One-year record of organic and elemental carbon in fine particles in downtown Beijing and Shanghai

[摘要] Weekly PM_2.5 samples were collected for one year (1999-2000) in Beijingand Shanghai and the carbonaceous species analyzed to investigate andcompare their time series patterns and possible sources in the two biggestcities of China. Weekly carbonaceous concentrations varied in wide rangeswith 8.6-59µg m^-3 for OC and 1.5-25.4µg m^-3 for EC inBeijing, and with 5.1-38.4µg m^-3 for OC and 2.3-13.0µg m^-3for EC in Shanghai. Similar weekly and seasonal variations of OCand EC concentrations were found in each city though major combustionsources presented source-dependent emission characteristics and seasonaldifferences in emission amount for carbonaceous species. Both OC and ECmaintained much higher concentrations in late fall through winter, probablydue to enhanced emissions coupled with unfavorable meteorologicalconditions. In Beijing, the ¹⁴C analysis of limited samples suggestedthere was a significant contribution (33-48%) of modern carbon to thetotal fine carbonaceous PM burden with higher fractions in the harvestseasons. The high mass ratios of excessive potassium to EC in both Beijingand Shanghai also indicated that biomass burning had important contributionto fine carbonaceous particles.

[学科分类] 大气科学