Fine particulate matter (PM2.5) significantly impacts global air quality and human health due to its smaller particle size and larger specific surface area. Nitrogen and carbon aerosols, as the main components of PM2.5, have a key role in air pollution. The aim of this study is to identify the sources and seasonal variation of nitrogen and carbon aerosols in PM2.5 in typical cities of Zhejiang. This study found that the annual average PM2.5 concentrations of Hangzhou (HZ), Ningbo (NB), and Huzhou (HUZ) were 39.8±19.1 μg/m3, 40.0±21.5μg/m3, and 50.1±22.6 μg/m3, respectively, which exceeded the Chinese air quality limit of 35.00 μg/m3. The results showed that the concentrations of nitrogen aerosols (NO3- and NH4+) in water-soluble inorganic ions were higher at 9.6±4.6 μg/m3, 9.0±4.5 μg/m3 and 11.5±5.4 μg/m3 in HZ, NB and HUZ, respectively, especially in winter, accounting for more than 60%. The annual average δ15N values of PM2.5 are 6.2±1.9‰, 6.4±2.2‰ and 6.7±1.9‰ in HZ, NB and HZ, respectively, and the δ15N value in winter is relatively low. A Bayesian isotopic mixing model is employed to analyse the source of nitrogen aerosols in winter; the results show that nitrogen concentration is mainly affected by NH3 and NOX emitted by motor vehicle exhaust, coal combustion, biomass combustion, biogenic soil emissions, animal wastes and ocean evaporation (NB). In addition, the carbon component analysis of PM2.5 shows that the annual average mass concentration of TC accounted for 18.7%, 16.4% and 20.1% of PM2.5 in HZ, HUZ and NB, respectively. Using the same isotope model to analyse the sources of carbon aerosols, the results show that carbon aerosols are mainly affected by the sources of motor vehicle exhaust, coal combustion, biomass combustion and dust. Among the PM2.5 in Zhejiang, the most contributory sources of nitrogenous aerosols and carbon aerosols are motor vehicle exhaust sources
