Environmental geochemistry of potentially toxic elements in tailing of the Ahangaran Pb-Zn mine, Hamadan province

The present study aims to investigate the environmental geochemistry of potentially toxic elements (PTEs) in tailing samples of the Ahangaran Pb-Zn mine, located 95 km southeast of Hamadan. For this purpose, physico-chemical properties of 14 tailing samples, mineralogy and the concentration of PTEs were studied. The values of pH, carbonate content, and cation exchange capacity (CEC) ranged between 7.7-9.4, 50.5-64.5 %, and 27.3-35.1 meq/100g, respectively. The main clay mineral detected in the studied samples was montmorillonite; quartz and siderite were the most frequent mineral phases in the samples. The tailing samples, based on the total concentration of potentially toxic elements and the calculation of environmental indices, were enriched in Pb, Zn, Cd, As and Ag, and were of high ecological risk. Human Health Risk Assessment (HHRA) revealed that the hazard quotient of PTEs was much higher for children than adults. The highest values of non-carcinogenic risks via ingestion, dermal contact and inhalation were obtained for As, Mn, and Cd, respectively. The ingestion of As, Cd, and Cr for children, and the ingestion of Cd for adults are associated with probable carcinogenic risks. Based on the obtained results, disposed tailings around the Ahangaran mine can be considered a potential source to pollute the groundwater resources and agricultural soils. Therefore, appropriate environmental management of waste disposal as well as taking remediation actions deem necessary.