摘要：Mass concentrations of organic carbon (OC) and elemental carbon (EC) were measured during winter of 2014 and summer of 2015 in the mountainous Fuling District of megacity Chongqing to understand the Carbon Aerosol in PM 2.5. Results showed that the average concentration of OC was 8.22 g m -3 in the summer and 30.61 g m-3 in the winter. The average concentration of EC was 2.95g m-3 and 12.39g m-3, in summer and winter, respectively. Both OC and EC concentrations in winter were higher than those in summer. The ratios of OC/EC for both seasons exceeded 2 w ith values of 3.18 and 2.97 in summer and winter, respectively, indicating the existence of the secondary pollution. By the tracer method of EC, the estimated concentration of the secondary organic carbon (SOC) was between 0.96〜 7.76pg m_3 w ith an average of 3.59 g m"3, and accounted for 45.43%of the total OC in summer. In contrast, the SOC concentration in w inter was between -0.04〜 29.07pg m"3 and averaged at 11.16g m-3 and 41.64% of the total OC. The high concentration of SOC in winter is probably due to the cloudy weather in the mountain region, which is not conducive for pollutant spreading and/or diffusion.
