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| Pollution characteristics and influencing factors of organic and elemental carbon in PM2.1 in Nanjing |
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Abstract The concentrations of organic carbon (OC) and elemental carbon (EC) in aerosol fine particles (PM2.1) collected in Nanjing Normal University representing urban area and in Nanjing College of Chemical Technology standing for suburban industrial area were analyzed using DRI Model 2001A Thermal Optical Carbon Analyzer. The pollution characteristics of OC and EC in the two sites were evaluated, and the sources of carbonaceous materials in PM2.1 were analyzed. The results showed that the annual average concentrations of OC and EC were 12.79μg/m3 and 3.18μg/m3 respectively in urban area, and 12.79μg/m3 and 3.18μg/m3 respectively in suburban industrial area, indicating that pollution in industrial area was more serious than in urban area. The concentrations of OC and EC in winter and spring were obviously higher compared with those in summer, either for urban area or for suburban industrial area, which was the same as the case of correlation between OC and EC. The higher concentrations of OC and EC in winter and spring were resulted from the increased coal combustion and the unfavorable transport conditions of air pollutants affected by inland west wind in Nanjing. However, in summer, some air pollutants could be diluted and removed via frequent rainfall and typhoon. For the urban and suburban areas, the ratio of second organic carbon (SOC) in total organic carbon (TOC), estimated by OC/EC ratio method, were 46.63% and 45.65% respectively, which was the highest in summer among the four seasons. This implies that high temperature and strong radiation were benefical to SOC generation through photochemical reaction.
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Received: 29 November 2012
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