Environmental geochemistry, source, and health risk assessment of the potentially toxic elements in the urban soils of Shahrood, Semnan Province

The present study aims to investigate the environmental geochemistry, source, and health risk of potentially toxic elements in urban soils of Shahrood, Semnan Province. For this purpose, the total concentration of major and trace elements in 26 topsoil samples was determined using an ICP-MS device. The average concentrations of As, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb and Zn are 7.9, 0.1, 7.4, 77.5, 59.8, 448.9, 0.8, 31.5, 35.7 and 104.1 mg/kg, respectively. On the basis of the geochemical indices (i.e., enrichment factor, geoaccumulation index, single-factor analysis, nemerow integrated pollution index, and potential ecological risk index), the studied soils are polluted with potentially toxic elements, especially As, Pb and Cu, and the most polluted sites are located in the northern parts of the city. Statistical analyses (cluster analysis and principle component analysis) indicate that Co and Mn are mainly from natural sources, while Cr, Mo, Ni, Zn, Cu, As, Cd and Pb are probably from anthropogenic sources (especially industrial inputs and traffic). The health risk assessment shows that there is a non-carcinogenic risk of Pb for children through the ingestion route. The carcinogenic risk of As, Cr and Ni for children through the ingestion route is higher than the reference value (1×10-4). In conclusion, the pollution of the studied soils with As, Pb, Cu, Cr and Ni must be considered as a concern in the study area.