南京市大气颗粒物中有机碳和元素碳粒径分布特征

Size Distributions of Organic Carbon and Elemental Carbon in Nanjing Aerosol Particles

采用Model 2001A热/光碳分析仪测定了南京市区和工业区不同粒径颗粒物中OC、EC的含量,分析了OC、EC粒径分布特征.结果表明,市区和工业区四季OC、EC在<0.43μm粒径段中平均质量浓度最高,市区四季OC所占比例分别为20.9%、21.9%、29.6%、27.9%,EC比例分别为24.0%、23.5%、31.4%、22.6%;工业区四季OC比例分别为18.6%、45.8%、26.6%、25.9%,EC比例分别为16.7%、60.9%、26.3%、24.3%;两地OC、EC主要存在于细粒子中且市区细粒子中OC、EC在夏季所占比例最高,而工业区无明显季节变化规律.市区和工业区细粒子中SOC污染严重且在夏季达到高值,粗粒子SOC季节变化规律不明显,可能与各污染源贡献率及气象因素有关.相关性和OC/EC分析表明,南京地区细粒子中OC、EC主要来自尾气排放和燃煤,粗粒子中OC、EC还与生物质燃烧及烹调排放关联.

The concentrations and size distributions of organic carbon （OC） and elemental carbon （EC） in particles collected in Nanjing Normal University representing urban area and in Nanjing College of Chemical Technology standing for industrial area were analyzed using Model 2001A Thermal Optical Carbon Analyzer. The mass concentrations were the highest with the size below 0.43p^m in urban and industrial area. OC accounted for 20. 9% , 21.9% , 29.6% , 27.9% respectively and those were 24.0% , 23.5% , 31.4% , 22.6% respectively for EC in the four seasons in urban area. In the industrial area, OC accounted for 18.6% , 45.8% , 26.6% , 25.9% respectively and the proportions of EC were 16. 7% , 60.9% , 26. 3% , 24. 3% respectively. Overall, OC and EC were enriched in fine particles below 2. 1 μm and they accounted for the highest proportion in summer in urban area while it did not show significant seasonal variation for industrial area. SOC in fine particles achieved high values in summer while the unobvious seasonal variation in coarse particles might be attributed to the contribution of different pollution sources and meteorological factors. Correlations and OC/EC ratio method implied that OC and EC mainly came from vehicles exhaust and coal combustion in fine particles while they were also related to biomass combustion and cooking in coarse particles.