Spatial Variability of Nitrate Levels in Groundwater of Lokoja Town, Kogi State, Nigeria

Abstract

This research was undertaken to assess the spatial distribution of Nitrate levels in the groundwater withdrawn via boreholes. This was done by sampling functional boreholes in the study area for nitrate levels. Lokoja town was selected for this research and the analysis of nitrate contamination was conducted in September which is usually the peak of the rainy season. Ten (10) water samples were collected from ten (10) different boreholes across Lokoja town and examined for Nitrate contamination. Laboratory analysis was conducted via standard methods for water examination using the Cadmium Reduction Method. Results from the laboratory analysis showed that all the boreholes sampled during the study were contaminated with Nitrate. However, the levels of contamination observed were all below the maximum limit of 50 milligrams per litre (mg/l), prescribed by the Nigerian Standard for Drinking Water Quality (NSDWQ). Nitrate levels observed were low at the northern part of the study area and increased down south. This can be attributed to factors of land use and hydrogeologic features of the place. Annual flooding, the use of inorganic fertilizers and the indiscriminate dumping of waste might be responsible for the high levels of Nitrate observed in Ganaja Village, which is in the southern part of the study area. On a whole, it is recommended that further work be carried out to examine Nitrate levels in the groundwater of other flood plains within the country with similar land use patterns. This will help to ascertain the combined influence of waste, the use of inorganic fertilizers and flooded soils on nitrate levels in groundwater reserves. Furthermore, the water in the study area can be utilised if properly subjected to efficient purification methods.