Evaluation of heavy metals in water and sediments, pollution, and risk indices of Naltar Lakes, Pakistan

This study examined the physicochemical parameters of water and sediments in the Naltar Lakes, northern Pakistan. Water and sediments were sampled and analyzed for physicochemical parameters. Heavy metals such as iron (Fe, 11% and 12%), nickel (Ni, 100% and 88%), chromium (Cr, 22% and 12%), and arsenic (As, 0% and 12%) of sampling sites had surpassed the threshold of drinking water set by world health organization (WHO) in the Naltar Lake I (Naltar I) and Naltar Lake II (Naltar II), respectively. Water quality parameters were evaluated for the drinking and irrigation water quality indices (WQI). Drinking WQI values were found within the excellent category for Naltar I and Naltar II, except for the 6% of sampling sites observed in the good category. Toxic parameter concentrations were used for the risk indices, which revealed the highest average daily dose (ADD) values of 138 µg/kg-day and hazard quotient (HQ) 1.8 for children through nitrate (NO3) and As consumption in drinking water from the Naltar I and Naltar II, respectively. Water of the Naltar Lakes were characterized by rock weathering dominance. Heavy metal concentrations of sediments showed a moderate level of contamination that poses a low risk to the Naltar Lake ecosystem.