Assessment of spatial distribution pattern of heavy metals surrounding a lead and zinc production plant in Zanjan Province, Iran

Abstract

The present study aimed at characterizing the spatial distributions and investigating the contents of six heavy metals (Co, Ni, Cu, Zn, Cd and Pb) in top soils, surrounding the National Iranian Lead and Zinc Company (NILZ) in Bonab Industrial Estate (Zanjan-Iran) by Geostatistical analyst and Moran's I autocorrelation index. The soil samples (126) were collected from the area with a radius of 5km of the NILZ Company. The average amount of Co, Ni, Cu, Zn, Cd and Pb metals were 4.16mgkg−1, 26.38mgkg−1, 18.31mgkg−1, 684.11mgkg−1, 5.79mgkg−1, and 119.59mgkg−1, respectively. Principal Components Analysis (PCA) classified the investigated heavy metals in two groups. These groups were Factor I (Pb and Cu) and Factor II (Co, Ni, Zn and Cd) that confirm exist the anthropogenic source of the pollutants. Moran's I autocorrelation index was cleared that the high–high spatial clusters of topsoils contaminated with heavy metal were located in the center of study area, near NILZ Company. It was deduced that the company activities have a big impact on distribution of heavy metal in study area. Geostatistical analysis revealed that the high values of all studied heavy metals were located near the NILZ Company. According to comparison the prepared and land use maps, it was cleared that pesticides and chemical fertilizers, geochemistry and anthropogenic sources are the main factors in spatial variation of heavy metals.