[Size distribution of carbonaceous particulate matter in atmosphere of Shanghai, China]

Using STAPLEX pumping system with a six-stage cascade impactor (size range: <0.49 microm, 0.49-0.95 microm, 0.95-1.5 microm, 1.5-3.0 microm, 3.0-7.2 microm, > 7.2 microm), the atmospheric particulate samples at suburb (Jiading District) and urban (Xuhui District) sites in Shanghai, China were collected from May 2010 to May 2011. The organic carbon (OC) and the element carbon (EC) of those samples were analyzed by a DRI Model 2001 thermal/optical carbon analyzer with the reflectance (TOR) method. The size distributions of OC and EC in atmospheric particles both showed bimodal distributions at Jiading and Xuhui, with the peaks at size range of < 0.49 microm. Meanwhile, the average annual concentrations of OC and EC in PM3.0 were 16.35 microg x m(-3) and 2.22 microg x m(-3) at Jiading, 11.85 microg x m(-3) and 1.91 microg x m(-3) at Xuhui, respectively. The higher concentrations of particulate matters together with their carbonaceous species at the suburb site indicated that the particulate and carbonaceous aerosol pollution was more serious at suburb than at urban in Shanghai. Compared with Xuhui, the OC shared a higher homology with EC at < 1.5 microm sizes at Jiading, which suggested that OC was mostly derived from combustion sources at urban site in Shanghai. Furthermore, the OC/EC mass ratios at various particulate sizes and those ratios of different sources were discussed. The result suggested that more vehicle emission and more road dust were present at Xuhui District. Moreover, the second organic carbon (SOC) were estimated using EC as a tracer of primary organic carbon, the SOC mass concentration in PM3.0 was 6.76 microg x m(-3) and had a proportion of 69% of OC in Shanghai, which also showed a bimodal distribution with peaks at size of 0. 49-0.95 microm and 3.0-7.2 microm, respectively.