Excessive accumulation of nitrate and nitrite is a major cause of water pollution, air pollution and various health hazards. Hence, it is important to know the amount of these anions in environmental samples. In this study, the levels of nitrate and nitrite were investigated in soil and water in Adami Tulu Judo Kombolicha District, Oromia, Ethiopia. Levels of the anions were determined by UV-Visible spectrophotometer. Nitrite was determined by forming a violet azo dye while nitrate was determined indirectly by forming yellow sodium nitrophenoxide. Different analytical parameters were optimized for stable color formation prior to analysis of nitrate and nitrite in water and soil samples. The results of the study showed that nitrite content in water and soil samples ranged from (1.02± 0.06) – (1.33 ± 0.08) mg/L and (0.58 ± 0.022) – (0.95 ± 0.026) mg/kg respectively. Nitrate content also ranged from (56.49 ± 1.63) – (75.5 ± 4.73) mg/L and (138.17 ± 5.61)–(169.5 ± 19.62) mg/kg for water and soil samples respectively. The concentrations of nitrite in water samples were within the safe limit of USEPA and WHO. The level of nitrate in water samples was below the limit set by WHO. The water in the area was suitable for agricultural and drinking purposes from the perspective of the levels of nitrite and nitrate.

Keywords: nitrite, nitrate, soil, water, UV-Visible spectrophotometer