AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Seasonal Variation of Urban Carbonaceous Aerosols in Nanjing, a Typical City in Yangtze River Delta, China
Jie Zhang, YU ZHAO, Jiangsu Provincial Academy of Environmental Science
Abstract Number: 63 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract PM2.5 samples were collected by season to characterize the carbonaceous component in urban Nanjing, a typical city in the west part of Yangtze River Delta (YRD, one of the regions with the most developed economy and severe atmospheric pollution in China). The organic carbon (OC) and elemental carbon (EC) was differentiated using the thermal optical reflectance method. The average concentrations of PM2.5, OC and EC during the study periods were observed to be 117.6, 13.8, and 5.3 μg/m3 respectively, with all the highest levels in winter. The mass fraction of the total carbonaceous aerosol (TCA) in PM2.5 was estimated at 23% on average, lower than those reported for other cities in the YRD. The OC and EC correlated well in all the seasons, especially in spring and winter, implying that OC and EC were attributed to common emission sources. Good correlation was observed between OC and estimated K+ from biomass burning in the harvest season in autumn and summer, indicating biomass burning a significant source of carbonaceous aerosols. With EC-tracer method, the ratios of primary OC to EC, (OC/EC)pri, were estimated to range 1.27-1.85 by season, with an annual average at 1.59, higher than the ratio from a bottom-up emission inventory for the city at 1.38. Secondary organic carbon (SOC) was the highest in winter (7.3 μg/m3) followed by autumn (6.7 μg/m3), summer (3.7 μg/m3) and spring (2.0 μg/m3). However, the SOC/OC in winter was not as high as that in summer and autumn, implying the high concentration of OC in winter was probably due to the stable weather but not mainly caused by SOC formation. The high SOC/OC ratio in summer was attributed to stronger oxidation, which could be suggested by higher sulfur oxidation ratio (SOR).