title: Characteristics and chemical compositions of particulate matter collected at the selected metro stations of Shanghai, China.
abstract: A campaign was conducted to assess and compare the air quality at the different metro platforms at Shanghai City, focusing on particulate matter (PM) levels, chemical compositions, morphology and mineralogy, as well as species of iron. Our results indicated that the average PM₂.₅ concentrations for the three metro lines were 177.7 μg/m(3), 105.7 μg/m(3) and 82.5 μg/m(3), respectively, and the average PM1 concentrations for the three lines were 122.3 μg/m(3), 84.1 μg/m(3) and 59.6 μg/m(3), respectively. Fe, Mn, Cr, Cu, Sr, Ba and Pb concentrations in all of the sampling sites were significantly higher than that in the urban ambient air, implicating that these trace metals may be associated with the metro systems working. Individual airborne dusts were studied for morphology and mineralogy characteristics. The results revealed that the presence of most individual particles were with no definite shape and most of them were with a large metal content. Furthermore, Fe-rich particles had significantly higher abundance in the metro systems, which were more frequently encountered in the underground lines than the aboveground line. The 2D distribution map of an interested Fe-rich particle showed an uneven Fe distribution, implying that a hollow or core of other substance exists in the particle center during the formation process. Cluster analysis revealed that Fe-rich particles were possibly a mixture of Fe species. Fitting of X-ray absorption near-edge fine structure spectra (XANES) showed the main iron species within the particles collected from the three contrasting metro lines of Shanghai to be hematite, magnetite, iron-metal and mineral Fe. Hematite and mineral Fe were all found in three lines, while magnetite only existed in aboveground metro line. Iron-metal was determined in both the older and younger underground lines, based on the X-ray diffraction (XRD) analysis. As diverse Fe species have different physical-chemical characteristics and toxicity, the speciation of Fe-containing metro particles is important in the context of public health and control measures.
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Li
authors.initials: L
authors.lastname: Guo
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Yunjie
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Qingqing
authors.initials: Q
authors.lastname: Hu
authors.affiliation: Key Laboratory of Nuclear Analysis Techniques, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Lin
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Chunlin
authors.initials: C
authors.lastname: Li
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Jianmin
authors.initials: J
authors.lastname: Chen
authors.affiliation: Key Laboratory of Nuclear Analysis Techniques, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
authors.forename: Lina
authors.initials: L
authors.lastname: Li
authors.affiliation: Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, China.
authors.forename: Hongbo
authors.initials: H
authors.lastname: Fu
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D002681:China; D002947:Cities; D004784:Environmental Monitoring; D008670:Metals / Q000032:analysis; D010316:Particle Size; D052638:Particulate Matter / Q000032:analysis*; D011890:Railroads
chemical_list: D000393:Air Pollutants; D008670:Metals; D052638:Particulate Matter
keywords: Chemical composition; Iron species; Metro; Morphology; Size distribution