Aquatic Ecosystems and Environmental Management Water Quality of Akaki Rivers and Its Impact on Irrigated Vegetable Farms

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Addis Ababa University


Urbanization, industrialization and agricultural development practices are the main causes for the environmental degradation of surface waters including rivers. The highly impacted Akaki River, the subject of the present study, is being used for irrigation, watering livestock, sanitation and other domestic purposes. This represents a serious threat to public health and life of aquatic and terrestrial organisms. Thus, with the view of gathering information usable in the development of strategies of protection of this aquatic resource, physico-chemical and microbial water quality parameters of the irrigation water, irrigated soils and leafy vegetables cultivated on them were assessed from March to August, 2017. The biotic transfer factor (TF) and Target Health Quotient (THQ) for all measured metals were also calculated. The observed levels of Turbidity, TSS, TDS, TP, and Nitrite surpassed the acceptable levels set for domestic use and general water quality assessment criteria. DO and BOD5 levels also failed to comply with the safe limits set for aquatic life and general water quality assessment criteria. The levels of Faecal coliforms, Fe, Mn, Cu, Zn and Cr surpassed the maximum levels recommended for the safe use of wastewater for irrigation of vegetables. Vegetable farms in and around Addis Ababa, which were irrigated with the polluted waters of Akaki River exhibited concentrations of Zn, Cr, Cd and Cu in the soils of farm plots and of Fe, Zn, Cr, Ni, and Pb in vegetables grown on them that surpassed the safe limits recommended by international organizations. The potential health risk indicator (THQ) for Fe, Mn, Pb and Cd also reached values above 1, suggesting that they may pose health effect on consumers. The present findings suggest the need for immediate measures to protect consumers and the aquatic resource.



Akaki River, Faecal Coliforms, Heavy Metal, Nutrients, Soil, Total Coliforms, Vegetable, Waste Water