Study of lead, nickel and zinc heavy metals concentration in muscle, liver, gill, and kidney of Caspian kutum (Rutilus frisii kutum) in Guilan and Mazandaran provinces

Heavy metals from different sources are continuously introduced into aquatic ecosystems and with a view to reinforcing each other's impacts are a serious threat to aquatic life and ultimately to human society. The aim of this study was to determine the concentration of nickel, lead and zinc in Caspian kutum tissues in Guilan and Mazandaran provinces and also to compare it with world standards. Sampling was done in spring 2017 from Sefidroud and Shirood rivers. Samples were prepared by acid digestion method. The concentration of nickel, lead and zinc in some tissues was measured by ICP-OES and compared with some standards. The nickel value recorded in most tissues was significantly higher than the standards presented. The high concentration of nickel in Caspian kutum in Guilan is probably due to drainage of more effluents containing this metal in Guilan province and transfer of pollutants from oil and shipping activities of Azerbaijan by dominant marine currents to the coast. Due to the high concentration of nickel and the high catch of Caspian kutum from the north of the country, as well as the direct effect of heavy metals on each other, more care should be taken when feeding this fish.