Spatial and Temporal Distribution of Nitrate Pollution in Groundwater of Abuja, Nigeria

Abstract

Groundwater has been recognized as playing a very important role in the development of Abuja, Nigeria's Capital as many households, private and government establishments depends solely on hand-dug wells and boreholes for their daily water needs. Exploitation of groundwater is rather delicate because of its potency to contamination and difficulty to remediate when compared to surface water. The purpose of this paper is to present the occurrence of nitrate in groundwater of Abuja and discuss the implication and sources of the nitrate. High nitrate level in drinking water leads to infant methaemoglobinaemia (blue-baby syndrome), gastric cancer, metabolic disorder and livestock poisoning. A simplified map of nitrate occurrences in Abuja indicates that some areas have nitrate concentration above the WHO and NSDWQ guide limit of 50 mg/l and it is dominant in the rainy season than dry season. The number of people drinking water with nitrate concentration above the permissible level cannot be quantified presently. The sources of nitrate in the groundwater were attributed to bedrock dissolution in the course of groundwater migration and more importantly anthropogenic activities such as on-site sanitation, waste dumpsites and agricultural chemicals. Water treatment by bio-denitrification and nitrate pollution control programs should be introduced at local, state and federal levels in order to educate people on the need to protect groundwater from nitrate pollution caused by agricultural activity and indiscriminate disposal of wastes.Keywords: anthropogenic activity, nitrate pollution, groundwater, Abuja IntroductionThe problem of nitrate pollution in groundwater is a common global phenomenon and has been reported by various authors in many parts of Nigeria (Egboka & Ezeonu, 1990;Uma, 1993;Edet, 2000;Adelana & Olasehinde, 2003;Amadi, 2010). The presence of nitrate in groundwater can be derived from natural and/or anthropogenic sources. The soil/rock-water interactions can result to weathering and enrichment of the groundwater with ammonium ions, since groundwater quality is a function of the chemical composition of the soil/rock through which it passes (Amadi, 2010). The chemistry of groundwater is generally conditioned by the nature of the rock formation through which it flows. The sources and distribution of nitrate in groundwater have been studied in some details in Botswana (Staudt, 2003;Vogel et al., 2004;Schiwiede et al., 2005;Stadler, 2005), Namibia (Heaton, 1984;Wrabel, 2005) and South Africa (Tredoux, 2004;Tredoux et al., 2005). These studies have shown that pollution by anthropogenic activities is the main source of high and variable levels in groundwater. Such activities includes inappropriate on-site sanitation and wastewater treatment, improper sewage sludge drying and disposal, livestock concentration at watering points near boreholes and farming activities by application of nitrogenous fertilizers.

Assessment of irrigation water qualities of Abak River, Abak, Akwa Ibom State, Nigeria

“…Fresh water is most essential among water resources, it is essential for human being's life and activities. The availability of clean fresh water is one of the greatest challenges facing mankind today as millions of people especially in rural areas still lack access to potable water (Dan Hassan et. al., 2012 andAmadi et.…”

Lithologic Influence on the Hydrogeochemical Characteristics of Groundwater in Zango, North-west Nigeria

“…These values fall significantly below the permissible limit of 250.0 mg/l [17,12]. High chloride content in groundwater may indicate pollution by sewage, effluent or marine source [2,9]. Although the chloride concentrations in the area are within the recommended value, the highest values fall within the granite and rhyolite region, an indication of geogenic source.…”

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

“…Consequently, this could introduce nitrates into groundwater reserve in the area. Thus, they are a number of studies that have shown the impact of waste as a contributing factor to the presence of nitrates in groundwater [9,15].…”

“…Which can be achieved conveniently with the provision of these spatial maps. Consequently, there is a growing number of literature on the spatial variation of Nitrates [6,7,8,9]. However, not much has been done to map out the spatial distribution of Nitrate levels in the groundwater of the study area.…”