Contamination Level, Source Identification And Health Risk Assessment of Potentially Toxic Elements In Drinking Water Sources of Mining And Non-Mining Areas of Khyber Pakhtunkhwa, Pakistan

Abstract

Accelerated mining activities have increased water contamination with potentially toxic elements (PTEs) and their associated human health risk in developing countries. The current study investigated the distribution of PTEs, their potential sources and health risk assessment in both ground and surface water sources in mining and non–mining areas of Khyber Pakhtunkhwa, Pakistan. Water samples (n=150) were taken from selected sites and were analyzed for six PTEs (Ni, Cr, Zn, Cu, Pb and Mn). Among PTEs, Cr showed high mean concentration (497) μg L–1, followed by Zn (414) μg L–1 in mining area, while Zn showed lowest mean value (4.44) μg L–1 in non-mining areas. Elevated concentrations of Ni, Cr and moderate level of Pb in ground and surface water of Mohmand District exceeded the permissible limits set by WHO (2017). Multivariate statistical analyses showed that pollution sources of PTEs were mainly from mafic-ultramafic rocks, acid mine drainage, open dumping of mine-wastes and mine tailings. The hazard quotient (HQ) was highest for children relatively to adults, but not higher than the US-EPA limits. The hazard index (HI) for ingestions of all selected PTEs were lower than the threshold value (HIing <1), except Mohmand District which showed (HI >1) in mining areas through ingestion. Moreover, the carcinogenic risk (CR) values exceeded the threshold limits for Ni and Cr set by the US-EPA (1.0E−04 to 1.0E−06). In order to protect the drinking water sources of the study areas from more contamination, the management techniques and policy for mining operations need to be implemented.