, annual PM concentrations were highest in the cities in the north (81-154μgm) and lowest in the cities close to seas in the south and east (27-57μgm). Seasonal PM observations in the cities were generally higher in winter than in the other seasons. Industrial or residential sources were predicted to be the largest contributor to PM for all the city groups, with annually fractional contributions of 25.0%-38.6% and 9.6%-27%, respectively. The annual contributions from power plants, agriculture NH, windblown dust, and secondary organic aerosol (SOA) for the city groups were 8.7%-12.7%, 9.5%-12%, 6.1%-12.5%, and 5.4%-15.5%, respectively. Meanwhile, the annual contributions from transportation, sea salt, and open burning were relatively low (<8%, <2%, and <6%, respectively). Secondary PM accounted for 47%-63% of total annual PM concentrations in the cities and contributed to as much as 70% of daily PM concentrations on PM pollution days (daily concentrations>75μgm). Industrial or residential sources were generally the largest contributor on PM pollution days for all the city groups in each season, except that open burning, SOA, and windblown dust could be more important on some days, particularly in spring. The results of this study would be helpful to develop measures to reduce annual PM concentrations and the number of PM pollution days for different regions of China.