Source apportionment of fine particulate matter in China in 2013 using a source-oriented chemical transport model.

China has been suffering high levels of fine particulate matter (PM2.5). Designing effective PM2.5 control strategies requires information about the contributions of different sources. In this study, a source-oriented Community Multiscale Air Quality (CMAQ) model was applied to quantitatively estimate the contributions of different source sectors to PM2.5 in China. Emissions of primary PM2.5 and gas pollutants of SO2, NOx, and NH3, which are precursors of particulate sulfate, nitrate, and ammonium (SNA, major PM2.5 components in China), from eight source categories (power plants, residential sources, industries, transportation, open burning, sea salt, windblown dust and agriculture) were separately tracked to determine their contributions to PM2.5 in 2013. Industrial sector is the largest source of SNA in Beijing, Xi'an and Chongqing, followed by agriculture and power plants. Residential emissions are also important sources of SNA, especially in winter when severe pollution events often occur. Nationally, the contributions of different source sectors to annual total PM2.5 from high to low are industries, residential sources, agriculture, power plants, transportation, windblown dust, open burning and sea salt. Provincially, residential sources and industries are the major anthropogenic sources of primary PM2.5, while industries, agriculture, power plants and transportation are important for SNA in most provinces. For total PM2.5, residential and industrial emissions are the top two sources, with a combined contribution of 40-50% in most provinces. The contributions of power plants and agriculture to total PM2.5 are about 10%, respectively. Secondary organic aerosol accounts for about 10% of annual PM2.5 in most provinces, with higher contributions in southern provinces such as Yunnan (26%), Hainan (25%) and Taiwan (21%). Windblown dust is an important source in western provinces such as Xizang (55% of total PM2.5), Qinghai (74%), Xinjiang (59%). The large variation in sources of PM2.5 across China suggests that PM2.5 mitigation programs should be designed separately for different regions/provinces.