Assessment of the Distribution and their Health Risk of Trace Metals in Tsaeda Agam River, Mekelle City, Tigray, Northern Ethiopia

Abstract

The study was conducted to assess the contamination of Tsada Agam River by trace metals. Trace metals were found in water samples in the following concentrations (in mg/L): Co, 0.02-0.03; Pb, 0.01-0.06; Zn, 0.21-0.50; Fe, 0.30- 5.18; Mn, 0.10-0.15; Cu, 0.015-0.018 and Cd, 0.01-0.015. Trace metals were also found in soil samples (in mg/kg): Cu, 34.50-36.83; Pb, 1.17-3.42; Co, 29.75-31.53; Ni, 12.42-26.30; Mn, 616.06-811.30; Cr, 37.01-42.92; Cd, 13.87-14.55; Fe, 33563.53-3696 and Zn, 283.50-495.33. In vegetable samples the levels of trace metals were (in mg/kg): Cu, 3.00- 14.67; Co, 9.33-38.31; Ni, 0.29-1.78; Mn, 30.93-346.90; Zn, 15.67-285.67; Pb, 0.14-2.67; Cd, 3.79-11.01; Fe, 46.67- 730.00 and Cr, 2.53-5.72. Cadmium in water samples was beyond the limits of WHO/FAO for drinking and irrigation; Cd, Fe and Zn in soil samples was above the limits of Ewers and Zn, Pb, Cd, Fe and Cr concentrations in vegetables were above the limits given by Weigert. The calculated HRI values for Cd (Site-2 and 3) and Mn (site-1 and 3) were 1.4 and 1.7 and 2.0 and 3.78, respectively, indicating a health risk of Cd and Mn exposure. Therefore, regular monitoring of trace metals is essential to prevent excessive build-up in the food chain and to protect public health.