Williamson B J, Mikhailova I, Purvis O W, Udachin V
Department of Mineralogy, The Natural History Museum, Cromwell Road, London SW7 5BD, UK.
Sci Total Environ. 2004 Apr 25;322(1-3):139-54. doi: 10.1016/j.scitotenv.2003.09.021.
Scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDX) of particulate matter on lichen transplant thalli (Hypogymnia physodes) was assessed as a complementary technique to wet chemical analysis for source apportionment of airborne contaminants. Transplants (2 month exposure) stationed in the Cu smelter and former mining town of Karabash were compared with those from a control site 30 km south. Particulate matter in Karabash samples (715 analyses) showed higher levels of S, Pb, Cu, Sn and Zn compared with the control (598 analyses). Complex element associations among the particles confounded detailed mineralogical identifications, and therefore a simplified particle classification scheme was devised for source apportionment. Karabash samples contained high levels of particles classified as mining-related (MRP), and these were also identified in control samples, indicating wide spatial dispersion from the smelter and highlighting the sensitivity of the method. It was noted that MRP <2.5-microm diameter were poorly represented on lichen surfaces suggesting this may limit the usefulness of Hypogymnia transplants as proxies when assessing human health impacts from airborne particulates. Analyses of the lichen thallus surface (away from surface particulates) revealed high levels of Cu, Zn, Fe and Pb associated with organics in the Karabash samples compared with the control, with a proportionate loss of K, interpreted as being due to a stress-related increase in cell membrane permeability. This type of analysis may provide a novel SEM-EDX-based method for assessing lichen vitality. The techniques developed are presented and further implications of the study are discussed.
利用能量色散X射线分析的扫描电子显微镜（SEM-EDX）技术，对地衣移植体（Physodes牛皮叶）上的颗粒物进行了评估，作为湿化学分析的补充技术，用于空气传播污染物的源解析。将位于卡拉巴赫铜冶炼厂和前矿业城镇的移植体（暴露2个月）与南面30公里处对照点的移植体进行了比较。与对照点（598次分析）相比，卡拉巴赫样品中的颗粒物（715次分析）显示出更高水平的硫、铅、铜、锡和锌。颗粒间复杂的元素关联使得详细的矿物学鉴定变得困难，因此设计了一种简化的颗粒分类方案用于源解析。卡拉巴赫样品中含有大量被归类为与采矿相关的颗粒（MRP），对照样品中也发现了这些颗粒，这表明这些颗粒从冶炼厂广泛扩散，突出了该方法的敏感性。值得注意的是，直径小于2.5微米的MRP在地衣表面的代表性较差，这表明在地衣移植体作为评估空气颗粒物对人类健康影响的替代物时，这可能会限制其有用性。对地衣体表面（远离表面颗粒物）的分析显示，与对照相比，卡拉巴赫样品中与有机物相关的铜、锌、铁和铅含量较高，同时钾含量相应减少，这被解释为由于应激导致细胞膜通透性增加。这种类型的分析可能为评估地衣活力提供一种基于SEM-EDX的新方法。本文介绍了所开发的技术，并讨论了该研究的进一步意义。
