Geoenvironmental studies and heavy metal mapping in soil: the case of Ghohroud area, Iran

Geological features play a key role in determining variations in elemental concentrations in an area. Among different geological phenomena, intrusion of igneous bodies and associated alteration contribute significantly to the introduction of heavy metals into the area. This study has focused on Ghohroud, in central Iran, which is situated in the Urmieh–Dokhtar magmatic arc (UMDA) belt, and magmatism has developed as a result of the intrusion of a granodiorite body. The area has later been affected by hydrothermal fluids, resulting in argillic and propylitic alteration and contact metamorphism. The objectives of this study were to assess the degree of contamination and to describe the surface soil geochemical variations in relation to the geology, lithology, and hydrothermal activity in the Ghohroud area. Soil sampling was used for the geochemical study, and 96 samples were collected and analyzed by ICP-OES. Among the analyzed elements, the concentrations obtained for Pb, Zn, Ni, Cu, As, Co, V, and Mo were selected for statistical treatment. Different geoenvironmental indices were calculated, and the results showed that Cu, Mo, Pb, and Zn were present at a contaminating concentration. Remote sensing studies were employed in this study for alteration mapping. It was concluded that the development of different alteration types and proximity to intrusive bodies were the main contributors to the increased heavy metal concentrations in the area.