Seasonal variation of dissolved heavy metals in the reservoir of Shahid Rajaei dam, Sari, Iran

Abstract

Water temperature (T), electrical conductivity (EC), dissolved oxygen (DO), pH and concentrations of dissolved heavy metals (Ni, Co, Zn, Cd, Pb and Cu) were measured in the reservoir of Shahid Rajaei dam, north of Iran, during a year. Consequently, seasonal variations of the studied heavy metals and influence of the mentioned physicochemical parameters on concentration variations of the heavy metals were investigated. Significant variations were observed between the warm period (May–September) and the wet period (October–April), for the studied metals. The metals exhibited the following decreasing concentration order: Zn > Pb > Cd > Cu > Co > Ni and Zn > Pb > Cu > Cd > Ni > Co in warm and wet periods, respectively. The seasonal variations could be resulted from natural or anthropogenic sources and ambient conditions such as water temperature, EC, DO, pH, etc. Significant relationships were observed between concentration of some heavy metals and physicochemical parameters during warm and wet periods.

Keywords:

• Dissolved heavy metals
• Physicochemical parameters
• Seasonal variation
• Reservoir of Shahid Rajaei dam
• Iran

Acknowledgements

The authors express their sincere gratitude to the Environmental Science Laboratory in University of Zanjan, Iran, and they gratefully acknowledge Dr. Seyyed Aliasghar Arjmandi and Hossein Soltani for their contribution to this work.