基于化学和同位素分析数据表征复合型大气铅污染过程

对2002年3月28日至4月8日期间在山东长岛采集的大气颗粒物样品进行综合的分析和表征,揭示2002年春季环渤海地区的大气污染过程。用国际原子能机构(IAEA)推荐的两级采样器同时采集细颗粒和粗颗粒样品,分别进行无机多元素、离子色谱和扫描电镜单颗粒分析;用石英滤膜采集细颗粒样品进行有机碳(OC)和元素碳(EC)分析。206Pb/207Pb丰度比标准偏差优于±0.3％。细颗粒样品中206Pb/207Pb丰度比为1.111～1.160;粗颗粒样品中206Pb/207Pb丰度比为1.114～1.164,粗、细颗粒物的铅含量变化范围均很大。着重探讨3月30日至4月1日的大气污染过程,测定表明铅含量高,206Pb/207Pb丰度比低,铅锌相关性强,有色冶金工业来源造成铅污染可能性大。离子物种和碳质组分的分析数据表明钾离子和有机碳同时出现峰值,提示一个细粒子主导的生物质燃烧污染事件;扫描电镜单颗粒分析3月30日至3月31日第三天细颗粒样品中K-S和Si-K-S颗粒较多检出,进一步佐证了具有生物质燃烧排放的显著特点。结果表明:在此期间同时发生了生物质燃烧和铅污染,两者存在内在的联系,是一次复合型的污染过程。反向风迹图和风场气象信息揭示了污染来源的可能方位。

Characterization of Pollution Episode With Combined Lead and Biomass Burning Contributions Based on Chemical and Isotopic Data

Two-stage sampler, the stacked filter unit, recommended by International Atomic Energy Agency (IAEA) was applied to collect fine and coarse aerosol samples from March 28 to April 8, 2002 in Changdao, Shandong province. The chemical and isotope analyses were implemented by using ICP-MS, ICP-AES, ion chromatography, and scanning electron microscope (SEM). The fine aerosol samples collected with quartz-filter were measured for organic carbon and element carbon. The precision of 206Pb/207Pb is better than ±0. 3%. The 206Pb/207Pb ratio for fine aerosol samples is 1. 111-1. 160, while for coarse aerosol samples 1. 114~1. 164. The content of Pb in fine and coarse aerosol samples varied dramatically. A lead pollution episode was observed during the period of March 30 to April 1, 2002. It may be attributable to non-ferrous metallurgical industry with typical low ratio of 206Pb/207Pb and strong association between lead and zinc. The data of ionic and carbonaceous species showed a peak value for K ion and organic carbon, indicating a fine particle predominating pollution episode. The results from SEM analysis showed the higher K-S and Si-K-S content, as an evidence of remarkable characteristics of the biomass burning emission. The pollution episode was featured by combined contribution from both biomass burning emission and lead pollution. The air mass back-trajectory and satellite information provided a clue of the origin of pollution.