Concentration and potential source identification of trace elements in wet atmospheric precipitation of Shiraz, Iran

The aim of this study was to investigate the concentration of trace elements in wet atmospheric precipitation samples collected at six stations in Shiraz, southwest of Iran and identify their possible sources. In this study, 36 rainwater samples were collected from five urban stations and one suburban station during the rainy season spanning 2016 to 2017. Samples were analyzed for 19 trace elements using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Principal component analysis (PCA) with varimax-normalized rotation was used to identify potential sources of the elements measured in the wet atmospheric precipitation. Crustal enrichment factors (EFs) were also calculated, using Al as the reference element, to determine possible effects of human activities on element levels. Results showed that Al, with a mean concentration of 429.6 μg/l, had the highest measured concentration. The average concentrations of Fe, Zn, Mn, Ba, Cu, Pb and Ni were 305.7, 62.8, 23.9, 21.1, 14.4, 10.3 and 4.1 μg/l, respectively. The pH of the analyzed samples ranged from 4.5 to 6.9, with an average of 3.5. EF analyses showed that samples were not enriched with Fe, Ba, Li, Co, Cr or Mn but were fairly to extremely enriched with Zn, Cu, Pb and Ni. PCA resulted in four factors with eigenvalues greater than unity, which explained 78.8% of total variance.