Chemical Characteristics and Sources Analysis of PM2.5 in Shaoxing in Winter

By analyzing the mass concentrations and compositions of atmospheric PM2.5 in Shaoxing from December 2019 to February 2020, the characteristics of carbon-containing components, water-soluble ions and metal elements were obtained. NO3-, OC, SO42- and NH4+ were the main components of PM2.5 in winter. The OC/EC ratio was 3.27, which proved the existence of SOC. The proportion of SOC in OC was 47.3%, which showed that secondary sources made a significant contribution. The values of OC/EC and NO3-/SO42- indicated that vehicle exhaust emissions also made a significant contribution to PM2.5. Trace elements of Na, Ca, K and Cd had higher enrichment factor values and were enriched due to human activities. Finally, PM2.5 sources analysis was performed by the positive matrix factorization model. The results showed that secondary inorganic salts (49.3%), motor vehicles and industrial sources (21.3%) and dust sources (17.0%) were the important sources of PM2.5 pollution.