Lead and Cadmium Pollution in Urban Roadside Soil

Increasing urbanization and growing population density with their ensuing enhanced transportation cause problems in the bioconditions of the urban environment. Heavy metals such as lead and cadmium account for part of the environmental pollution resulting from urban transportation. The purpose of this study is to determine lead and cadmium concentrations and their distribution trend in urban roadside soil. For the purposes of this study, four roadside sites were selected in Isfahan. Samples were collected from surface soil (0-5 cm) and deep soil (50-55 cm) at distances 0.5 to 50 meters from the roads. The results from statistical analysis of lead and cadmium concentrations demonstrated that roadside soils were polluted with heavy metals as they exceeded maximum acceptable concentrations (MAC) of agricultural soils. It was observed that lead and cadmium concentrations in soil decreased nonlinearly with increased distance from road at each site. Regression analysis of data from lead and cadmium normalized concentrations (as the dependent variables) versus distance from road (as the independent variable) showed that the logarithmic regression model, in terms of its simplicity and its relative fitness to all the data from this study, could be adequately used as a suitable model for the distribution of these metals in roadside soils. The results obtained from this study can be used in designing urban areas and in planning urban transportation management and traffic control systems.