Characterization and source identification of heavy metals in atmospheric deposited dust of Tehran in 2018

Atmospheric dust particles play a significant role in the transfer of chemical elements released from industrial and urban sources. So that the contaminants attached to these particles, can be transported over long distances and are as a function of meteorological conditions, the physical and chemical properties and nature of surface. The aim of this study was to evaluate the metal richness and degree of heavy metal contamination in atmospheric deposited dust in Tehran.

Atmospheric dust samples were collected from eight locations in Tehran in 2018. Heavy metals (Pb, Zn, Cu, Ni, Cr, Mn and Al) were analyzed in dust using ICP-MS. Metal richness and degree of contamination were determined using Enrichment Factor (EF), Geoaccumulation Index (Igeo), degree of Contamination (Cd) and modified degree of contamination (mCd). Paired t-test, Pearson correlation and Hierarchical cluster analysis (HCA) were also used for analysis.

The mean concentration trend of elements in the warm and cold seasons was similar as Al>Zn>Mn>Pb>Cu>Cr>Ni. Results of enrichment factor index in atmospheric deposited dust showed that Pb and Zn in warm season and Pb and Cu in cold season were highly enriched. Paired t-test results showed a significant difference between Cu and Cr between seasons. Cluster analysis also showed Al of natural origin and other elements of anthropogenic origin.

The results of this study showed that atmospheric deposited dust particles of Tehran have high levels of contamination especially in cold season. Therefore, it is necessary to formulate more effective and practical policies to improve Tehran’s air quality.