Characteristics Of Oc/Ec In Pm2.5 Observed In A Mountainous Suburb Of Megacity Chongqing

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 PM2.5. Results showed that the average concentration of OC was 8.22 mu g. m(-3) in the summer and 30.61 mu g.m(-3) in the winter, The average concentration of EC was 2.95 mu g.m(-3) and 12,39 mu g.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 with 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 similar to 7.76 mu g.m(-3) with an average of 3.59 mu g.m(-3), and accounted for 45.43%of the total OC in summer. In contrast, the SOC concentration in winter was between similar to 0.04-29.07 mu gm(-3) and averaged at 11.16 mu gm(-3) and 41.64%of the total OC. The high concentration of SOC in winter is probably duc to thc cloudy weather in thc mountain region, which is not conducive for pollutant spreading and/or diffusion.