To determine the origin of heavy metals, and hence the risk assessment of natural and anthropic pollution, the effects of parent materials, soil genesis, and human activities on the content and distribution of Cd, Cu, Mn, Ni, Pb, Zn and Fe in soils near Mofateh powerhouse of Hamedan, Iran, were assessed. The potential industrial sources of pollution in this area are Mofatteh powerhouse and a metal smelter plant which have started their activities since 1995 and 2003, respectively. Six types of parent materials including shale, schist, limestone, alluvial plain, alluvial terraces and fan deposits were identified and soil genesis and development were studied in each of them. Total content of selected metals were determined in parent materials and pedogenic soil horizons. The concentration of metals in four different chemical phases, including acetic acid extractable, reducible, oxidizable and residual fractions, was determined with four-step sequential extraction procedure (BCR). Soil development is limited in the studied region so that the discrepancy between solum and parent material in terms of heavy metal content is not great in general. The highest amount of Zn, Cu and Ni was observed in Shale soils (136.0, 31.3 and 57.7 mg/kg, respectively); accordingly, the highest concentration of these metals was also measured in the shale parent material (121.1, 37.1 and 53.5 mg/ kg, respectively). Limestone soils have the lowest amount of Cd, Cu, Mn, Ni, Zn, Pb and Fe compared to the soils developed from other parent material. The lowest amount of Cu, Mn, Ni, Zn and Fe was also measured in limstone (7.0, 35.0, 10.9, 8.5 and 4000 mg/kg, respectively). Independent of soil types and parent materials, most of the metals, except Mn, were present in the residual fraction. The concentration of Mn in all profiles is highest in reducible fraction. Low degree of soil development and the prevalent presence of metals in residual fraction show the influential role of parent materials in
