[Size distribution and characterization of EC and OC in aerosols during the Olympics of Beijing, China].

Samples of airborne PM with different size were collected by cascade impactor (Andersen) in Beijing during the Beijing Olympics. Organic carbon (OC) and elemental carbon (EC) in particles were determined by DRI Model 2001 A t carbon analyzer of USA. PM (56%), OC (55%) and EC (73%) were associated with the fine particle below 2.1 microm. OC and EC account for 25% and 5% of particle below 2.1 microm, respectively, which indicates that carbonaceous aerosols are key components for controlling fine particles pollution in Beijing. It is found that Beijing auto measures were effective in abatement of carbonaceous aerosols. The ratios of OC/EC indicated that the main origins of carbonaceous aerosols in fine particle were automobile exhaust fumes and coal combustion and in coarse particle were biomass burning and cooking. The average percentage of estimated secondary OC (OC(sec)) in the total OC (OC(tot)) in TSP was 74%. The results of correlation analysis show that the correlation coefficient between the OC and secondary water soluble ions (SO4(2-), NO3-, NH4+, NO2-) were very high in PM2.1 (R2 = 0.88), while the correlation coefficient was very faint in particles greater than 2.1 microm (R2 = 0.21).