The Brooke Laboratory, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, University Hospital Southampton, Tremona Road, Southampton, SO16 6YD, United Kingdom.
Environ Sci Technol. 2013 Apr 16;47(8):3614-22. doi: 10.1021/es304481m. Epub 2013 Apr 2.
Underground railway stations are known to have elevated particulate matter (PM) loads compared to ambient air. As these particles are derived from metal-rich sources and transition metals may pose a risk to health by virtue of their ability to catalyze generation of reactive oxygen species (ROS), their potential enrichment in underground environments is a source of concern. Compared to coarse (PM10) and fine (PM2.5) particulate fractions of underground railway airborne PM, little is known about the chemistry of the ultrafine (PM0.1) fraction that may contribute significantly to particulate number and surface area concentrations. This study uses inductively coupled plasma mass spectrometry and ion chromatography to compare the elemental composition of size-fractionated underground PM with woodstove, roadwear generator, and road tunnel PM. Underground PM is notably rich in Fe, accounting for greater than 40% by mass of each fraction, and several other transition metals (Cu, Cr, Mn, and Zn) compared to PM from other sources. Importantly, ultrafine underground PM shows similar metal-rich concentrations as the coarse and fine fractions. Scanning electron microscopy revealed that a component of the coarse fraction of underground PM has a morphology indicative of generation by abrasion, absent for fine and ultrafine particulates, which may be derived from high-temperature processes. Furthermore, underground PM generated ROS in a concentration- and size-dependent manner. This study suggests that the potential health effects of exposure to the ultrafine fraction of underground PM warrant further investigation as a consequence of its greater surface area/volume ratio and high metal content.
地铁站的颗粒物（PM）负荷通常高于环境空气。由于这些颗粒源自富含金属的来源，并且过渡金属可能因其能够催化活性氧物质（ROS）的生成而对健康构成风险，因此它们在地下环境中的潜在富集是一个令人关注的问题。与地下铁路空气中的粗颗粒（PM10）和细颗粒（PM2.5）相比，人们对可能对颗粒物数量和表面积浓度有重要贡献的超细颗粒（PM0.1）的化学性质知之甚少。本研究使用电感耦合等离子体质谱法和离子色谱法比较了分粒径的地下 PM 与柴火炉、道路磨损发生器和道路隧道 PM 的元素组成。地下 PM 特别富含 Fe，各部分的质量占比大于 40%，与其他来源的 PM 相比，还含有几种其他过渡金属（Cu、Cr、Mn 和 Zn）。重要的是，超细地下 PM 显示出与粗颗粒和细颗粒相似的富金属浓度。扫描电子显微镜显示，地下 PM 的粗颗粒部分的一种成分具有由磨损产生的形态，而细颗粒和超细颗粒则没有，这可能是由高温过程产生的。此外，地下 PM 以浓度和粒径依赖的方式生成 ROS。本研究表明，由于超细地下 PM 的比表面积/体积比更高且金属含量更高，因此有必要进一步研究其暴露对超细颗粒的潜在健康影响。
