Lead and Cadmium Distribution in Urban Roadside Soils of Isfahan Iran

Soil Sample were collected from four sites in the urban roadsides of Isfahan , Iran. At each site , samples were collected at distance of 0.5, 1, 2, 3, 4, 5, 6, 7, 7, 8, 10, 15, 20, 30, 40, 50m from road curbs and at depths of 0-5 and 50-55 and 50-55cm.. Samples were extracted by concentrated nitric and hydrofluoric acids and total concentrations of cadmium and lead values were obtained by Flam Atomic Absorption Spectrophotometer (FAAS). Observed results showed that traffic emissions were the main source of the pollution. Roads were categorized into the high and low traffic volumes. The average concentrations of pb and Cd were 126.82 and 2.41 mg/kg soil , and for sites with high traffic volume were 183 and 2.57 mg/kg soil and for sites with low traffic volume were 70.64 and 2.25 mg/kg respectively. Pb concentrations declined rapidly by increasing distance from roads. With increase in soil depth, the concentrations decreased but the trend of decreasing is completely different from what was imagined and high levels of pb were observed in depths. Although cadmium values were near to background level, it showed a similar trend like what was seen about pb concentrations . So it needs to study more about interaction of urban traffic and capability of its polluting the environment.

کلیدواژه ها:

Traffic emission ، Distribution ، Roadside soil pollution