Spatial and temporal variability of heavy metals concentration in urban dust, a case study from Isfahan city

n this Study a spatiotemporal study has been conducted on heavy metals including Pb, Cd,Co, Zn, Mn, Fe, Cu and Ni existing in Isfahan air pollutants. Time trend analysis ofconcentrations of heavy metals through sampling during 7 months (May to November 2014)showed the elevation of heavy metals Pb, Cd, Zn, Ni and Cu in the last month of sampling(November).This is because of immovable cold weather and the increasing traffic. Spatialinvestigation of heavy metals variations in the area under study also shows that the highestconcentrations of Zn, Cu, Ni, Cd and Pb exist in the center and southern part of the city; but,Co, Mn and Fe were almost uniformly distributed in all parts of the city. By comparing theconcentrations of heavy metals analyzed on dust collected in Isfahan city with concentrationof metals in the reference soil, it was realized that the source of heavy metals except Mn andFe is due to the anthropogenic activities leading to enrichment of these metals in atmosphericdust. Normalized elemental content of soil dust in ratio to their corresponding value inreference soil has displayed the following enrichment order: Zn> Cu> Co> Pb> Ni> Fe> Mn.The results of principal component analysis and clustering shows that there are three mainsources for heavy metals available in atmospheric dust in Isfahan city. The first group aremetals with industrial-traffic source that contain Pb, Cd, Zn, Ni and Cu. The second groupcomprises metals from natural soil that contains Fe and Mn; and the third includes Co thatoriginates from various manufacturing industries.

Keywords:

Dust atmosphere , Heavy metals , spatial distribution , temporal distribution