In this study, metal pollution index (MPI) and principal component analysis (PCA) techniques were applied to water quality data sets obtained from River Chanchaga, Minna, North-central Nigeria, to obtain the spatial and temporal changes in the river quality. Results show that the indices which changed the quality of the river water consist of natural (weathering and bedrock dissolution) and anthropogenic activities such as mining, agriculture, domestic and industrial wastes within its catchment. The result of the MPI indicates that the river is slightly affected with respect to heavy metal pollution, which can be attributed the gold mineralization and mining along the river course. Five principal factors were generated when the data was subjected to PCA and they correspond to five possible point source of pollution to the river. Factors 1 and 2 are naturally induced while factors 3, 4 and 5 are due to anthropogenic interference in the hydrological cycle. Although, the river quality does not pose any serious threat to human health presently, the various anthropogenic activities domiciled at the downstream should discontinue, in order restore the river water quality. The people living close to the river should adopt a good sanitary habit by not dumping waste into the river henceforth. Boiling of the water before consumption is advocated.

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.

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Groundwater pollution is one of the environmental problems facing many coastal regions such as Niger Delta as a result of high population, urbanization and industrialization. The quality of groundwater in the Eastern Niger-Delta, Nigeria was investigated in this study using multivariate geostatistical techniques. Hydrogeological investigations show that the aquifers in the area are largely unconfined sands with intercalations of gravels, clay and shale. These findings indicate that the aquifer in the area is porous, permeable and prolific. The observed wide ranges and high standard deviations and mean in the geochemical data are evidence that there are substantial differences in the quality/composition of the groundwater within the study area. Heavy metal enrichment index revealed 12 elements in the decreasing order of: Fe > Ni > Cu > Zn > Mn > Cd > V > Co > Pb > Cr > As > Hg. The study identified salt intrusion, high iron content, acid-rain, hydrocarbon pollution, use of agrochemicals, industrial effluents and poor sanitation as contributors to the soil and water deterioration in the area. Saltwater/freshwater interface occurs between 5 m to 185 m while iron-rich water is found between 20 m to 175 m. The first two factors are natural phenomenon due to the proximity of the aquifer to the ocean and probably downward leaching of marcasite contained in the overlying lithology into the shallow water table while the last four factors are results of various anthropogenic activities domiciled in the area. Owing to the monumental and devastating effects of hydrocarbon pollution in the area, the need to eradicate gas flaring and minimize oil spills in the area was advocated. The geostatistical evaluation approach employed in this study gave rise to the development of groundwater vulnerability map of Eastern Niger Delta. Communities where their boreholes have been contaminated by hydrocarbon should stop using such wells and government should provide them with alternative source of water for drinking and domestic purposes.

The effects of leachate from unlined open waste dumps on the soil and aquifer system in Avu and Ihie area of Southeastern Nigeria was investigated in this study. The soil pH in both dumpsites is very low and it is a reflection of the microbial action in the process of decomposition of waste materials as well as the acid-rain formation via gas flaring. It was established that the mean concentrations of manganese, lead, iron and bacteria count were higher in Avu dumpsite soil while the other parameters are higher at Ihie dumpsite soil. The concentrations of all the parameters analyzed were below the crustal abundance of the respective elements except cadmium. The high concentration of cadmium can be attributed to the decay of abandoned electric batteries and other electrical parts. The soil samples collected far away from the dumpsites have lower concentrations compared to the samples collected in the vicinity of the dumpsites suggesting a possible soil contamination via leachate from the nearby dumpsites. The graphs of sieve and correlation analyses from the dumpsites were very similar and this implies similarity in wastes materials and geohistory. Construction of future dumpsites in the area should follow the prescribed design of a modern sanitary landfill system that quarantee protection to the soil and aquifer materials.