Assessment of heavy metals contamination in urban topsoil from Arak industrial City, Iran

An increase in heavy metal pollution in the soils of Arak due to industrialization and urbanization has become an environmental problem. The region hosts several industrial facilities which are the main source for hazardous wastes which include electric, metal, automotive supply industry, food, machinery, and chemicals. Soil samples were collected from these industrial areas in the central and around of Arak city and analyzed for their metal contents. Results of the analysis show that the soils are characterized by high concentrations of Ni and Cu. Concentrations of As, Pb, Zn, Cr and Co elements do not exceed the permissible levels in the most of the samples. Concentrations are 3.01- 17.36 mg/kg of Pb, 9.60-195.55 mg/kg of Cu, 12.20- 63.12 mg/kg of Ni, 0.85- 69.91 mg/kg of Zn, 1.41- 4.50 mg/kg of As, 25- 130 mg/kg of Cr and 7.54- 24 mg/kg of Co. Application of factor, cluster and correlation analysis showed that heavy metal contamination in soils originates from industrial activities and heavy traffic which are of anthropogenic origin. Contaminations in soils were classified as geoaccumulation index, enrichment factor, contamination factor, and contamination degree. Contamination degree values indicate that heavy metal pollution levels of soils collected from industrialization sites are greater than those of distal parts of industrialization. Spreading of hazardous wastes from industrial facilities in the study area via rain or wind is the main source of soil pollution. In addition, agricultural wastes and traffic-related metal pollution is also observed.