Study of Heavy Metals in the Atmospheric Deposition in Zanjan, Iran

Backgrounds and Heavy metals in dust can enter to the human body through ingestion andinhalation. They can pollute the water and soil resources via atmospheric precipitation and accumulate in the plants tissue and enter human body by water and food. The aim of this study was measurement of the heavy metals in wet and dry atmospheric precipitation and effects of pollution sources at the ground surface on the concentration of heavy metals in the atmospheric precipitations. In this study the zanjan city was divided into 5 zones and wet and dry precipitations were collected in autumn, winter and spring (2008- 2009) from zones. The concentrations of Pb, Cd, Cr and Zn the collected precipitations were determined by Atomic Absorption spectroscopy method. The averages of concentrations of Pb, Cd, Cr and Zn were 0.082, 0.286, 0.018, and 0.009 (mg/m 2.d)respectively. The correlation coefficients between Pb-Zn was 0.8 (P<0.01) and for Cr-Cd, Cd-Pb, and Cr-Pb were 0.89, 0.58 and 0.61 respectively. The results showed that the industrial sources of heavy metals play the main role in concentration of heavy metals in wet and dry atmospheric precipitation in Zanjan.The correlation coefficients showed that the lead and zinc result from a common source. This source can be the lead and zinc factories locating around the city. The measurement of heavy metals in atmospheric precipitation shows the effects of anthropogenic sources in air quality. The heavy metals concentration in atmospheric precipitation can be use as air pollution index.