Potential risk assessment of heavy metals in the Aharchai River in northwestern Iran

The pollution of water sources by factories that discharge heavy metals into the environment is among the most dangerous threats to human health and the environment. This study investigated the concentration of heavy metals (Pb, Cd, Fe, Cu, Cr, and Zn) in the Aharchai River as the most important river in northwestern Iran. This study had a descriptive cross-sectional design, and sampling was done at six hydrometric (gauging) stations along the river during the rainy (spring) and dry (summer) seasons in 2018. The concentrations of heavy metals were measured by an atomic absorption device. The results showed significant differences in the concentrations of heavy metals at various stations in the two seasons of spring and summer. As for the concentrations of Pb and Cd, all stations stood higher than the standards introduced by the World Health Organization (WHO) for drinking water. The results of potential risk assessment revealed that risk quotient (RQ) for Cd and Pb were 2.1 and o.61, respectively, indicating a small potential for adverse effects related to the Cd element in the Aharchai River. Therefore, it can be concluded that the Aharchai River is in unfavorable condition regarding aquatic life, especially in the downstream area and in some routes in terms of agricultural purposes.