Trace metal element pollution in media from the abandoned Pb and Zn mine of Lakhouat, Northern Tunisia

Abstract

This study aimed to determine the contamination status, dispersion mechanisms, and ecological and health risks associated with trace elements in environmental media collected from the abandoned lead and zinc mine of Lakhouat, Northern Tunisia. A total of 41 samples, including 3 mine tailings, 21 stream sediments and 17 soils were collected and analysed for some potentially toxic elements (As, Pb, Hg, Cd, Cr, Co, Ni, Cu, Zn and Zr). Among 10 potentially toxic elements that were analysed, As, Cd, Hg, Pb and Zn exhibited considerably high concentrations in mine tailings and stream sediments. The Spearman rho correlation coefficient and principal component analysis showed that mining activities mainly controlled As, Cd, Hg, Pb and Zn. At the same time, natural sources strongly governed Co, Cr, Cu, Ni and Zr. Pollution indices revealed a very contaminated area with an essential risk to ecosystems and human health. Ecological risk assessment suggested that the potentially toxic elements in mine tailings and stream sediments induced significant ecological risks, mainly mediated by Cd. The health risk assessment revealed that oral ingestion was the primary exposure pathway to potentially toxic elements in the stream sediments and mine tailings, and children were more susceptible to adverse health effects. Pb and As had high non-carcinogenic risks for an individual potentially toxic element, and Cd and As presented intolerable carcinogenic risks. Overall, the results indicated the need for epidemiological studies to outline the extent of the occurrence of diseases related to mining activities in the region.