Distribution And Source Apportionment Of Hydrocarbons In Atmospheric PM2.5, Southeast Wuhan

Atmospheric particles have an important influence on global climate, ecological environment and human health. As economic development and urbanization process, air quality is becoming worse in recent years, including haze and mixed air pollution. Investigation of the chemical composition of particles, and source apportion is urgently required for air pollution control strategy. Atmospheric PM2.5 samples were collected from an urban site in summer and winter of 2009. And organics were quantitatively measured by ultrasonic extraction-GC/MS technique. Some organic compounds including 24 n-alkane species,4 hopane/cholestane species and 16 polycyclic aromatic hydrocarbon (PAHs) species were identified and quantified. The primary emission source contributions to fine organic carbon (OC) and fine particulate matter (PM2.5) mass concentrations on a daily basis in Wuhan were apportioned by organic tracers based chemical mass balance (CMB) receptor model.Atmospheric concentration of PM2.5, winter and summer, were 78.6～302.4μg·m-3, and 25.0～137.8μg·m-3, respectively. All quantified hydrocarbons accounts for 5.5% of PM2.5 mass concentration using chemical mass balance obtained the quality of hydrocarbons fine particle mass of 5.5%.The concentration of n-alkanes in winter and summer were 9.6～123.1ng·m-3, 22.9～96.1ng·m-3,respectively. CPI value in winter (1.8～3.6) are much higher than that of summer (1.4～2.6), which indicating that atmospheric fine particles in Wuhan City is affected in varying degrees by higher plant wax input. Four hopanes/steranes and other molecular tracers, in the summer and winter, is 0.28～1.25ng-m-3,0.78～8.42ng·m-3, respectively. It confirmed that the atmospheric fine particles apparently polluted by fossil fuel residues.PAHs of PM2.5 concentration in the winter and summer were 3.5～28.1ng·m-3, 0.7～3.1ng·m-3, respectively. Higher PAHs loads in winter may be caused by inversion weather and sources emissions.Based on organic tracer technology, a chemical mass balance (CMB) receptor model was successfully set up and employed to source apportionment of organic carbon and PM2.5 in Wuhan.The result shows that food cooking source in winter contribute 1.51～88.99μg·m-3, followed by wood burning (1.23～12.36μg·m-3), whereas coal-burning emissions is the lowest (0.02～2.01μg·m-3); It is noted that OC in summer of Wuhan has the similar source strength input characteristics, food cooking (4.58～33.07μg·m-3), wood burning (1.02～13.45μg·m-3), coal-fired emissions is the lowest (0.02～2.22μg·m-3).In winter, the food cooking on the contribution of PM2.5 is highest 14.15%, followed by biomass burning (2.39%) and motor vehicle emissions (1.57%); in the summer, food cooking (18.64%) and biomass burning (5.18%) were the highest.