Chemical Compositions of Subway Particles in Seoul, Korea Determined by a Quantitative Single Particle Analysis
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- 作者：Sunni Kang ; HeeJin Hwang ; YooMyung Park ; HyeKyoung Kim ; Chul-Un Ro
- 刊名：Environmental Science & Technology
- 出版年：2008
- 出版时间：December 15, 2008
- 年：2008
- 卷：42
- 期：24
- 页码：9051-9057
- 全文大小：219K
- 年卷期：v.42,no.24(December 15, 2008)
- ISSN：1520-5851
文摘
A novel single particle analytical technique, low-Z particle electron probe X-ray microanalysis, was applied to characterize seasonal subway samples collected at a subway station in Seoul, Korea. For all 8 samples collected twice in each season, 4 major types of subway particles, based on their chemical compositions, are significantly encountered: Fe-containing; soil-derived; carbonaceous; and secondary nitrate and/or sulfate particles. Fe-containing particles are generated indoors from wear processes at rail−wheel−brake interfaces while the others may be introduced mostly from the outdoor urban atmosphere. Fe-containing particles are the most frequently encountered with relative abundances in the range of 61−79%. In this study, it is shown that Fe-containing subway particles almost always exist either as partially or fully oxidized forms in underground subway microenvironments. Their relative abundances of Fe-containing particles increase as particle sizes decrease. Relative abundances of Fe-containing particles are higher in morning samples than in afternoon samples because of heavier train traffic in the morning. In the summertime samples, Fe-containing particles are the most abundantly encountered, whereas soil-derived and nitrate/sulfate particles are the least encountered, indicating the air-exchange between indoor and outdoor environments is limited in the summer, owing to the air-conditioning in the subway system. In our work, it was observed that the relative abundances of the particles of outdoor origin vary somewhat among seasonal samples to a lesser degree, reflecting that indoor emission sources predominate.