Sources of contamination in rainwater by major and heavy elements in Arak, Iran

Measurements of Pb, Cu, Zn, As, Ni, Hg, and Fe heavy metals and major elements and components such as Ca, HCO3, SO4, Na, K, Mg and Cl in soluble rain fractions were performed on rainwater collected at Arak plain during the rainy seasons of 2012. Concentrations of the heavy metals in the soluble fractions decreased for Fe, Pb, Zn, Ni, Cu, As and Hg, respectively and the major elements and components of HCO3, SO4, Ca, Na, Mg, Cl and K, respectively. Enrichment factors related to the relative abundance of the elements in crustal material were calculated using Fe as the reference. High enrichment factors (EFcrustal and EFplayawater) suggested that, in general, heavy metals had an anthropogenic origin and major ions had a natural origin. Factor analysis with varimax normalized rotation grouped the analyzed elements into four factors. Factor 1 indicated a high loading for positive nps-K, nps-Mg, nps-Ca, nps-Cl, nps-HCO3 and negative Cu, Ni, nps-SO4 components and represented the crust and anthropogenic origin. Factor 2 indicated a high loading of As and Zn. These metals are characteristics of anthropogenic origin. Factor 3 indicated an anthropogenic origin for Pb and Fe. Factor 4 indicated crustal source for Hg. Calcareous soils and alkalin soils in Arak plain are the sources of major elements and industrial activity and traffic are the sources of heavy metals in the rainwater samples in Arak city.