Pollution Level of Heavy Metals and Risk Implications from the Lower Omo River: East African Fresh Water in the Semiarid Region of Southern Ethiopia

Abstract

The Omo River passes through Omorate town, where domestic, municipal, and industrial waste from the town and its vicinities, including agrochemicals, flows into the river.Hence, this research aims to assess heavy metal contamination levels and associated risks in the Lower Omo River, located in the semiarid region of Southern Africa. The mean concentrations of the detected heavy metals in the river water were 0.439mg/L for (Mn), 0.1 (Zn), 0.168 (Cu), 0.393 (Cr), 0.318 (Pb), 0.007 (Ni), 8.926 (Fe), and0.06 (Co).The order for the mean concentrations of the heavy metals in the water was Fe >Mn > Cr > Pb > Cu > Zn > Cu > Co > Ni. The mean levels of lead (Pb), manganese (Mn), and chromium (Cr) were above the acceptable limits for water set by WHO. The HPI value indicates that all water sample sites were heavily polluted. The HQs through oral ingestion and dermal for both children and adults were in the order of Cr >Pb> Mn > Fe >Cu > Co > Ni > Zn. The HQ value greater than 1 was examined for Cr, Pb, and Mn both in children and adults through ingestion and dermal route from the River water.The CRs for both children and adults via ingestion of the River water followed the order Cr > Pb. According to CRI value, the River water could be classified as very high environmental risk.

Keywords

• Ecological risk; human health risk; heavy metals; Omo River