Assessment of trace elements concentration in soils of the Hashtgerd Area using geochemical and multivariate statistical methods, Alborz province, Iran

Concentrations of trace elements have been studied in 160 soil samples in the Hashtgerd area. The average abundance of trace element contents in soil samples follow the order of: V>Zn>Cu>Ni>Cr>Pb>Co>As>Mo in agricultural and V>Zn>Cr>Ni>Cu>Pb>Co>As>Mo in non-agricultural soils. Comparison of mean concentration of the trace elements in the soil samples with mean worldwide values reveals higher As، Co، Cu، Ni، V and Zn contents، and lower Cr، Mo and Pb contents in this area which is somewhat different in abundance in various soil uses. The results of contamination factor (CF) by using mean worldwide soils for agricultural and non-agricultural soils reveal that As، Co، Ni، Zn and V have moderate and Cu has considerable contamination factor. The application of modified degree of contamination (mCd) based on background and mean worldwide values indicate very low and low degree of contamination in soil samples of Hashtgerd area. The results of enrichment factor show that Cu، Zn، Pb and V in agricultural soils and Cr and Zn in non-agricultural soils are enriched compared to the average abundances of background level. The principal component analysis (PCA) was used to assess the association of elements. The strong association of elements such as Co، Fe، Ni، and Cr in agricultural soils and Cu، V، Co، Fe، Co and Ni in non-agricultural soils suggests a common source، i. e. derivation from parent rock units. Cu، V and Zn display a quasi-independent behavior within the groups that show geogenic and anthropogenic sources. The variable behavior of Pb، and As probably reflect various sources of these elements. In addition، Significant and moderate positive correlation of trace elements such as Cr (agricultural soils)، Ni، Co، Cu، Zn and V with Fe content indicate the strong affinity of these elements for Fe oxide in soil samples.