Assessment of heavy metals in Zohreh River, Iran

Zohreh River is one of the main water sources in south of Khuzestan, Iran. Due to importance of heavy metals on water quality, metal Index (MI), pollution Index (PI), heavy metal pollution index (HPI) and contamination index (Cd) were used to evaluate this River quality. For this purpose, water samples were collected during each season at 11 stations and seven heavy and trace metals [mercury (Hg), cadmium (Cd), chromium (Cr), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn)] determined. Standard value for each metal were extracted from international standards [United States Environmental Protection Agency (EPA) and World Health Organization (WHO)] and some national guidelines (Iran, Iraq, Egypt, Jordan, Lebanon and India). Results showed that Hg, Cd, Cr, and Zn concentrations were below the highest permissible value using all suggested guidelines while other metals showed low to high values based on used guidelines at some stations. MI was in the range of 1.01-2.88, 0.75-2.29 and 1.91-8.03 during spring, summer and winter, respectively. High values of PI (3.03), HPI (803) and Cd (2.03) were found during spring, winter and winter, respectively. The lowest values for mentioned indexes were found during spring (0.38), summer (75) and summer (-4.66), respectively. Comparison between selected indexes indicated that MI index showed normal values compared with other indexes. Also the guideline suggested by Lebanon revealed high quality for the River compared with other standards. Consequently, Zohreh River showed low quality for drinking uses during winter while the River showed high quality during other seasons.