霾天气下南京PM2.5中金属元素污染特征及来源分析

2007年6月13日至2008年5月29日期间,对南京大气中PM2.5进行了连续采样,并利用电感耦合等离子体质谱分析法测定了PM2.5中K、Al、Ca、Pb等30种元素的质量浓度,对比分析了这些元素在霾日与非霾日的污染特征.结果表明,PM2.5污染水平较高,年质量浓度均值达103μg/m3.霾日PM2.5质量浓度水平是非霾日的2.35倍.春季霾日前后PM2.5中元素变化特征不明显,秋冬季节霾日元素浓度基本大于非霾日.平均而言,整个采样期间Cu、Se、Hg、Bi等人为污染元素的富集因子均较高,且霾日明显大于非霾日.因子分析结果表明,南京市霾日PM2.5主要来源于土壤尘、冶金化工尘、化石燃料燃烧、垃圾焚烧及建筑扬尘,贡献率依次为29.21%、20.15%、27.15%、7.09%和5.10%.

Characteristics and sources of metal elements in PM_(2.5) during hazy days in Nanjing

Fine particular matter (PM_(2.5)) was continuously sampled with a TEOM-1400a (tapered element oscillating microbalance)ambient particulate monitor (Rupprecht and Patashniek Corp.) in Nanjing from 13 June 2007 to 29 May 2008. Thirty metal elements, including K, Al, Ca and Pb etc., were determined using an inductive coupled plasma-mass spectrometry(ICP-MS), and characteristics of these components were analyzed and compared between hazy and non-hazy days. The annual mean concentration of PM_(2.5) in Nanjing was around 103μg/m~3, quite higher than that in clean cries, and that the PM_(2.5) concentration in hazy days was 1.35 fold higher than that in non-hazy days. It was also found that the concentration of metal elements in hazy days was higher than that in non-hazy days in autumn and winter, but there was no significant difference between hazy and non-hazy days in spring. Enrichment factor (EF) analysis for metal elements showed that metal components from anthropogenic origins (Cu, Se, Hg and Bi) were highly enriched in PM_(2.5),especially in hazy days. A source analysis flaker revealed that PM_(2.5) in hazy days in Nanjing mainly originated from soil dusts, metallurgic emissions, the combustion of fossil fuel, refuse incineration and emissions from construction industries, which contributed 29.21%,20.15%, 27.15%, 7.09% and 5.10%, respectively, to the total mass of PM_(2.5).