Dissolved Heavy Metals in the Reservoir of Shahid Rajaei Dam, Sari, Iran

Concentrations of heavy metals (Ni, Co, Zn, Cd, Pb and Cu) in the reservoir of Shahid Rajaei Dam, one of the main water reservoirs in north part of Iran, were determined using a differential pulse polarography (Metrohm 797 VA) and compared with the national and international specified maximum contaminant levels (MCL) for different purposes of water use. The results showed that concentrations of Cd and Pb in the reservoir exceeded different MCLs and thus they could pose health problems for regional residents. Averaged concentrations of heavy metals exhibited a decreasing order of: Zn>Pb>Cd>Cu>Ni>Co. The spatial distribution and seasonal variation implied the significant effect of anthropogenic sources on concentration of heavy metals. These metals mainly originate from the fertilizers and pesticides which are used in upstream farm lands of the flood plain; however the natural sources should not be neglected. The results would help in water resource management of Shahid Rajaei Dam.