Heavy Metal Contamination and Distribution in the Shiraz Industrial Complex Zone Soil, South Shiraz, Iran

Concentrations of heavy metals (As, Co, Cu, Ni, Mo, Pb and Zn) are studied in the soil of Shiraz industrial complex zone, south Shiraz, Iran to asses metal contamination due to industrialization, urbanization and agricultural activity. Soil samples were collected from three different depths. The A and C depths are enriched with metals such as Ni, As, Mo, Cu, Pb and Zn, compared with the B depth. The average abundance order of heavy metal contents in soil depth are: Ni>Zn>Cu>Co>Pb>As>Mo. Soil contamination is assessed on the basis of contamination factor (CF) and modified degree of contamination (mC ). The CF and mC base of d d background values in the three sampled depths for Cu, Zn, Co, Ni, Mo and As are moderate. Pb reveals considerable contamination. The results of enrichment factor (EF) show that using Sc concentration in the average shale produces higher average EF values for Ni, Co and Mo as compared to average values determined using the actual Sc content in lower core baseline values (background). The results of the principal component analysis (PCA) show Zn, Co, Ni, Sc, Cu, Al and Fe come from a similar source and are not influenced by anthropogenic sources. High loading of Zn, Co, Cu and Ni with clay, Al and Fe indicate the active role played by Al and Fe hydroxides and clay content on distribution and sorption of the studied heavy metals in soil. Also, PCA results indicate that As, Mo and Pb behave differently at different depths.