Occurrences and Ecotoxicological Risk Assessment of Heavy Metals in Surface Sediments from Awash River Basin, Ethiopia

Like many areas in developing nations, rapid population growth, a high urbanization rate, and poor waste management practices have been observed in the Awash River Basin. Moreover, no comprehensive study has been conducted in this basin to evaluate sediment contamination with heavy metals. About 46 sampling locations were considered to study heavy metal concentrations, distributions, pollution levels, and potential ecological risks associated with these contaminants. The results indicate that average concentrations of all metals have exceeded their respective background values except Pb and Hg. A comparison with similar studies also revealed that sediments from the Awash River Basin had a high average value for Cd. The mean enrichment values of heavy metals increased in the order of Hg < As < Pb < Ni < Cu < Cr < Zn < Cd. Multivariate analysis revealed that Ni and Cu had common sources. The average potential ecological risk index (ERI = 355.54) indicates high potential toxicity response in the study area. In general, surficial sediment contamination with heavy metals is causing high ecological hazards in Awash River Basin. This study sheds lights on the current level of contamination of heavy metals which are widely distributed across the sediments of rivers and streams of Awash River Basin.