Lead Contamination and Pollution Indexes in Roadside Soil in Tehran, Iran

Background and purpose: In the process of rapid urbanization and industrialization in developing countries, environmental pollution is a major concern. One of the fastest growing problems of environmental pollution is an excessive intake of lead in urban soils. Lead concentrations in urban soil may result from human activities such as vehicle emissions and industrial activities. This study aimed to determine of lead contents in roadside soil samples in Tehran city, Iran. Materials and Methods: One of Tehran municipality’s subsections was selected for the collection of 21 samples from seven stations along a main urban highway. In this study, samples were taken over a period of 3-month in the dry season. Sampling was performed in the order of 100 m long, perpendicular to the roadside at 0, 50, and 100 m from the road. Lab measurements were performed on the physical and chemical properties of samples. The extraction was performed using four kinds of acids (HCL, HNO3, HF, and HCLO4). Results: Lead concentrations were measured by a spectrophotometer with an average concentration of lead in soil samples of roadsides standing at 112.21 part a million (PPM), and the average lead bio-accessibility at 14.19 PPM.  Conclusion: Lead concentrations showed a linear decrement in proportion to the distance from center line of the road. Human cultural activities were sources of lead pollution by examine soil contamination indexes.