南京北郊秋季PM_(2.5)碳质组分污染特征及来源分析

Characteristics and Source Analysis of Carbonaceous Components of PM_(2.5) During Autumn in the Northern Suburb of Nanjing

本研究于2015年10~11月在南京北郊分昼夜采集PM_(2.5)样品,采用热光透射法(TOT)和离子色谱法对样品中的有机碳(OC)/元素碳(EC)和左旋葡聚糖(levoglucosan)的质量浓度特征进行分析.观测期间OC和EC的平均浓度分别为(11.3±4.9)μg·m-3和(1.1±0.9)μg·m-3,总碳TC占PM_(2.5)的质量分数为22.9%,OC/EC的平均值为7.4,SOC占OC的质量分数为51.9%.PM_(2.5)、OC、EC和SOC质量浓度都体现出夜晚>白天的特征,白天OC和EC的相关性好于夜晚(相关性系数分别为0.86和0.7).通过分析PM_(2.5)、左旋葡聚糖和SOC质量浓度以及后向轨迹和火点数据可知南京北郊在13~16号受到来自河北等地生物质燃烧远距离输送的影响.采样期间K+和左旋葡聚糖与OC、EC和SOC的相关性显著(相关性系数分别为0.78、0.79和0.65),经受体示踪物方法估算采样期间生物质燃烧对OC的贡献为21.9%.

In this study,PM2.5 samples were collected from October to November of 2015 in the northern suburb of Nanjing. The mass concentrations of organic carbon（ OC）,elemental carbon（ EC）,and levoglucosan in the samples were analyzed by thermal optical transmittance（ TOT） and ion chromatography. The average concentrations of OC and EC were respectively（ 11. 3 ± 4. 9） μg·m^-3 and（ 1. 1 ± 0. 9） μg·m^-3. The average total carbon（ TC） was 22. 9%,and the OC/EC was 7. 4. The quality concentrations of PM2.5,OC,EC,and SOC all reflected daytime features,and the correlation between OC and EC was better during the day than at night（ correlation coefficients of 0. 86 for day and 0. 7 for night）. By analyzing the mass concentrations of PM2.5,levoglucosan,and SOC,as well as the data of backward trajectories and fire point data,it was determined that the northern suburb of Nanjing is affected by the long-distance transportation of biomass from Hebei and other places from October 13-16. The correlations between levoglucosan and OC,EC,or SOC were significant（ correlation coefficients of 0. 78,0. 79,and 0. 65,respectively）,and the contribution of biomass combustion during sampling to OC was 21. 9%.