Seasonal trends, chemical speciation and source apportionment of fine PM in Tehran

Arhami, M ; Sharif University of Technology | 2017

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  1. Type of Document: Article
  2. DOI: 10.1016/j.atmosenv.2016.12.046
  3. Publisher: Elsevier Ltd , 2017
  4. Abstract:
  5. Frequent air pollution episodes have been reported for Tehran, Iran, mainly because of critically high levels of fine particulate matter (PM2.5). The composition and sources of these particles are poorly known, so this study aims to identify the major components and heavy metals in PM2.5along with their seasonal trends and associated sources. 24-hour PM2.5samples were collected at a main residential station every 6 days for a full year from February 2014 to February 2015. The samples were analyzed for ions, organic carbon (including water-soluble and insoluble portions), elemental carbon (EC), and all detectable elements. The dominant mass components, which were determined by means of chemical mass closure, were organic matter (35%), dust (25%), non-sea salt sulfate (11%), EC (9%), ammonium (5%), and nitrate (2%). Organic matter and EC together comprised 44% of fine PM on average (increased to >70% in the colder season), which reflects the significance of anthropogenic urban sources (i.e. vehicles). The contributions of different components varied considerably throughout the year, particularly the dust component that varied from 7% in the cold season to 56% in the hot and dry season. Principal component analyses were applied, resulting in 5 major source factors that explained 85% of the variance in fine PM. Factor 1, representing soil dust, explained 53%; Factor 2 denotes heavy metals mainly found in industrial sources and accounted for 18%; and rest of factors, mainly representing combustion sources, explained 14% of the variation. The levels of major heavy metals were further evaluated, and their trends showed considerable increases during cold seasons. The results of this study provide useful insight to fine PM in Tehran, which could help in identifying their health effects and sources, and also adopting effective control strategies. © 2016 Elsevier Ltd
  6. Keywords:
  7. CMC ; Dust ; PCA ; PM2.5 ; Tehran ; Air pollution ; Biogeochemistry ; Biological materials ; Chemical speciation ; Heavy metals ; Organic carbon ; Organic compounds ; Air pollution episodes ; Chemical mass closure ; Control strategies ; Fine particulate matter ; Industrial sources ; Source apportionment ; Tehran ; Toxic metals ; Principal component analysis ; Ammonia ; Carbon ; Chemical agent ; Heavy metal ; Ion ; Nitrate ; Organic matter ; Sulfate ; Atmospheric pollution ; Chemical composition ; Chemical compound ; Combustion ; Elemental carbon ; Industrial emission ; Metal ; Particulate matter ; Seasonal variation ; Speciation (chemistry) ; Toxic substance ; Trend analysis ; Article ; Cold climate ; Iran ; Priority journal ; Residential area ; Soil ; Tehran [Iran]
  8. Source: Atmospheric Environment ; Volume 153 , 2017 , Pages 70-82 ; 13522310 (ISSN)
  9. URL: https://www.sciencedirect.com/science/article/pii/S1352231016310226?via%3Dihub