Determination of metals in water samples within the irrigation area in Telo District, Kaffa Zone, South Western Ethiopia

Abstract

Water contamination due to the accumulation of metal is not only an environmental problem, but it is also a global issue. The river flows alongside the town in its downward direction, where runoff from the uplands and municipal trash discharge during floods may contribute to the contamination of the river. Despite the fact that this river is the area's primary source of water, the water near the effluent release point is extremely corrosive. The nearby settlements depend on this untreated river water for drinking, irrigation, and other domestic uses since they have no access to a municipal water supply. The aim of the present study was to evaluate the degree of metal contamination in the Obasho river water samples collected from irrigation water sites in the Gurguba region. Three samples were collected from each of four irrigation water sites, which were 1.5 km away from each other. A total of 12 water samples were collected by following the standard water sample collection protocol. 100 mL of the irrigation water sample was digested in aquaragia, and AAS was used to determine the concentration of metals in the water samples. The concentration ranges of some metals were: Ca (1.84387–2.810824 mg/L), and its maximum limit in FAO is 20.0 mg/L; Mg (3.176942–4.543031 mg/L), and its maximum limit in FAO is 5.0 mg/L; Cr (0.039227–0.047872 mg/L), and its WHO/FAO permissible level is 0.1 mg/L; Co (0.036703–0.057218 mg/L), and its permissibility level is 0.05 mg/L WHO/FAO, Cd (0.006198–0.02856 mg/L), whose maximum limit in FAO is 0.01 mg/L, and Pb (0.065138–0.091131 mg/L) WHO/FAO permissible level is 5.0 mg/L. The mean concentrations of metals (Ca, Mg, Co, Cd, Pb, and Cr) in all study sites were below the regulatory limits except for Co and Cd; no water contamination was caused by these metals at the study sites. However, the mean concentration levels of Co in all study sites were above regulatory limits. The mean concentration of Co at Konit Kochito and Cd at Geremew Mamo, Konit Kochito, and Gereno Gebito is also greater than regulatory limits. A pair-wise comparison of some metals in study sites was carried out, thus the mean concentration of the irrigation water sites sample was significantly different from some metal concentration (p < 0.05) at the 95% confidence level. Generally, there was no cumulative effect of water contamination caused by Ca, Mg, Co, Cd, Pb, and Cr in Gurguba Kebele study sites, and it may not appear to pose very serious environmental problems at this moment. Thus, determining the metal content in irrigation water samples is crucial for ensuring the safety and sustainability of agricultural practices. It raises awareness regarding the contents of heavy metal contamination and sets limits for acceptable metal concentrations. It has also vital role in maintaining soil health.