Analysis of Nitrates and Phosphates in Drinking Water Samples Collected from Tea Growing Community, Nandi Hills, Kenya

Abstract

Nitrates and phosphates are among the major inorganic pollutants in the environment, primarily contributed by nitrogenous and phosphate fertilizers, organic manures, human and animal wastes, and industrial effluents through biochemical activities of microorganisms. In Nandi Hills tea plantations, about 5,000 hectares of land are under mature tea and fertilizer is applied at a rate of 140 Kg /ha / year, with N: P: K being the commonly used fertilizer. Therefore, these inorganic ions can be discharged to water bodies through leaching and surface run-off. This study thus aimed at determining the concentration of nitrates and phosphate ions in borehole and stream water in Nandi Hills, Kenya. About 50 samples of drinking water (stream and borehole) were collected. The samples were analyzed to determine the concentration of nitrate ions, phosphate ions using cadmium reduction method and Uv-visible spectrophotometry. From the results obtained in the study, stream water recorded nitrate and phosphate concentrations of 2.91±0.74 and 0.30±0.08 mg/l respectively. In addition, there was a significant difference (P<0.05) in both nitrate and phosphate levels among the three sampling points in the three streams. However, there was no significant difference (P>0.05) in both nitrate and phosphate concentrations among the three streams used in the study. In borehole water, nitrate and phosphate levels were 1.69±0.79 and 0.29±0.07 mg/l respectively. Both nitrate and phosphate levels in stream and borehole water were found to be within the WHO acceptable limits. The study therefore concluded that concentrations of nitrate and phosphate ions in drinking water were within the WHO acceptable limits.