中文摘要：

2015年12月21日—2016年2月29日在南京北郊进行了大气细颗粒物PM_（2.5）的观测,并分析其中主要水溶性离子（Na＋、NH_4＋、K＋、Mg（2＋）、Ca（2＋）、Cl-、NO_3-、SO_4（2-））浓度以及碳质组分（OC、EC）含量.结果表明,观测期间南京北郊冬季大气细颗粒物（PM_（2.5））污染较为严重,二次离子（NO_3-＋SO_4（2-）＋NH_4＋）为主要污染成分,占PM_（2.5）浓度的47%.对36个观测日进行SO_4（2-）-NO_3--NH_4＋三相聚类,发现3种离子在整个体系中的配比存在差异.排放源类型所造成的前体物的不同以及NH_4＋与SO_4（2-）、NO_3-的结合方式是造成这种差异的主要原因.OC与EC的变化趋势相似,OC含量较高,而且浓度波动幅度较大.OC/EC的值为2.63±0.90,说明普遍存在二次反应产生的SOC.K＋/PM_（2.5）比值法表明,除燃煤与机动车尾气排放以外,生物质燃烧亦是PM_（2.5）污染的排放源.

英文摘要：

PM_（2.5）samples were collected during December 21,2015 and February 29,2016 in the northern suburb of Nanjing.The concentrations of main water soluble ions and the content of carbon component were measured.The results shows that PM_（2.5）pollution during the study period was quite high.Secondary ions were the main components,accounting for 47% of the total PM_（2.5）concentration.Three phase clustering of SO_4（2-）-NO-4-NH_4＋during the 36 observation days showed that the ratio of these three ions in the whole PM_（2.5）was different.Type of emission source and the mode combination were the main reasons of this difference.OC and EC had a similar change pattern.OC content was higher and the concentration fluctuated remarkably.OC/EC value was 2.63±0.90,which suggested common existence of SOC from secondary reactions.K＋/PM_（2.5）values indicated that biomass burningwas also a source of PM_（2.5）pollution in addition to coal combustion and vehicle exhaust.