Heavy Metals Contamination in Soil, Surface Water and Groundwater of an Agricultural Area Adjacent to Tehran oil Refinery, Iran

Abstract

Concentrations of six heavy metals including Cr, Mn, Ni, Pb, V and Zn were determined in topsoil (from 47 grid cells), surface water (4 streams) and groundwater (8 wells and 4 qanats) from an agriculturalarea located at south part of the Iranian capital, near the Tehran oil refinery. Concentrations of the elementswere measured using flame and flameless atomic absorption spectrometry. Based on the results of agglomerativehierarchical method for clustering of the soil grid cells, some similarities between the dendrograms of Mn andNi, Pb and V, and Zn and Cr were observed. The pattern of metal occurrence exhibited the following descendingorder: Mn> Zn > Cr > V > Ni > Pb for soil, Pb, Ni, Mn > Zn, V, Cr for wells and Ni, Pb > Cr, V > Mn, Zn forstreams. Significant positive correlations were found among Zn, Cr and Ni as well as between Mn and Zn, Niand V, and Pb and Zn in soil. Significant positive associations were also observed in the case of Mn-Ni and Mn-Cr in wells and streams, respectively. The mean concentrations of the heavy metals in the soil exceeded thenormal uncontaminated soils (with the exception of V). In the case of Cr, Zn and V, our results were above thesoil critical range. The mean levels of all the elements in the surface and groundwater were considerably lowerthan the related guidelines and limits.