Investigation of Quantitative Status and Pollution Indices of Some Pollutants in Surface Soils as Affected by Tailings Dam (Case study: Chahar Gonbad copper mine)

Mine tailings dams, as one of the important and unavoidable parts of any mine, are considered as a sources of environmental pollution in the areas adjacent to each mine, which has received less attention from an environmental point of view. The present study was conducted to investigate the environmental effects of the tailings dam of Chahar Gonbad copper mine on changes in quantities of some soil pollutants adjacent to the tailings dam of this mine. In this study, according to the location of the region, six samples of sediment from the tailing dam and nine samples of topsoil were collected and the amounts of Pb, Sb, Zn, Cd, As and Cu; as well as soil pollution indices of each element (enrichment factor (EF), Geo-accumulation factor (Igeo), and contamination factor (CF)) were measured and compared with the environmental protection standard. The results of pollutants in sediments showed significant enrichment of Cu and Sb elements in tailings dam sediment samples. Based on the standard values ​​of soil pollution, with the exception of high levels of Cu (38-135 mg kg-1) and As (7.2-17.8 mg kg-1) in some samples, the observed levels of Pb, Zn, Cd and Sb in all soil samples were lower than the environmental protection standards. According to the results of soil pollution indices, the two elements Sb and As had higher EF and Igeo than the other elements, which shows the effect of anthropogenic factors (tailings dam) on amounts of these elements. The results of this study showed, despite the high amounts of Cu in the soil surface samples (due to the nature of the Cu vein deposit in the region), the area adjacent to the dam is not contaminated with other pollutants, although EF of As (4-15.3) and Sb (3-5.9) can be a serious alarm to pollute the area with these elements in the coming years. Based on the obtained results, it is suggested that changes in the pollution of tailings dams as one of the sources of environmental pollution in the areas adjacent to the mines, be continuously assessed and appropriate management measures be applied.