Heavy Metals Contamination and Distribution in Drinking Water from Urban Area of Mashhad City in Northeast Iran: Implications for Water Quality Assessment

The fast industrialization and urbanization in the world have led to increasing heavy metal pollution in the water supplies. Here, we examined the spatial and temporal distribution and contamination of heavy metals and physicochemical parameters in the drinking water sources of Mashhad in Iran. In this survey, 432 samples of drinking water were collected from 5 zones and 36 stations from August 2017 to May 2018. The results of heavy metal measurements showed that the average concentrations of arsenic (As), mercury (Hg), chrome (Cr), nickel (Ni) and Pb were 0.198±0.11, 0.018±0.04, 5.80±7.87, 1.695±2.16 and 0.574± 0.22 μg L^-1 for arsenic (As), mercury (Hg), chrome (Cr), nickel (Ni) and Pb, respectively. This result showed that the concentration of heavy metals and physicochemical parameters were comparatively lower than the threshold values throughout the study period; however, some stations showed metrics values above the acceptable limit. Thus, there is still potential contamination in drinking water due to potential heavy metal interactions and long-term exposure. Results of this study showed the current pollution status of drinking water in Mashhad needs remediation efforts to protect human health in urban regions, which highlighted a basis for decision-making in the future to take the main action on contamination control.